A valid food frequency questionnaire for measuring dietary fish intake

Higher plant-derived nitrate intake is associated with lower odds of frailty in a cross-sectional study of community-dwelling older women

PURPOSE

Dietary nitrate intake is inversely related to numerous contributors towards frailty, including cardiovascular disease and poor physical function. Whether these findings extend to frailty remain unknown. We investigated if habitual nitrate intake, derived from plants or animal-based foods, was cross-sectionally associated with frailty in women.

METHODS

Community-dwelling older Australian women (n = 1390, mean age 75.1 ± 2.7 years) completed a validated semi-quantitative food frequency questionnaire (FFQ). Nitrate concentrations in food were obtained from international nitrate databases. We adopted the Rockwood frailty index (FI) of cumulative deficits comprising 33 variables across multiple health domains (scored 0 to 1), which predicts increased hospitalisation and mortality risk. A FI ≥ 0.25 indicated frailty. Cross-sectional associations between nitrate intake (total plant and animal nitrate, separately) and frailty were analysed using multivariable-adjusted logistic regression models (including lifestyle factors), as part of restricted cubic splines.

RESULTS

A non-linear inverse relationship was observed between total plant nitrate intake and frailty. Compared to women with the lowest plant nitrate intake (Quartile [Q]1), women with greater intakes in Q2 (OR 0.69 95%CI 0.56-0.84), Q3 (OR 0.67 95%CI 0.50-0.90) and Q4 (OR 0.66 95%CI 0.45-0.98) had lower odds for frailty. A nadir in the inverse association was observed once intakes reached ~ 64 mg/d (median Q2). No relationship was observed between total animal nitrate and frailty.

CONCLUSION

Community-dwelling older women consuming low amounts of plant-derived nitrate were more likely to present with frailty. Consuming at least one daily serving (~ 75 g) of nitrate-rich green leafy vegetables may be beneficial in preventing frailty.

Associations Between Fruit Intake and Risk of Diabetes in the AusDiab Cohort

CONTEXT

Fruit, but not fruit juice, intake is inversely associated with type 2 diabetes mellitus (T2DM). However, questions remain about the mechanisms by which fruits may confer protection.

OBJECTIVE

The aims of this work were to examine associations between intake of fruit types and 1) measures of glucose tolerance and insulin sensitivity and 2) diabetes at follow-up.

METHODS

Among participants of the Australian Diabetes, Obesity and Lifestyle Study, fruit and fruit juice intake was assessed by food frequency questionnaire at baseline. Associations between fruit and fruit juice intake and 1) fasting plasma glucose, 2-hour postload plasma glucose, updated homeostasis model assessment of insulin resistance of β-cell function (HOMA2-%β), HOMA2 of insulin sensitivity (HOMA2-%S), and fasting insulin levels at baseline and 2) the presence of diabetes at follow-up (5 and 12 years) were assessed using restricted cubic splines in logistic and linear regression models.

RESULTS

This population of 7675 Australians (45% males) had a mean ± SD age of 54 ± 12 years at baseline. Total fruit intake was inversely associated with serum insulin and HOMA2-%β, and positively associated with HOMA2-%S at baseline. Compared to participants with the lowest intakes (quartile 1), participants with moderate total fruit intakes (quartile 3) had 36% lower odds of having diabetes at 5 years (odds ratio, 0.64; 95% CI, 0.44-0.92), after adjusting for dietary and lifestyle confounders. Associations with 12-year outcomes were not statistically significant.

CONCLUSION

A healthy diet including whole fruits, but not fruit juice, may play a role in mitigating T2DM risk.

Dietary Nitrate Intake Is Positively Associated with Muscle Function in Men and Women Independent of Physical Activity Levels

BACKGROUND

Nitrate supplements can improve vascular and muscle function. Whether higher habitual dietary nitrate is associated with better muscle function remains underexplored.

OBJECTIVE

The aim was to examine whether habitual dietary nitrate intake is associated with better muscle function in a prospective cohort of men and women, and whether the relation was dependent on levels of physical activity.

METHODS

The sample (n = 3759) was drawn from the Australian Diabetes, Obesity, and Lifestyle Study (AusDiab) (56% female; mean ± SD baseline age: 48.6 ± 11.1 y). Habitual dietary intake was assessed over 12 y by obtaining an average [of at least 2 time points, e.g., baseline (2000/2001) and 2004/2005 and/or 2011/2012] from a food-frequency questionnaire. Nitrate intake was calculated from a validated nitrate database and other published literature. Muscle function was quantified by knee extension strength (KES) and the 8-ft-timed-up-and-go (8ft-TUG) test performed in 2011/2012. Physical activity was assessed by questionnaire. Generalized linear models and logistic regression were used to analyze the data.

RESULTS

Median (IQR) total nitrate intake was 65 (52-83) mg/d, with ∼81% derived from vegetables. Individuals in the highest tertile of nitrate intake (median intake: 91 mg/d) had 2.6 kg stronger KES (11%) and 0.24 s faster 8ft-TUG (4%) compared with individuals in the lowest tertile of nitrate intake (median intake: 47 mg/d; both P < 0.05). Similarly, individuals in the highest tertile of nitrate intake had lower odds for weak KES (adjusted OR: 0.69; 95% CI: 0.47, 0.73) and slow 8ft-TUG (adjusted OR: 0.63; 95% CI: 0.50, 0.78) compared with those in the lowest tertile. Physical activity did not influence the relationship between nitrate intake and muscle function (KES; P-interaction = 0.86; 8ft-TUG; P-interaction = 0.99).

CONCLUSIONS

Higher habitual dietary nitrate intake, predominantly from vegetables, could be an effective way to promote lower-limb muscle strength and physical function in men and women.

Cruciferous vegetable intake is inversely associated with extensive abdominal aortic calcification in elderly women: a cross-sectional study

We have previously shown that higher intake of cruciferous vegetables is inversely associated with carotid artery intima-media thickness. To further test the hypothesis that an increased consumption of cruciferous vegetables is associated with reduced indicators of structural vascular disease in other areas of the vascular tree, we aimed to investigate the cross-sectional association between cruciferous vegetable intake and extensive calcification in the abdominal aorta. Dietary intake was assessed, using a FFQ, in 684 older women from the Calcium Intake Fracture Outcome Study. Cruciferous vegetables included cabbage, Brussels sprouts, cauliflower and broccoli. Abdominal aortic calcification (AAC) was scored using the Kauppila AAC24 scale on dual-energy X-ray absorptiometry lateral spine images and was categorised as ‘not extensive’ (0–5) or ‘extensive’ (≥6). Mean age was 74·9 (sd 2·6) years, median cruciferous vegetable intake was 28·2 (interquartile range 15·0–44·7) g/d and 128/684 (18·7 %) women had extensive AAC scores. Those with higher intakes of cruciferous vegetables (>44·6 g/d) were associated with a 46 % lower odds of having extensive AAC in comparison with those with lower intakes (<15·0 g/d) after adjustment for lifestyle, dietary and CVD risk factors (OR_{Q4 v. Q1} 0·54, 95 % CI 0·30, 0·97, P = 0·036). Total vegetable intake and each of the other vegetable types were not related to extensive AAC (P > 0·05 for all). This study strengthens the hypothesis that higher intake of cruciferous vegetables may protect against vascular calcification.

Dietary nitrate intake is associated with muscle function in older women

BACKGROUND

In younger individuals, dietary nitrate supplementation has been shown to improve short-term vascular and muscle function. The role of higher habitual nitrate intake as part of a typical diet on muscle function in ageing has not been investigated. A cross-sectional study of relationships between dietary nitrate and measures of muscle function in older community-dwelling Australian women (n = 1420, ≥70 years) was undertaken.

METHODS

Participants completed a semi-quantitative food frequency questionnaire assessing dietary intake over the previous year. Total nitrate from vegetables and non-vegetable sources was calculated from a validated instrument that quantified the nitrate content of food recorded within the food frequency questionnaire. Handgrip strength and timed-up-and-go (TUG) were assessed, representing muscle strength and physical function, respectively. Cut-points for weak grip strength (<22 kg) and slow TUG (>10.2 s) were selected due to their association with adverse outcomes. Linear and logistic regressions were used to examine the relationship between total nitrate intake and muscle function measures.

