Cardiovascular event risk in relation to dietary fat intake in middle-aged individuals: data from The Malmö Diet and Cancer Study

Dietary Macronutrient Intake and Cardiovascular Disease Risk and Mortality: A Systematic Review and Dose-Response Meta-Analysis of Prospective Cohort Studies

Many epidemiological studies have evaluated the intake of macronutrients and the risk of mortality and cardiovascular disease (CVD). However, current evidence is conflicting and warrants further investigation. Therefore, we carried out an umbrella review to examine and quantify the potential dose-response association of dietary macronutrient intake with CVD morbidity and mortality. Prospective cohort studies from PubMed, Embase, and CENTRAL were reviewed, which reported associations of macronutrients (protein, fat, and carbohydrate) with all-cause, CVD, cancer mortality, or CVD events. Multivariable relative risks (RR) were pooled, and heterogeneity was assessed. The results of 124 prospective cohort studies were included in the systematic review and 101 in the meta-analysis. During the follow-up period from 2.2 to 30 years, 506,086 deaths and 79,585 CVD events occurred among 5,107,821 participants. High total protein intake was associated with low CVD morbidity (RR 0.88, 95% confidence interval 0.82-0.94), while high total carbohydrate intake was associated with high CVD morbidity (1.08, 1.02-1.13). For fats, a high intake of total fat was associated with a decreased all-cause mortality risk (0.92, 0.85-0.99). Saturated fatty acid intake was only associated with cancer mortality (1.10, 1.06-1.14); Both monounsaturated fatty acid (MUFA) and polyunsaturated fatty acids (PUFA) intake was associated with all-cause mortality (MUFA: 0.92, 0.86-0.98; PUFA: 0.91, 0.86-0.96). This meta-analysis supports that protein intake is associated with a decreased risk of CVD morbidity, while carbohydrate intake is associated with an increased risk of CVD morbidity. High total fat intake is associated with a low risk of all-cause mortality, and this effect was different in an analysis stratified by the type of fat.

Vegetable Oil or Animal Fat Oil, Which is More Conducive to Cardiovascular Health Among the Elderly in China?

Our present study aimed to investigate the relationship between cooking oil types and atherosclerotic cardiovascular disease (ASCVD) and to reveal which cooking oil is more beneficial to cardiovascular health in older Chinese. This study relies on cross-section data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) in the 2018 wave. A total of 15,874 elderly Chinese over 65 years old were included in our analysis. Logistic regression analysis was used to assess the association between cooking oil types and ASCVD. Of the 15,874 elderly people, 13,709 cooked with vegetable/gingili oil, with an average age [SD] of 84.47 [11.51] years; 1533 cooked with lard/other animal fat oils, with an average age [SD] of 85.90 [11.72] years. 3918 of those who cooked with vegetable/gingili oil had ASCVD, and 249 of those who cooked with lard/other animal fat oils had ASCVD. The prevalence of ASCVD in vegetable/gingili oil users (31.68%) was higher than that in lard/other animal fat oil users (17.46%). Compared with lard/other animal fat users, the multivariate-adjusted model indicated that vegetable oil/sesame oil users were significantly associated with a higher risk of ASCVD (OR = 2.19; 95%CI, 1.90-2.53). Our study found that cooking with lard/other animal fat oil is more beneficial to cardiovascular health in older Chinese. Dietary guidelines should seriously consider the health effects of substituting vegetable/gingili oil for lard/other animal fat oil for different populations.

The association between dietary fats and the incidence risk of cardiovascular outcomes: Tehran Lipid and Glucose Study

Background

The association between dietary fats and the risk of cardiovascular disease (CVD) is under debate. We aimed to determine the potential effects of dietary saturated fats (SFA), mono-unsaturated (MUFA) and poly-unsaturated (PUFA) fatty acids on the occurrence of CVD in an adult Asian population.

Methods

This study was conducted within the framework of the Tehran Lipid and Glucose Study on 2809 CVD-free adults, aged ≥ 19 years. Dietary intakes of fats were estimated using a validated 168-items semi-quantitative food frequency questionnaire, at baseline. Adjusted hazard ratios and 95% confidence intervals of CVD were calculated in tertile categories of dietary fats. The risk of CVD was estimated with multivariable Cox regression for the substitution of total fat or SFA with other macronutrients.