RESULTS

Mean ± standard deviation (SD) total nitrate intake was 79.5 ± 31.2 mg/day, of which 84.5% came from vegetables. Across the unadjusted tertiles of nitrate intake (<64.2 mg/day; 64.2 to <89.0 mg/day; ≥89.0 mg/day), women in the highest tertile had a 4% stronger grip strength and a 5% faster TUG performance compared with the lowest tertile. In multivariable-adjusted models, each SD higher nitrate intake (31.2 mg/day) was associated with stronger grip strength (per kilogram, β 0.31, P = 0.027) and faster TUG (per second, β -0.27, P = 0.001). The proportion of women with weak grip strength (<22 kg) or slow TUG (>10.2 s) was 61.0% and 36.9%, respectively. Each SD higher nitrate intake (31.2 mg/day) was associated with lower odds for weak grip strength (OR 0.84, 95% CI 0.74-0.95, P = 0.005) and slow TUG (OR 0.86, 95% CI 0.76-0.98, P = 0.021). Compared with women in the lowest tertile of nitrate intake, women in the highest nitrate intake tertile had lower odds for weak grip strength (OR 0.65, 95% CI 0.49-0.87, P_trend= 0.004) and slow TUG (OR 0.72, 95% CI 0.53-0.97, P_trend  = 0.044).

CONCLUSIONS

This investigation highlights potential benefits of nitrate-rich diets on muscle strength and physical function in a large cohort of older women. Considering poor muscle strength and physical function is associated with a range of adverse health outcomes such as falling, fractures, cardiovascular disease, and mortality, increasing dietary nitrate, especially though vegetable consumption may be an effective way to limit age-related declines in muscle function.

Vegetable and fruit intake and injurious falls risk in older women: a prospective cohort study

The role of vegetable and fruit intake in reducing falls risk in elderly populations is uncertain. This study examined the associations of vegetable and fruit intake with falls-related hospitalisations in a prospective cohort study of elderly women (n 1429, ≥70 years), including effects on muscular function, which represented a potential causal pathway. Muscular function, measured using grip strength and timed-up-and-go (TUG), and vegetable and fruit intake, quantified using a validated FFQ, were assessed at baseline (1998). Incident falls-related hospitalisation over 14·5-year follow-up was captured by the Hospital Morbidity Data Collection, linked via the Western Australian Data Linkage System. Falls-related hospitalisation occurred in 568 (39·7 %) of women. In multivariable-adjusted models, falls-related hospitalisations were lower in participants consuming more vegetables (hazard ratio (HR) per 75 g serve: 0·90 (95 % CI 0·82, 0·99)), but not fruit intake (per 150 g serve: 1·03 (95 % CI 0·93, 1·14)). Only total cruciferous vegetable intake was inversely associated with falls-related hospitalisation (HR: per 20 g serve: 0·90 (95 % CI 0·83, 0·97)). Higher total vegetable intake was associated with lower odds for poor grip strength (OR: 0·87 (95 % CI 0·77, 0·97)) and slow TUG (OR: 0·88 (95 % CI 0·78, 0·99)). Including grip strength and TUG in the multivariable-adjusted model attenuated the association between total vegetable intake and falls-related hospitalisations. In conclusion, elderly women with higher total and cruciferous vegetable intake had lower injurious falls risk, which may be explained in a large part by better physical function. Falls reduction may be considered an additional benefit of higher vegetable intake in older women.

Cruciferous and Total Vegetable Intakes Are Inversely Associated With Subclinical Atherosclerosis in Older Adult Women

Background

Dietary patterns rich in fruits and vegetables are considered to reduce atherosclerotic disease presentation and are reported to be inversely associated with subclinical measures of atherosclerosis, such as carotid artery intima‐media thickness (IMT) and plaque. However, the effect of vegetable intake alone, and relationships to specific types of vegetables containing different phytochemical profiles, is important. The aim of this study was to investigate the associations of total vegetable intake and specific vegetables grouped according to phytochemical constituents with common carotid artery IMT (CCA‐IMT) and carotid plaque severity in a cohort of older adult women (aged ≥70 years).

Methods and Results

Total vegetable intake was calculated at baseline (1998) using a validated food frequency questionnaire. Vegetable types included cruciferous, allium, yellow/orange/red, leafy green, and legumes. In 2001, CCA‐IMT (n=954) and carotid focal plaque (n=968) were assessed using high‐resolution B‐mode carotid ultrasonography. Mean (SD) total vegetable intake was 199.9 (78.0) g/d. Women consuming ≥3 servings of vegetables each day had ≈4.6% to 5.0% lower mean CCA‐IMT (P=0.014) and maximum CCA‐IMT (P=0.004) compared with participants consuming <2 servings of vegetables. For each 10 g/d higher in cruciferous vegetable intake, there was an associated 0.006 mm (0.8%) lower mean CCA‐IMT (P<0.01) and 0.007 mm (0.8%) lower maximum CCA‐IMT (P<0.01). Other vegetable types were not associated with CCA‐IMT (P>0.05). No associations were observed between vegetables and plaque severity (P>0.05).

Conclusions

Increasing vegetables in the diet with a focus on consuming cruciferous vegetables may have benefits for the prevention of subclinical atherosclerosis in older adult women.

Clinical Trial Registration

URL: http://www.anzctr.org.au. Unique identifier: ACTRN12615000750583.

Association of dietary nitrate with atherosclerotic vascular disease mortality: a prospective cohort study of older adult women

Background: Nitrate-rich vegetables lower blood pressure and improve endothelial function in humans. It is not known, however, whether increased consumption of nitrate-rich vegetables translates to a lower risk of atherosclerotic vascular disease (ASVD) mortality.Objective: The objective was to investigate the association of nitrate intake from vegetables with ASVD mortality.Design: A total of 1226 Australian women aged 70-85 y without prevalent ASVD and/or diabetes were recruited in 1998 and were studied for 15 y. We assessed demographic and ASVD risk factors at baseline (1998), and we used a validated food-frequency questionnaire to evaluate dietary intake. Nitrate intake from vegetables was calculated by use of a newly developed comprehensive database. The primary outcome was any death attributed to ASVD ascertained by using linked data that were provided via the Western Australian Data Linkage system. We used Cox proportional hazards modeling to examine the association between nitrate intake and ASVD mortality before and after adjustment for lifestyle and cardiovascular disease risk factors.Results: During a follow-up period of 15,947 person-years, 238 of 1226 (19.4%) women died of ASVD-related causes. The mean ± SD vegetable nitrate intake was 67.0 ± 29.2 mg/d. Each SD higher vegetable nitrate intake was associated with a lower risk of ASVD mortality in both unadjusted [HR: 0.80 (95% CI: 0.70, 0.92), P = 0.002] and multivariable-adjusted [HR: 0.79 (95% CI: 0.68, 0.93), P = 0.004] analyses. This relation was attenuated after further adjustment for diet quality [HR: 0.85 (95% CI: 0.72, 1.01), P = 0.072]. Higher vegetable nitrate intake (per SD) also was associated with a lower risk of all-cause mortality [multivariable-adjusted HR: 0.87 (95% CI: 0.78, 0.97), P = 0.011].Conclusions: Nitrate intake from vegetables was inversely associated with ASVD mortality independent of lifestyle and cardiovascular disease risk factors in this population of older adult women without prevalent ASVD or diabetes. These results support the concept that nitrate-rich vegetables may reduce the risk of age-related ASVD mortality. This trial was registered at www.anzctr.org.au as ACTRN12617000640303.

Vegetable and Fruit Intake and Fracture-Related Hospitalisations: A Prospective Study of Older Women

The importance of vegetable and fruit intakes for the prevention of fracture in older women is not well understood. Few studies have explored vegetable and fruit intakes separately, or the associations of specific types of vegetables and fruits with fracture hospitalisations. The objective of this study was to examine the associations of vegetable and fruit intakes, separately, and specific types of vegetables and fruits with fracture-related hospitalisations in a prospective cohort of women aged ≥70 years. Vegetable and fruit intakes were assessed at baseline (1998) in 1468 women using a food frequency questionnaire. The incidence of fracture-related hospitalisations over 14.5 years of follow-up was determined using the Hospital Morbidity Data Collection, linked via the Western Australian Data Linkage System. Fractures were identified in 415 (28.3%) women, of which 158 (10.8%) were hip fractures. Higher intakes of vegetables, but not fruits, were associated with lower fracture incidence. In multivariable-adjusted models for vegetable types, cruciferous and allium vegetables were inversely associated with all fractures, with a hazard ratio (HR) (95% confidence interval) of 0.72 (0.54, 0.95) and 0.66 (0.49, 0.88), respectively, for the highest vs. lowest quartiles. Increasing vegetable intake, with an emphasis on cruciferous and allium vegetables, may prevent fractures in older postmenopausal women.

Lower omega-3 fatty acid intake and status are associated with poorer cognitive function in older age: A comparison of individuals with and without cognitive impairment and Alzheimer's disease

OBJECTIVES

Various strands of evidence suggest that low intake of omega-3 fatty acids increases risk of cognitive decline and dementia. The present study investigated differences in dietary intake and blood plasma content of eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3) in individuals with cognitive impairment no dementia (CIND), individuals with Alzheimer's disease (AD), and healthy volunteers (HV).

METHODS

A total of 135 individuals aged between 55 and 91 years (19 AD, 55 CIND, and 61 HV) were assessed predominantly within a hospital setting.

RESULTS

Compared with age and sex-matched HV, individuals with AD or CIND performed poorly on a majority of tests of cognitive function. Impairment was greatest for delayed and verbal recognition memory. CIND individuals were less impaired than AD individuals. Omega-3 intake and the percentage of EPA and DHA in plasma phosphatidylcholine (PC) showed a similar pattern (AD < HV, with intermediate scores for CIND). Across the whole sample, and after controlling for age, years of education, level of socio-economic deprivation, and gender, omega-3 intake, plasma PC DHA, and plasma PC EPA were all significant positive predictors of memory functioning.

DISCUSSION

These results are consistent with the possibility that omega-3 fatty acid nutrition has an impact on cognitive decline, but could equally be explained by dietary changes that occurred after onset of cognitive decline. It is also possible that the results could be explained by unknown confounding factors.

Coleus forskohlii Extract Supplementation in Conjunction with a Hypocaloric Diet Reduces the Risk Factors of Metabolic Syndrome in Overweight and Obese Subjects: A Randomized Controlled Trial

Limited studies have shown that Coleus forskohlii extract may aid in weight management. This randomized, double blind placebo-controlled clinical study assessed the effects of supplementation with C. forskohlii extract on key markers of obesity and metabolic parameters in overweight and obese individuals. Thirty participants completed the trial and they were randomly assigned to receive either 250 mg of C. forskohlii extract (n = 15) or a placebo twice daily for 12 weeks. All participants were advised to follow a hypocaloric diet throughout the study. Body weight, body mass index (BMI), waist and hip circumference, and waist to hip ratio, were monitored fortnightly. Dietary intake was assessed at the baseline and weeks 4, 8 and 12. Appetite was assessed using visual analogue scales and blood samples were analyzed for plasma lipids, ghrelin, leptin, glucose and insulin at the baseline and end of the intervention. Significant reductions to waist and hip circumference (p = 0.02; p = 0.01, respectively) were recorded in both experimental and placebo groups after the 12 week intervention. Furthermore, high density lipoprotein-cholesterol (HDL-C) was significantly increased (p = 0.01) in both groups. The experimental group showed a favorable improvement in insulin concentration and insulin resistance (p = 0.001; 0.01 respectively) compared to the placebo group. These findings suggest that C. forskohlii extract in conjunction with a hypocaloric diet may be useful in the management of metabolic risk factors.

Higher intake of omega-3 polyunsaturated fatty acids is associated with a decreased risk of a first clinical diagnosis of central nervous system demyelination: Results from the Ausimmune Study

BACKGROUND

There is contradictory evidence for a role of dietary fat in risk of multiple sclerosis (MS).

OBJECTIVES

To examine the association between usual fat intake (total, saturated, monounsaturated (MUFA), polyunsaturated (PUFA), omega-3 and omega-6) and risk of a first clinical diagnosis of CNS demyelination (FCD).

METHODS

Multi-centre incident case-control study in four regions of Australia during 2003-2006. Cases were aged 18-59 years and had a FCD; controls were matched to a case on age, sex and location. Dietary data were collected using a validated food frequency questionnaire.

RESULTS

In 267 cases and 517 controls with dietary data, higher intake (per g/day) of omega-3 PUFA (adjusted odds ratio, AOR=0.61 (95% CI 0.40-0.93)), and particularly that derived from fish (AOR=0.54 (95% CI 0.31-0.93)) rather than from plants (AOR=0.75 (95% CI 0.39-1.43)) was associated with a decreased risk of FCD. Total fat intake and intake of other types of fat were not associated with FCD risk.

CONCLUSIONS

There was a significant decrease in FCD risk with higher intake of omega-3 PUFA, particularly that originating from fish. There was no evidence to indicate that the intake of other types of dietary fat or fat quantity in the previous 12 months was associated with an altered risk of FCD.

Polyunsaturated fatty acid intake and risk of cardiovascular mortality in a low fish-consuming population: a prospective cohort analysis

PURPOSE

The aim of this study was to examine the relationship between polyunsaturated fatty acids (PUFA) intake (n-6 and n-3) and mortality in a population-based sample with a low fish intake.

METHODS

Cox regression was used to examine the relationships between dietary PUFA intake and all-cause or CVD mortality in the Australian Diabetes, Obesity and Lifestyle Study (AusDiab) cohort, a population of 11,247 Australians aged ≥25 years recruited in 1999/2000 and followed until 2012. Demographic, lifestyle and behavioural information were collected by questionnaire and fasting blood tests undertaken. Dietary intake was collected by a 121-item food frequency questionnaire. Vital status and causes of death were collected by death registry linkage.

RESULTS

Those in the highest quintile of n-6 PUFA intake had lower risk of CVD mortality (HR 0.57, 95 % CI 0.38-0.86) after age and sex adjustment, but this failed to retain significance after further risk factor adjustment. Consumption of ≥1 serves/week of non-fried fish was associated with reduced risk of CVD mortality (HR 0.64, 95 % CI 0.45-0.91, p = 0.013) compared to those eating less than 1 serve/month, after sex and age adjustment, but did not retain significance after further adjustment. However, long-chain n-3 intake was not associated with CVD mortality, and those in the highest quintile of n-3 intake had a higher risk of all-cause mortality.

CONCLUSIONS

These findings do not support previous suggestions that n-6 PUFA have adverse effects on CVD risk. Greater intake of non-fried fish was associated with lower risk of CVD mortality, but those with the highest total n-3 intake were at slightly increased risk of all-cause mortality.

Comparison of single questions and brief questionnaire with longer validated food frequency questionnaire to assess adequate fruit and vegetable intake

OBJECTIVE

The aim of this study was to determine if a single question (SQ) for fruit and a SQ or five-item questionnaire for vegetable consumption (VFQ) could replace a longer food frequency questionnaire (FFQ) to screen for inadequate versus adequate intakes in populations.

METHODS

Participants (109) completed three test screeners: fruit SQ, vegetable SQ, and a five-item VFQ followed by the reference 74-item FFQ (version 2 of the Dietary Questionnaire for Epidemiological Studies [DQESv2]) including 13 fruit and 25 vegetable items. The five-item VFQ asked about intake of salad vegetables, cooked vegetables, white potatoes, legumes, and vegetable juice. The screeners were compared with the reference (DQESv2 FFQ) for sensitivity, specificity, and positive and negative predictive powers (PPV, NPV) to detect intakes of two or more servings of fruit and three or more servings of vegetables. Relative validity was examined using Bland-Altman statistics.

RESULTS

The fruit SQ showed a PPV of 56% and an NPV of 83%. The PPV for the vegetable SQ was 30% and the NPV was 89%. For the five-item VFQ, the PPV was 39% and the NPV was 85%. Bland-Altman plots and linear regression equations showed that although the screener showed good agreement for fruit (unstandardized b1 coefficient = 0.04) for vegetable intake the difference between methods increased at higher intake levels (unstandardized b1 coefficients = -0.3 for the SQ, b1 = -0.6 for five-item VFQ).

CONCLUSION

The fruit SQ and the five-item VFQ are suitable replacements for longer FFQs to detect inadequate intake and assess population mean but not individual intakes.

Steps toward improving diet and exercise for cancer survivors (STRIDE): a quasi-randomised controlled trial protocol

Background

Cancer survivorship rates have increased in developed countries largely due to population ageing and improvements in cancer care. Survivorship is a neglected phase of cancer treatment and is often associated with adverse physical and psychological effects. There is a need for broadly accessible, non-pharmacological measures that may prolong disease-free survival, reduce or alleviate co-morbidities and enhance quality of life. The aim of the Steps TowaRd Improving Diet and Exercise (STRIDE) study is to evaluate the effectiveness of an online-delivered physical activity intervention for increasing walking in cancer survivors living in metropolitan and rural areas of South Australia.