Results

During 10.6 years of follow up, the incidence rate of CVD events was 7.1%. Mean (± SD) age of the participants was 39 (± 14) years and 43.9% were men. Total fat, animal and plant sources of fats were not associated with risk of CVD events. No significant associations were found between total SFA, lauric acid, myristic acid, stearic acid, palmitic acid as well as MUFA and PUFA and CVD incidence. Substitutions of total fats or SFA with other macronutrients were not associated with CVD risk.

Conclusions

In this study, no significant associations were found between dietary fats and CVD risk. Considering the emerging body of literature that suggests no association between fats and CVD risk, reconsideration of dietary recommendations regarding low fat diets to prevent CVD, seems to be essential.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12986-021-00624-6.

Association of carbohydrate and saturated fat intake with cardiovascular disease and mortality in Australian women

BACKGROUND

Conflicting evidence surrounds the effect of dietary macronutrient intake (fat, carbohydrate and protein) on cardiovascular disease (CVD), particularly in women.

METHODS

Women (aged 50-55 years) were recruited into the Australian Longitudinal Study on Women's Health. Women were divided into quintiles according to their carbohydrate and saturated fat intake as a percentage of total energy intake (TEI). The primary endpoint was new-onset CVD (heart disease/stroke). Secondary endpoints included all-cause mortality, incident hypertension, obesity and/or diabetes mellitus. Multivariate logistic regression models assessed for associations with the primary and secondary endpoints, with adjustment for confounders.

RESULTS

A total of 9899 women (mean age 52.5±1.5 years) were followed for 15 years, with 1199 incident CVD and 470 deaths. On multivariable analysis, higher carbohydrate intake was associated with lower CVD risk (p_trend<0.01), with the lowest CVD risk for quintile 3 (41.0%-44.3% energy as carbohydrate) versus quintile 1 (<37.1% energy as carbohydrate) (OR 0.56, 95% CI 0.35 to 0.91, p=0.02). There was no significant association between carbohydrate intake and mortality (p_trend=0.69) or between saturated fat intake and CVD (p_trend=0.29) or mortality (p_trend=0.25). Both increasing saturated fat and carbohydrate intake were significantly inversely associated with hypertension, diabetes mellitus and obesity (p_trend<0.01 for all).

CONCLUSIONS

In middle-aged Australian women, moderate carbohydrate intake (41.0%-44.3% of TEI) was associated with the lowest risk of CVD, without an effect on total mortality. Increasing saturated fat intake was not associated with CVD or mortality and instead correlated with lower rates of diabetes, hypertension and obesity.

Fat, Sugar or Gut Microbiota in Reducing Cardiometabolic Risk: Does Diet Type Really Matter?

The incidence of cardiometabolic diseases, such as obesity, diabetes, and cardiovascular diseases, is constantly rising. Successful lifestyle changes may limit their incidence, which is why researchers focus on the role of nutrition in this context. The outcomes of studies carried out in past decades have influenced dietary guidelines, which primarily recommend reducing saturated fat as a therapeutic approach for cardiovascular disease prevention, while limiting the role of sugar due to its harmful effects. On the other hand, a low-carbohydrate diet (LCD) as a method of treatment remains controversial. A number of studies on the effect of LCDs on patients with type 2 diabetes mellitus proved that it is a safe and effective method of dietary management. As for the risk of cardiovascular diseases, the source of carbohydrates and fats corresponds with the mortality rate and protective effect of plant-derived components. Additionally, some recent studies have focused on the gut microbiota in relation to cardiometabolic diseases and diet as one of the leading factors affecting microbiota composition. Unfortunately, there is still no precise answer to the question of which a single nutrient plays the most important role in reducing cardiometabolic risk, and this review article presents the current state of the knowledge in this field.

Dietary total fat, fatty acids intake, and risk of cardiovascular disease: a dose-response meta-analysis of cohort studies

BACKGROUND

Several epidemiological studies have investigated the association between dietary fat intake and cardiovascular disease. However, dietary recommendations based on systematic review and meta-analysis might be more credible.