Methods/Design

This is a quasi-randomised controlled trial. The intervention period is 12-weeks with 3-month follow-up. The trial will be conducted at a university setting and community health services in South Australia. Participants will be insufficiently active and aged 18 years or older. Participants will be randomly assigned to either the intervention or control group. All participants will receive a pedometer but only the intervention group will have access to the STRIDE website where they will report steps, affect and ratings of perceived exertion (RPE) during exercise daily. Researchers will use these variables to individualise weekly step goals to increase walking.

The primary outcome measure is steps per day. The secondary outcomes are a) health measures (anthropometric and physiological), b) dietary habits (consumption of core foods and non-core foods) and c) quality of life (QOL) including physical, psychological and social wellbeing. Measures will be collected at baseline, post-intervention and 3-month follow-up.

Discussion

This protocol describes the implementation of a trial using an online resource to assist cancer survivors to become more physically active. It is an innovative tool that uses ratings of perceived exertion and daily affect to create individualised step goals for cancer survivors. The research findings may be of relevance to public health policy makers as an efficacious and inexpensive online-delivered intervention can have widespread application and may improve physical and psychological outcomes among this vulnerable population. Findings may indicate directions for the implementation of future physical activity interventions with this population.

Trial registration

Australian New Zealand Clinical Trials Registry: ACTRN12613000473763.

High fish plus fish oil intake is associated with slightly reduced risk of venous thromboembolism: the Tromsø Study

Current knowledge of the effect of fish consumption on risk of venous thromboembolism (VTE) is scarce and diverging. Therefore, the purpose of the present study was to investigate the impact of fish consumption and fish oil supplements on the risk of VTE in a population-based cohort. Weekly intake of fish for dinner and intake of fish oil supplements during the previous year were registered in 23,621 persons aged 25-97 y who participated in the Tromsø Study from 1994 to 1995. Incident VTE events were registered throughout follow-up (31 December 2010). Cox-regression models were used to calculate HRs for VTE, adjusted for age, body mass index, sex, triglycerides, HDL cholesterol, physical activity, and education level. During a median of 15.8 y of follow-up there were 536 incident VTE events. High fish consumption was associated with a slightly reduced risk of VTE. Participants who ate fish ≥3 times/wk had 22% lower risk of VTE than those who consumed fish 1-1.9 times/wk (multivariable HR: 0.78; 95% CI: 0.60, 1.01; P = 0.06). The addition of fish oil supplements strengthened the inverse association with risk of VTE. Participants who consumed fish ≥3 times/wk who additionally used fish oil supplements had 48% lower risk than those who consumed fish 1-1.9 times/wk but did not use fish oil supplements (HR: 0.52; 95% CI: 0.34, 0.79; P = 0.002). In conclusion, a high weekly intake (≥3 times/wk) of fish was associated with a slightly reduced risk of VTE, and the addition of fish oil supplements strengthened the inverse effect.

Validity and reproducibility of a food frequency questionnaire as a measure of recent dietary intake in young adults

This research assessed the relative validity and reproducibility of the Dietary Questionnaire for Epidemiological Studies (DQESV2) over one month in young adults, given the lack of concise and convenient instruments for assessing recent dietary intake in this population. Participants were recruited from a large Australian university (N = 102; 35% male; age 18–34 years; body mass index 16–37 kg/m²). Five one-day weighed food records (WFR) were administered over one month followed by the DQESV2. Estimates for nutrients (energy, protein, total fat, saturated fat, carbohydrate, sugars, dietary fibre, and alcohol) and fruit and vegetable servings were compared between methods using correlation coefficients, 95% limits of agreement, and quintile classifications. One week later, a second DQESV2 was completed by n = 77 of the participants to assess reproducibility using intra-class correlations (ICC) and weighted kappa. Comparing methods, all nutrients and fruit and vegetable servings showed significant positive correlations (P<0.05) except protein intake in males; over 60% of participants were within one quintile classification except total fat and dietary fibre intakes in males (55% and 56%, respectively); and differences in nutrient and food intakes between methods were all within +/−20% of the mean WFR values except alcohol intake in females. Between first and second administrations of the DQESV2 all ICC coefficients were positive (P<0.01) and weighted kappa coefficients ranged from 0.54 for fruit servings (including fruit juice) in males to 0.91 for protein intake in females. Over a one month period, the DQESV2 demonstrated good reproducibility for the studied nutrients and for fruit and vegetable servings and provided a valid measure of the studied nutrients, except alcohol in females, and of fruit servings (including fruit juice) in both genders, at the group level in this young adult population.

Omega-3 Polyunsaturated Fatty Acid Supplementation: Mechanism and Current Evidence in Atrial Fibrillation

Atrial fibrillation (AF) is the most prevalent arrhythmia and is associated with considerable morbidity and mortality. Available pharmacologic antiarrhythmic therapies are often ineffective in preventing the recurrence of AF, possibly because these drugs target a single pathophysiological mechanism. Given their beneficial effects on ventricular arrhythmias, omega-3 polyunsaturated fatty acids (n-3 PUFAs) have recently been investigated as possible candidates in the treatment of supraventricular arrhythmias. In this review, we explore the current understanding of the antiarrhythmic effects attributed to n-3 PUFAs including direct modulation of ionic channels, improvement of membrane fluidity, anti-inflammatory and antifibrotic effects, and modulation of sympatho-vagal balance. We will then focus on the results of epidemiologic studies exploring the associations between nutritional intake of n3 PUFAs and the incidence of AF, and will review the findings of the clinical trials investigating the effects of n-3 PUFAs supplementation in the prophylaxis of AF and in the prevention of its recurrences.

Eating the right amount of fish: inverted U-shape association between fish consumption and cognitive performance and academic achievement in Dutch adolescents

Fish consumption has shown its benefits for cognitive functioning in the elderly or children with disorders (e.g., autism, ADHD), but has rarely been investigated in relation to cognitive performance and school performance of healthy adolescents. We executed an observational study in 700 Dutch high school students aged 12-18 years. Fish consumption data, end term grades, scores on the Amsterdam Vocabulary Test, and scores on the Youth Self-Report were collected. Results revealed that 13.6% of the Dutch adolescents never ate fish, 6.4% met national guidelines, 16.9% reached half of the norm, and 63.1% did eat fish but too little to meet at least half of the norm. Analysis of variance, controlled for relevant covariates, showed significant differences between the four fish consumption groups in vocabulary (p=.05). A trend for significance was found for end term grades (p=.07). Contrast analyses demonstrated significant quadratic associations between fish consumption and vocabulary (p=.01) and end term grades (p=.01). Thus higher fish intake was associated with more advanced vocabulary and higher end term grades. However, eating more fish than the described norm seemed no longer beneficial.

A short food frequency questionnaire to assess intake of seafood and n-3 supplements: validation with biomarkers

Background

Seafood intake is associated with beneficial effects for human health. Seafood provides a number of nutrients beyond the traditionally known long chain marine n-3 fatty acids EPA, DPA and DHA, such as protein, vitamin D, iodine, selenium and vitamin B₁₂. Valid assessment of dietary seafood and n-3 supplement intakes are becoming increasingly crucial when giving recommendations to populations as seafood consumption is regarded as an important part of a healthy and balanced diet.

Methods

The aim was to validate a short FFQ developed for assessment of dietary intake of seafood and n-3 supplements using the biomarkers marine n-3 fatty acids in erythrocytes and 25(OH)D in serum.

Results

Fifty-three healthy Norwegians aged 30-64 years with a mean BMI of 25 kg/m² were compliant with the study protocol. 70% reported eating seafood for dinner one to two times per week, and 45% reported to eat seafood as spread, in salads or as snack meal three to five times or more per week. The FFQ correlated significantly with both the levels of marine n-3 fatty acids (r = 0.73, p < 0.0001) and with 25(OH)D (r = 0.37, p < 0.01). Mean level of marine n-3 and of 25(OH)D were 232 ± 65 μg/g erythrocytes and 73 ± 33 nmol/L serum, respectively.