METHODS AND RESULTS

Pubmed, Embase and Cochrane library were searched up to July 1st 2018 for cohort studies reporting associations of dietary fat intake and risk of CVDs. By comparing the highest vs. the lowest categories of fat or fatty acids intake, we found that higher dietary trans fatty acids (TFA) intake was associated with increased risk of CVDs [RR:1.14(1.08-1.21)]. However, no association was observed between total fat, monounsaturated fatty acids (MUFA), saturated fatty acids (SFA), and polyunsaturated fatty acids (PUFA), and risk of CVDs. Subgroup analysis found a cardio-protective effect of PUFA in the studies that has been followed up more than 10 years [0.95(0.91-0.99), I2 = 62.4%]. Dose-response analysis suggested that the risk of CVDs increased 16% [1.16 (1.07-1.25), Plinearity = 0.033] for an increment of 2% energy/day of TFA intake.

CONCLUSIONS

This current meta-analysis of cohort studies suggested that total fat, SFA, MUFA, and PUFA intake were not associated with the risk of cardiovascular disease. However, we found that higher TFA intake is associated with greater risk of CVDs in a dose-response fashion. Furthermore, the subgroup analysis found a cardio-protective effect of PUFA in studies followed up for more than 10 years.

Fat, Sugar, Whole Grains and Heart Disease: 50 Years of Confusion

During the 1970s some investigators proposed that refined carbohydrates, especially sugar and a low intake of dietary fiber, were major factors in coronary heart disease (CHD). This suggestion was eclipsed by the belief that an excess intake of saturated fatty acids (SFA) was the key dietary factor, a view that prevailed from roughly 1974 to 2014. Findings that have accumulated since 1990 inform us that the role of SFA in the causation of CHD has been much exaggerated. A switch from SFA to refined carbohydrates does not lower the ratio of total cholesterol to HDL-cholesterol in the blood and therefore does not prevent CHD. A reduced intake of SFA combined with an increased intake of polyunsaturated fatty acids lowers the ratio of total cholesterol to HDL-cholesterol; this may reduce the risk of CHD. The evidence linking carbohydrate-rich foods with CHD has been steadily strengthening. Refined carbohydrates, especially sugar-sweetened beverages, increase the risk of CHD. Conversely, whole grains and cereal fiber are protective. An extra one or 2 servings per day of these foods increases or decreases risk by approximately 10% to 20%.

Behavioural Risk Factors in Mid-Life Associated with Successful Ageing, Disability, Dementia and Frailty in Later Life: A Rapid Systematic Review

BACKGROUND

Smoking, alcohol consumption, poor diet and low levels of physical activity significantly contribute to the burden of illness in developed countries. Whilst the links between specific and multiple risk behaviours and individual chronic conditions are well documented, the impact of these behaviours in mid-life across a range of later life outcomes has yet to be comprehensively assessed. This review aimed to provide an overview of behavioural risk factors in mid-life that are associated with successful ageing and the primary prevention or delay of disability, dementia, frailty and non-communicable chronic conditions.

METHODS

A literature search was conducted to identify cohort studies published in English since 2000 up to Dec 2014. Multivariate analyses and a minimum follow-up of five years were required for inclusion. Two reviewers screened titles, abstracts and papers independently. Studies were assessed for quality. Evidence was synthesised by mid-life behavioural risk for a range of late life outcomes.

FINDINGS

This search located 10,338 individual references, of which 164 are included in this review. Follow-up data ranged from five years to 36 years. Outcomes include dementia, frailty, disability and cardiovascular disease. There is consistent evidence of beneficial associations between mid-life physical activity, healthy ageing and disease outcomes. Across all populations studied there is consistent evidence that mid-life smoking has a detrimental effect on health. Evidence specific to alcohol consumption was mixed. Limited, but supportive, evidence was available relating specifically to mid-life diet, leisure and social activities or health inequalities.

CONCLUSIONS

There is consistent evidence of associations between mid-life behaviours and a range of late life outcomes. The promotion of physical activity, healthy diet and smoking cessation in all mid-life populations should be encouraged for successful ageing and the prevention of disability and chronic disease.