Conclusion

The present short FFQ predicted strongly the levels of marine n-3 fatty acids in erythrocytes, and predicted fairly good the level of serum 25(OH)D and may therefore be a valid method for assessment of seafood and n-3 supplements intake among adults.

Reducing psychological distress and obesity in Australian farmers by promoting physical activity

BACKGROUND

Studies have confirmed that the rate of mental illness is no higher in rural Australians than that of urban Australians. However, the rate of poor mental health outcomes, and in particular suicide, is significantly raised in rural populations. This is thought to be due to lack of early diagnosis, health service access, the distance-decay effect, poor physical health determinants and access to firearms. Research conducted by the National Centre for Farmer Health between 2004 and 2009 reveals that there is a correlation between obesity and psychological distress among the farming community where suicide rates are recognised as high. Chronic stress overstimulates the regulation of the hypothalamic-pituitary-adrenal (HPA) axis that is associated with abdominal obesity. Increasing physical activity may block negative thoughts, increase social contact, positively influence brain chemistry and improve both physical and mental health. This paper describes the design of the Farming Fit study that aims to identify the effect of physical activity on psychological distress, obesity and health behaviours such as diet patterns and smoking in farm men and women.

METHODS/DESIGN

For this quasi-experimental (convenience sample) control-intervention study, overweight (Body Mass Index ≥25 kg/m(2)) farm men and women will be recruited from Sustainable Farm Families™ (SFF) programs held across Victoria, Australia. Baseline demographic data, health data, depression anxiety stress scale (DASS) scores, dietary information, physical activity data, anthropometric data, blood pressure and biochemical analysis of plasma and salivary cortisol levels will be collected. The intervention group will receive an exercise program and regular phone coaching in order to increase their physical activity. Analysis will evaluate the impact of the intervention by longitudinal data (baseline and post intervention) comparison of intervention and control groups.

DISCUSSION

This study is designed to examine the effect of physical activity on psychological health and other co-morbidities such as obesity, impaired glucose tolerance, hypertension and dyslipidaemia within a high-risk cohort. The outcomes of this research will be relevant to further research and service delivery programs, in particular those tailored to rural communities.

TRIAL REGISTRATION

ACTRN12610000827033.

Use of a common food frequency questionnaire (FFQ) to assess dietary patterns and their relation to allergy and asthma in Europe: pilot study of the GA2LEN FFQ

BACKGROUND/OBJECTIVES

Comparable international data on food and nutrient intake is often hindered by the lack of a common instrument to assess food intake. The objective of this study was within the Global Allergy and Asthma European Network of Excellence (GA(2)LEN), we developed and piloted a food frequency questionnaire (FFQ) to assess its validity in Europe.

SUBJECTS/METHODS

Five countries participating in GA(2)LEN took part in the pilot study. A total of 200 adults aged 31-75 years were invited to complete a FFQ in two occasions and to give a blood sample. The intra-class correlation coefficient (ICC) was used to assess repeatability of the FFQ. Plasma phospholipid fatty acids (FAs) were analysed by gas chromatography. Pearson correlation was used to analyse the correlation between estimated dietary FA intake and plasma phospholipid FA levels.

RESULTS

A total of 177 participants (89%) had complete data on FFQ(1) and plasma phospholipid FAs. In all, 152 participants (76%) completed both FFQs. ICCs between macronutrients ranged from 0.70 (saturated FAs) to 0.78 (proteins) and between 0.70 (retinol) and 0.81 (vitamin D) for micronutrients. Dietary n-3 FAs showed a good correlation with total plasma phospholipid n-3 FAs and with docosahexaenoic acid in the whole sample (0.40) and in individual countries. Poor correlations were observed for other FAs.

CONCLUSIONS

The GA(2)LEN FFQ is an appropriate tool to estimate dietary intake for a range of nutrients across Europe regardless of cultural and linguistic differences. The FFQ seems to be useful to estimate the intake of n-3 FAs but not other FAs.

Validation of a food frequency questionnaire to assess intake of n-3 polyunsaturated fatty acids in subjects with and without major depressive disorder

The role of n-3 polyunsaturated fatty acids (PUFAs) in psychiatric illness is a topic of public health importance. This report describes development and biomarker validation of a 21-item, self-report food frequency questionnaire (FFQ) intended for use in psychiatric research to assess intake of α-linolenic acid (18:3n-3 [ALA]), docosahexaenoic acid (22:6n-3 [DHA]), and eicosapentaenoic acid (20:5n-3 [EPA]). In a cross-sectional study conducted from September 2006 to September 2008, sixty-one ethnically diverse adult participants with (n=34) and without (n=27) major depressive disorder completed this n-3 PUFA FFQ and provided a plasma sample. Plasma levels of n-3 PUFAs EPA and DHA, and n-6 PUFA arachidonic acid (20:4n-6 [AA]) were quantified by gas chromatography. Using Spearman's ρ, FFQ-estimated intake correlated with plasma levels of DHA (r=0.50; P<0.0001) and EPA (r=0.38; P=0.002), but not with ALA levels (r=0.22; P=0.086). Participants were classified into quartiles by FFQ-estimated intake and plasma PUFA concentrations. Efficacy of the FFQ to rank individuals into same or adjacent plasma quartiles was 83% for DHA, 78.1% for EPA, and 70.6% for ALA; misclassification into extreme quartiles was 4.9% for DHA, 6.5% for EPA, and 8.2% for ALA. FFQ-estimated EPA intake and plasma EPA were superior to plasma AA levels as predictors of the plasma AA to EPA ratio. This brief FFQ can provide researchers and clinicians with valuable information concerning dietary intake of DHA and EPA.

Is marine mammal fat or fish intake most strongly associated with omega-3 blood levels among the Nunavik Inuit?

Here we determined the relationship between red blood cell (RBC) omega-3 (n-3) long-chain polyunsaturated fatty acids (LC-PUFAs) and usual dietary marine food product intake among 630 Nunavik Inuit adults. Marine food product intake was determined by a food frequency questionnaire (FFQ) and fatty acids were quantified in RBC membranes. Multiple linear regression was undertaken to determine the relationship between marine food product intake and RBC n-3 LC-PUFAs (dependent variable). Mean RBC n-3 LC-PUFA level was 9.16 ± 0.11% [SEM]. The highest correlations noted with RBC n-3 LC-PUFAs were for marine mammal fat (r(s)=0.41, P<0.0001) and fish (r(s)=0.35, P<0.0001). Age, total marine mammal fat and fish intakes were the variables that contributed the most to predicted RBC n-3 LC-PUFAs and explained 34%, 15% and 5%, respectively, of its variances. Our study indicates that marine mammal fat intake is more important than fish in accounting for RBC n-3 LC-PUFA levels among the Nunavik Inuit.

Exploring the mechanisms of weight loss in the SHED-IT intervention for overweight men: a mediation analysis

BACKGROUND

Statistical mediation analysis can be used to improve the design of obesity prevention and treatment programs by identifying the possible mechanisms through which an intervention achieved its effects. The aim of this study was to identify mediators of weight loss in an Internet-based weight-loss program specifically designed for overweight men.

METHODS

The Self-Help, Exercise and Diet using Information Technology (SHED-IT) program was a 3-month randomized controlled trial (Internet-based intervention group vs information only control group) that was implemented in 2007 with baseline and 6-month follow-up assessment of weight, physical activity and dietary behaviors. Intention-to-treat and per-protocol mediation analyses were conducted using a product-of-coefficients test.

RESULTS

Participants (N = 65) were overweight and obese male academic (n = 10) and non-academic (n = 27) staff and students (n = 28) from the University of Newcastle, Australia. Mean (SD) age = 35.9 (11.1) years and mean (SD) BMI = 30.6 (2.8). In the intention-to-treat analysis, both groups lost weight, but relative to the control group, the intervention did not have a statistically significant 'total effect' on weight, tau = -.507, p = .716 (95% CI = -3.277 to 2.263). In the per-protocol analysis, the intervention had a statistically significant 'total effect' on weight, tau = -4.487, p < .05 (95% CI = -8.208 to -.765). The intervention did not have a statistically significant effect on any of the hypothesized mediators and none of the behavioral variables mediated weight loss in the SHED-IT program. Although participants in the intervention group reduced their fat intake over the study period, the changes did not satisfy the criteria for mediation.

CONCLUSION

Few studies have examined the mediators of weight loss in obesity treatment interventions. While none of the hypothesized mediators satisfied the criteria for mediation in the current study, there was some evidence to suggest that overweight men in the SHED-IT intervention reduced their fat intake over the study period. Future obesity treatment and prevention programs should explore behavioral mediators of weight loss using appropriate statistical methods.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry No: ANZCTRN12607000481471.

Exploring the mechanisms of weight loss in the SHED-IT intervention for overweight men: a mediation analysis

BACKGROUND

Statistical mediation analysis can be used to improve the design of obesity prevention and treatment programs by identifying the possible mechanisms through which an intervention achieved its effects. The aim of this study was to identify mediators of weight loss in an Internet-based weight-loss program specifically designed for overweight men.

METHODS

The Self-Help, Exercise and Diet using Information Technology (SHED-IT) program was a 3-month randomized controlled trial (Internet-based intervention group vs information only control group) that was implemented in 2007 with baseline and 6-month follow-up assessment of weight, physical activity and dietary behaviors. Intention-to-treat and per-protocol mediation analyses were conducted using a product-of-coefficients test.

RESULTS

Participants (N = 65) were overweight and obese male academic (n = 10) and non-academic (n = 27) staff and students (n = 28) from the University of Newcastle, Australia. Mean (SD) age = 35.9 (11.1) years and mean (SD) BMI = 30.6 (2.8). In the intention-to-treat analysis, both groups lost weight, but relative to the control group, the intervention did not have a statistically significant 'total effect' on weight, tau = -.507, p = .716 (95% CI = -3.277 to 2.263). In the per-protocol analysis, the intervention had a statistically significant 'total effect' on weight, tau = -4.487, p < .05 (95% CI = -8.208 to -.765). The intervention did not have a statistically significant effect on any of the hypothesized mediators and none of the behavioral variables mediated weight loss in the SHED-IT program. Although participants in the intervention group reduced their fat intake over the study period, the changes did not satisfy the criteria for mediation.

CONCLUSION

Few studies have examined the mediators of weight loss in obesity treatment interventions. While none of the hypothesized mediators satisfied the criteria for mediation in the current study, there was some evidence to suggest that overweight men in the SHED-IT intervention reduced their fat intake over the study period. Future obesity treatment and prevention programs should explore behavioral mediators of weight loss using appropriate statistical methods.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry No: ANZCTRN12607000481471.

Validation of an FFQ for evaluation of EPA and DHA intake

Objective

To validate an FFQ for the assessment of dietary EPA and DHA against their relative concentrations in red blood cells (RBC).

Design

Cross-sectional analysis of baseline data. Intakes of marine food products and EPA and DHA were estimated by FFQ on the basis of consumption of marine food products in the last month. Fatty acid composition of RBC membranes was quantified by GC.

Setting

Saint-François d’Assise Hospital, Québec, Canada.

Subjects

A total of sixty-five middle-aged women who participated in a randomized clinical trial.

Results

Spearman’s correlation coefficient between intake of EPA, DHA and EPA + DHA and their corresponding concentration in RBC was 0·46, 0·40 and 0·42, respectively (allP< 0·05). Multiple regression analysis of EPA+DHA intake and RBC EPA + DHA concentration indicated positive and significant correlations for oily fish (β= 0·44, 95 % CI 0·16, 0·72,P= 0·0027), total fish (β= 0·42, 95 % CI 0·19, 0·64,P= 0·0005) and marine food products (β= 0·42, 95 % CI 0·20, 0·64,P= 0·0003). No other marine food products significantly predicted RBC EPA + DHA concentration.

Conclusions

Although the present validation study was undertaken among middle-aged women with low consumption of marine food products (<3 servings/week), our FFQ provided estimates of EPA and DHA intakes that correlated fairly well with their RBC concentrations. However, the absence of correlations between EPA + DHA intakes from different marine species suggests that a minimum EPA + DHA intake is necessary to observe a relationship with RBC EPA + DHA concentrations.

Age dependence of plasma phospholipid fatty acid levels: potential role of linoleic acid in the age-associated increase in docosahexaenoic acid and eicosapentaenoic acid concentrations

Limited information is available with respect to the association between age and the plasma phospholipid fatty acid profile. Therefore we investigated the association between plasma phospholipid fatty acid status and age after correction for sex, smoking, alcohol use, BMI and fish intake. Plasma phospholipid fatty acid composition was measured and information on fish intake and other potential covariates was collected in 234 participants of the Maastricht Aging Study. The participants were healthy individuals of both sexes with an age range between 36 and 88 years. Hierarchical linear regression analyses were applied to study the relationship between age and fatty acid concentrations. After correction for fish consumption and other relevant covariates, a significant positive relationship was observed between age of the subjects and their plasma phospholipid concentrations of DHA (22 : 6n-3, P = 0·006) and EPA (20 : 5n-3; P = 0·001). Age contributed 2·3 and 3·9 % to the amount of explained variance, respectively. The higher n-3 long-chain PUFA status at advanced age was confirmed by lower concentrations of their putative ‘shortage marker’ Osbond acid (ObA, 22 : 5n-6; P = 0·022 for the relationship with age after correction for covariates and fish intake, R2 0·022). Concentrations of linoleic acid (LA; 18 : 2n-6) were negatively associated with age (P < 0·001; R2 0·061). In conclusion, DHA and EPA concentrations appeared to be higher in older age groups, partly because of a higher fish intake and partly because of another age-associated mechanism, possibly involving the well-known competition with LA.

Plasman-3 fatty acids and psychological distress in aboriginal Cree Indians (Canada)

Objective

To examine the relationship between psychological distress (PD) and plasman-3 long-chain (LC) PUFA, i.e. EPA, docosapentaenoic acid (DPAn-3) and DHA.

Design

Population-based, cross-sectional Santé-Québec Health Survey (1991). Participants were categorized as high-level PD if they scored over the 80th percentile of the PD Index in the Santé-Québec Survey; non-distressed subjects were those who scored less than this cut-off. Associations between tertiles ofn-3 fatty acids (FA) and the risk of high-level PD were expressed as odds ratios, with the lowest tertile as the reference group.

Setting

Québec, Canada.

Subjects

Data were analysed from a representative sample of 852 James Bay Cree Indian adults aged 18 years and over.

Results

Proportions ofn-3 FA were statistically significantly lower in the PD than in the non-distressed group. After adjustment for confounders, EPA was the only individualn-3 FA significantly associated with the risk of high-level PD. Combinations of EPA + DHA or EPA + DPAn-3 + DHA or the sum ofn-3 were also associated with the risk of high-level PD. Compared with the lowest tertile of EPA + DHA, the OR for high-level PD was 0·89 (95 % CI 0·59, 1·36) for the second and 0·56 (95 % CI 0·32, 0·98) for the third tertile, after controlling for confounders.

Conclusions

In the present retrospective, cross-sectional study, we found that proportions ofn-3 LC PUFA in plasma phospholipids, markers ofn-3 LC PUFA consumption from fish, were inversely associated with PD.

Frequency and type of seafood consumed influence plasma (n-3) fatty acid concentrations

Few studies have adequately considered the type of seafood and background dietary factors when evaluating diet-biomarker and diet-disease associations. The objective of this paper is to evaluate the relationship between different seafood meals and long-chain (n-3) fatty acids [eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)] biomarkers in the Multi-Ethnic Study of Atherosclerosis (MESA) with white, Chinese-American, black, and Hispanic participants. Dietary intake from a FFQ and plasma phospholipid fatty acids were assessed in 900 MESA participants who were not taking fish oil supplements. When simultaneously adjusting for all seafood groups, concentrations of EPA and DHA in plasma phospholipids were positively correlated with nonfried fish consumption in all 4 ethnic groups (r = 0.24-0.46; P < 0.01) but not with nonfried shellfish, fried fish, or fish in mixed dishes. The magnitude of this correlation was attenuated by up to 67% when type of seafood was not taken into account. After further adjusting for demographic characteristics and other dietary characteristics in multivariate regression models, the association of nonfried fish consumption remained significant (P-trend < 0.001). Data were suggestive of a plateau effect at a nonfried fish intake of about twice weekly. The association of nonfried fish consumption was not modified by intake of (n-6) PUFA or alpha-linolenic acid. This study highlights the importance of cooking methods (nonfried vs. fried fish), types of seafood (fish vs. shellfish), and the overall seafood consumption when assessing health effects of long-chain (n-3) fatty acids of seafood consumption.

Soy food consumption does not lower LDL cholesterol in either equol or nonequol producers

BACKGROUND

Health claims link soy protein (SP) consumption, through plasma cholesterol reduction, to a decreased risk of heart disease. Soy isoflavones (ISOs), particularly in individuals who produce equol, might also contribute to lipid lowering and thus reduce SP requirements.

OBJECTIVE

The objective was to examine the contributions of SP, ISOs, and equol to the hypocholesterolemic effects of soy foods.

DESIGN

Nonsoy consumers (33 men, 58 women) with a plasma total cholesterol (TChol) concentration >5.5 mmol/L participated in a double-blind, placebo-controlled, crossover intervention trial. The subjects consumed 3 diets for 6 wk each in random order, which consisted of foods providing a daily dose of 1) 24 g SP and 70-80 mg ISOs (diet S); 2) 12 g SP, 12 g dairy protein (DP), and 70-80 mg ISOs (diet SD); and 3) 24 g DP without ISOs (diet D). Fasting plasma TChol, LDL cholesterol, HDL cholesterol, and triglycerides (TGs) were measured after each diet.

RESULTS

TChol was 3% lower with the S diet (-0.17 +/- 0.06 mmol/L; P < 0.05) than with the D diet, and TGs were 4% lower with both the S (-0.14 +/- 0.05 mmol/L; P < 0.05) and SD (-0.12 +/- 0.05 mmol/L; P < 0.05) diets. There were no significant effects on LDL cholesterol, HDL cholesterol, or the TChol:HDL cholesterol ratio. On the basis of urinary ISOs, 30 subjects were equol producers. Lipids were not affected significantly by equol production.

CONCLUSIONS

Regular consumption of foods providing 24 g SP/d from ISOs had no significant effect on plasma LDL cholesterol in mildly hypercholesterolemic subjects, regardless of equol-producing status.

Dietary validation of a new Australian food-frequency questionnaire that estimates long-chainn-3 polyunsaturated fatty acids

Currently, there is no FFQ designed to capture the intakes of the long-chain (LC)n-3 PUFA. The objectives of this study were to validate a new LCn-3 PUFA FFQ by comparison with 3 d weighed food records (FR) and to determine its reproducibility assessed 4 to 6 weeks apart. Healthy male and female subjects (n53) were recruited from Wollongong and the Australian Capital Territory, Australia. The FFQ and FR were analysed for LCn-3 PUFA intakes using a nutrient analysis software package and these intakes were compared using Wilcoxon signed rank tests and Spearman correlation coefficients. Bland–Altman analysis and quintile assignment assessed the agreement between the two methods and the FFQ's ability to rank individuals according to intakes, respectively. Comparison of intakes from FFQ and FR correlated significantly for total LCn-3 PUFA, EPA, docosapentaenoic acid (DPA) and DHA, 0·75, 0·64, 0·62 and 0·72, respectively (P < 0·05); hence, there is reasonable agreement between the FFQ and the FR in assessing LCn-3 PUFA intakes. Quintile assignments correctly assigned 49 % of subjects into the same quintiles and 87 % of subjects were correctly assigned either to the same or adjacent quintiles. The FFQ was reproducible for intakes of LCn-3 PUFA, EPA, DPA and DHA with Spearman correlation coefficients of 0·88, 0·88, 0·90 and 0·87, respectively. In conclusion, the new FFQ is a valid and reproducible method that can be used to estimate the LCn-3 PUFA intake of healthy adults.

Do aggregates of multiple questions better capture overall fish consumption than summary questions?

Objective

To compare intake estimates, validity and reliability of two summary questions to measure fish consumption with information from a detailed semi-quantitative food-frequency questionnaire (FFQ) on fish consumption.

Design

Population-based, cross-sectional study. Participants completed an FFQ and provided blood samples for erythrocyte membrane eicosapentaenoic acid (EPA) analysis. Aggregate measures of consumption of fresh/frozen/canned fish (fresh fish) and smoked/salted/dried fish (preserved fish) were generated from the FFQ and were compared with responses to the summary questions regarding intakes of similar items. Both methods were tested for validity, using correlation and linear regression techniques with EPA, and retest reliability.

Setting

Perth metropolitan area, Western Australia.

Subjects

One hundred and nine healthy volunteers of both sexes, aged 21–75 years.

Results

The summary fresh fish measure underestimated frequency and grams per week given by the aggregate question by about 50%, while estimates from the summary preserved fish measure were approximately three times that of the aggregate measure. Multiple linear regression analysis suggested that the aggregates accounted for more of the variation in EPA levels, but the difference was minimal. Intra-class correlations confirmed that both methods were reliable.

Conclusions

Our study indicates that extensive questioning results in different absolute intakes of fish compared with brief questioning, but does not add any information if ranking individuals according to overall consumption of fish.

Comparison between plasma and erythrocyte fatty acid content as biomarkers of fatty acid intake in US women

BACKGROUND

Erythrocyte fatty acids may be superior to plasma fatty acids for reflecting long-term fatty acid intake because of less sensitivity to recent intake and a slower turnover rate.

OBJECTIVE

The objective was to compare the fatty acid content of erythrocytes with that of plasma with respect to their abilities to reflect usual fatty acid intake.

DESIGN

Fatty acids in plasma and erythrocytes were measured by capillary gas-liquid chromatography in 306 US women aged 43-69 y. Fatty acid intake was assessed with a food-frequency questionnaire, which was validated for measuring intakes of various fatty acids.

RESULTS

Docosahexaenoic acid (DHA, 22:6n-3) in erythrocytes and plasma provided the strongest correlations with its intake, but erythrocyte DHA concentrations [Spearman's partial correlation coefficient (r(s))=0.56] were better than plasma DHA concentrations (r(s)=0.48) as a biomarker. Total trans fatty acids (r(s)=0.43) and total 18:1 trans isomers (r(s)=0.42) in erythrocytes were also more strongly correlated with intake than were those in plasma (r(s)=0.30 and r(s)=0.29, respectively). Moderate correlations were observed for linoleic acid (18:2n-6; erythrocytes, r(s)=0.24; plasma, r(s)=0.25), alpha-linolenic acid (18:3n-3; erythrocytes, r(s)=0.18; plasma, r(s)=0.23), and eicosapentaenoic acid (20:5 n-3; erythrocytes, r(s)=0.38; plasma, r(s)=0.21). For polyunsaturated and trans fatty acids, correlations between intakes and biomarkers improved moderately when average intakes over previous years were used.

CONCLUSION

Erythrocyte n-3 fatty acids of marine origin and trans fatty acid content are suitable biomarkers for long-term intake.

Plasma phospholipid fatty acid composition as a biomarker of habitual dietary fat intake in an ethnically diverse cohort

BACKGROUND AND AIM

As an evaluation of fatty acid intake measurement, our aim was to examine associations between diet and plasma phospholipid (PL) fatty acids, and whether these were modified by age, sex, country of birth, fasting status, use of cholesterol-lowering medication, body size, chronic disease and other lifestyle factors.

METHODS AND RESULTS

Cross-sectional analysis of plasma PL fatty acid composition and dietary fatty acid intake over 12 months from a 121-item food frequency questionnaire (FFQ) in 4439 men and women aged 40-69 years, born in Australia, Greece or Italy. Crude correlation coefficients ranged from 0.18 to 0.40; and corrected correlation coefficients from 0.38 to 0.78 for total monounsaturated, polyunsaturated, n-6, n-3 fatty acids, oleic acid, linoleic acid, EPA and DHA. Weaker associations were observed for other fatty acids. The associations did not vary significantly by fasting status, use of lipid lowering medication or alcohol intake, but for some fatty acids did vary by sex, age, body mass index, country of birth, smoking and previous heart attack or diabetes.

CONCLUSIONS

The FFQ provides useful information on intakes of mono- and polyunsaturated fatty acids. Correlations did not differ by fasting status, or use of lipid-lowering medication.

Validation of a FFQ to estimate the intake of PUFA using plasma phospholipid fatty acids and weighed foods records

Due to the growing knowledge about the role of specific fatty acids in health and disease, dietary intake measurements of individual fatty acids or classes of fatty acids are becoming increasingly important. The objective of this study was to evaluate the ability of the Nambour FFQ to estimate intakes of specific fatty acids, particularly PUFA. The study population was a sub-sample of adult participants in a randomised controlled trial of beta-carotene and sunscreen in the prevention of skin cancer (n 43). Dietary intake was assessed by a self-administered FFQ and a weighed food record (WFR). Non-fasting blood samples were collected and analysed for plasma phospholipid fatty acids. Median intakes on the FFQ were generally higher than the WFR except for the n-3 PUFA groups, where the FFQ estimated higher intakes. Correlations between the FFQ and WFR were moderate (r 0 x 32-0 x 59) except for trans fatty acids (r 0 x 03). Correlations between each of the dietary assessment methods and the plasma phospholipids were poor for all fatty acids other than the PUFA. Using the methods of triads approach, the FFQ validity coefficients for total n-3 fatty acids, total long chain n-3 fatty acids, EPA, arachidonic acid, docosapentaenoic acid and DHA were 0 x 50, 0 x 63, 0 x 45 and 0 x 62 and 0 x 62, respectively. For most fatty acids, the FFQ adequately estimates group mean fatty acid intakes and can adequately rank individuals; however, the ability of this FFQ to estimate trans fatty acids was poor.

A valid semiquantitative food frequency questionnaire to measure fish consumption

OBJECTIVE

To validate a detailed semiquantitative food frequency questionnaire designed to measure habitual fish and seafood consumption.

DESIGN

Cross-sectional validation study using an independent biomarker of fish consumption.

SETTING

Perth metropolitan area, Western Australia.

SUBJECTS

Ninety-one healthy volunteers of both sexes aged 21-75 years.

METHODS

Participants completed the questionnaire and provided a fasting blood sample for erythrocyte membrane omega-3 fatty acid (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)) analysis. The questionnaire was then validated by linear regression analysis of EPA and DHA levels on categories of fish and seafood and overall consumption, adjusted for age, sex, smoking status, body mass index (BMI) and alcohol intake.

RESULTS

Regression coefficients were statistically significant for most fish and seafood items with both EPA and DHA. The strongest association was observed between oily fish and EPA, whereas no significant association was observed between lean fish and omega-3 fatty acids. Variation in omega-3 fatty acids was best accounted for by a model containing variables representing different categories of fish and seafood consumption (R (2) 0.484), rather than a single variable representing overall fish and seafood consumption (R (2) 0.313).

CONCLUSIONS

This study confirms that the varying content of omega-3 fatty acids in foods are reflected in omega-3 biomarkers, and that the questionnaire is a valid measure of fish consumption that enables differentiation between cooking and processing methods and oily versus lean fish intake.

Dietary fish intake and plasma phospholipid n-3 polyunsaturated fatty acid concentrations in men and women in the European Prospective Investigation into Cancer-Norfolk United Kingdom cohort

BACKGROUND

The n-3 polyunsaturated fatty acids (n-3 PUFAs) docosahexaenoic acid and eicosapentaenoic acid, found in fish and fish-oil supplements and also formed by conversion of alpha-linolenic acid in soy and rapeseed (canola) oils, are thought to have cardioprotective effects.

OBJECTIVE

Because the relative feasibility and measurement error of dietary methods varies, this study compared fish and fish-oil intakes obtained from 4 dietary methods with plasma n-3 PUFAs in men and women in a general population.

DESIGN

The study participants were 4949 men and women aged 40-79 y from the European Prospective Investigation into Cancer-Norfolk United Kingdom cohort. Measurements of plasma phospholipid n-3 PUFA concentrations and fish intakes were made with the use of 4 dietary methods (food-frequency questionnaire, health and lifestyle questionnaire, 7-d diary, and first-day recall from the 7-d diary).

RESULTS

Amounts of fish consumed and relations with plasma phospholipid n-3 PUFAs were not substantially different between the 4 dietary methods. Plasma n-3 PUFA concentrations were significantly higher in women than in men, were 20% higher in fish-oil consumers than in non-fish-oil consumers, and were twice as high in fatty fish consumers as in total fish consumers. Only approximately 25% of the variation in plasma n-3 PUFA was explained by fish and fish-oil consumption.

CONCLUSIONS

This large study found no substantial differences between dietary methods and observed clear sex differences in plasma n-3 PUFAs. Because variation in n-3 PUFA was only partially determined by fish and fish-oil consumption, this could explain the inconsistent results of observational and intervention studies on coronary artery disease protection.

Biomarker validation of a long-chain omega-3 polyunsaturated fatty acid food frequency questionnaire

Long-chain omega-3 PUFA (LC n-3 PUFA) are beneficial for health. To date there is no specific food frequency questionnaire (FFQ) to assess LC n-3 PUFA intakes. The objective of this study is to validate our newly developed FFQ by comparison with LC n-3 PUFA content of both red blood cells (RBC) and plasma, expressed as a percentage of total FA. Fifty-three healthy male and female subjects were recruited from Wollongong, Australia. Average LC n-3 PUFA intakes (mg/d) were estimated using the new FFQ. RBC and plasma FA were assessed using GC. Spearman correlation coefficients were used to assess the linear relationship between FFQ intakes and both RBC and plasma FA. The results show that there were significant Spearman's correlation coefficients between the FFQ intakes and RBC (and plasma) FA for total LC n-3 PUFA, EPA, and DHA (0.50 (0.54), 0.39 (0.54) and 0.40 (0.48), respectively) but not for docosapentaenoic acid. The FFQ was also an effective ranking tool. The FFQ is a valid method based on erythrocyte and plasma FA as biochemical markers. In conclusion, the new FFQ is a valid method that can be used to estimate the LC n-3 PUFA intake of adults.

Intake frequency of fish and serum levels of long-chain n-3 fatty acids: a cross-sectional study within the Japan Collaborative Cohort Study

BACKGROUND: Several investigations have adopted self-reported intake frequency of fish as a surrogate for intake of long-chain n-3 fatty acids, for which protective effects against cancer have been suggested. Whether reported fish consumption reflects the fatty acid intake, however, has to be elucidated.

METHODS: We examined the association between intake frequency of fish and serum long-chain n-3 fatty acids (weight percentage of total fatty acids) among 1,257 control subjects (631 men and 626 women), aged 40-79 years, in case-control studies nested in the Japan Collaborative Cohort Study. All the subjects were not fasting when blood was drawn. Serum fatty acids were determined by gas chromatography.

RESULTS: In men, intake frequency of fresh fish and dried or salted fish was significantly but weakly correlated with serum levels of eicosapentaenoic (EPA), docosapentaenoic (n-3) (DPA), and docosahexaenoic (DHA) acids; the age-adjusted Spearman correlation coefficients ranged from 0.11 to 0.18. In women, fresh fish consumption was somewhat associated with serum EPA (Spearman correlation coefficient = 0.12) as was dried or salted fish consumption with serum DPA (0.11). A rising trend in geometric means of serum EPA, DPA, and DHA was found with an increasing intake frequency of fresh or dried/salted fish in both sexes. The geometric means adjusted for age and participating institution in the highest intake category were higher than those in the lowest by 7% to 40%.

CONCLUSIONS: A population with high self-reported frequency of fish intake, as a group, may have higher bioavailability of long-chain n-3 fatty acids than one with low frequency.

Fatty acid levels and risk of asthma in young adults

BACKGROUND

There is current interest in the possible protective effect of long chain (n-3) fatty acids from fish in chronic lung diseases such as asthma. The aim of this community based cross sectional study was to determine whether plasma long chain (n-3) fatty acids, as a measure of dietary intake, differed between 1601 young adults with and without asthma.

METHODS

Subjects of mean (SD) age 34.6 (7.1) years completed a detailed respiratory questionnaire, food frequency questionnaire, skin prick testing, and lung function tests including methacholine challenge test for bronchial hyperreactivity (BHR) and had venous blood taken for analysis of plasma fatty acids. Plasma fatty acid levels (%) were analysed using multiple logistic regression with alternative definitions of asthma and atopy as the outcomes.

RESULTS

Atopy was not associated with any plasma fatty acid. The n-3 polyunsaturated fatty acids and n-6:n-3 ratio were not consistently associated with asthma or atopy. The n-6 polyunsaturated fatty acid dihomo gamma-linolenic acid (DHGLA) was positively associated with current asthma (OR=1.30, 95% CI 1.06 to 1.60), asthma (OR=1.34, 95% CI 1.13 to 1.60), and doctor diagnosed asthma (OR=1.25, 95% CI 1.06 to 1.48).

CONCLUSION

Plasma n-3 fatty acids are not associated with a reduced risk of asthma or atopy among young adults. The association of DHGLA with asthma warrants further research to determine a cause-effect relationship.