Evidence-Based Guideline of the German Nutrition Society: Fat Intake and Prevention of Selected Nutrition-Related Diseases

As nutrition-related chronic diseases have become more and more frequent, the importance of dietary prevention has also increased. Dietary fat plays a major role in human nutrition, and modification of fat and/or fatty acid intake could have a preventive potential. The aim of the guideline of the German Nutrition Society (DGE) was to systematically evaluate the evidence for the prevention of the widespread diseases obesity, type 2 diabetes mellitus, dyslipoproteinaemia, hypertension, metabolic syndrome, coronary heart disease (CHD), stroke, and cancer through the intake of fat or fatty acids. The main results can be summarized as follows: it was concluded with convincing evidence that a reduced intake of total and saturated fat as well as a larger intake of polyunsaturated fatty acids (PUFA) at the expense of saturated fatty acids (SFA) reduces the concentration of total and low-density lipoprotein cholesterol in plasma. Furthermore, there is convincing evidence that a high intake of trans fatty acids increases risk of dyslipoproteinaemia and that a high intake of long-chain polyunsaturated n-3 fatty acids reduces the triglyceride concentration in plasma. A high fat intake increases the risk of obesity with probable evidence when total energy intake is not controlled for (ad libitum diet). When energy intake is controlled for, there is probable evidence for no association between fat intake and risk of obesity. A larger intake of PUFA at the expense of SFA reduces risk of CHD with probable evidence. Furthermore, there is probable evidence that a high intake of long-chain polyunsaturated n-3 fatty acids reduces risk of hypertension and CHD. With probable evidence, a high trans fatty acid intake increases risk of CHD. The practical consequences for current dietary recommendations are described at the end of this article.

Intake of saturated and trans unsaturated fatty acids and risk of all cause mortality, cardiovascular disease, and type 2 diabetes: systematic review and meta-analysis of observational studies

OBJECTIVE

To systematically review associations between intake of saturated fat and trans unsaturated fat and all cause mortality, cardiovascular disease (CVD) and associated mortality, coronary heart disease (CHD) and associated mortality, ischemic stroke, and type 2 diabetes.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Medline, Embase, Cochrane Central Registry of Controlled Trials, Evidence-Based Medicine Reviews, and CINAHL from inception to 1 May 2015, supplemented by bibliographies of retrieved articles and previous reviews.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Observational studies reporting associations of saturated fat and/or trans unsaturated fat (total, industrially manufactured, or from ruminant animals) with all cause mortality, CHD/CVD mortality, total CHD, ischemic stroke, or type 2 diabetes.

DATA EXTRACTION AND SYNTHESIS

Two reviewers independently extracted data and assessed study risks of bias. Multivariable relative risks were pooled. Heterogeneity was assessed and quantified. Potential publication bias was assessed and subgroup analyses were undertaken. The GRADE approach was used to evaluate quality of evidence and certainty of conclusions.

RESULTS

For saturated fat, three to 12 prospective cohort studies for each association were pooled (five to 17 comparisons with 90,501-339,090 participants). Saturated fat intake was not associated with all cause mortality (relative risk 0.99, 95% confidence interval 0.91 to 1.09), CVD mortality (0.97, 0.84 to 1.12), total CHD (1.06, 0.95 to 1.17), ischemic stroke (1.02, 0.90 to 1.15), or type 2 diabetes (0.95, 0.88 to 1.03). There was no convincing lack of association between saturated fat and CHD mortality (1.15, 0.97 to 1.36; P=0.10). For trans fats, one to six prospective cohort studies for each association were pooled (two to seven comparisons with 12,942-230,135 participants). Total trans fat intake was associated with all cause mortality (1.34, 1.16 to 1.56), CHD mortality (1.28, 1.09 to 1.50), and total CHD (1.21, 1.10 to 1.33) but not ischemic stroke (1.07, 0.88 to 1.28) or type 2 diabetes (1.10, 0.95 to 1.27). Industrial, but not ruminant, trans fats were associated with CHD mortality (1.18 (1.04 to 1.33) v 1.01 (0.71 to 1.43)) and CHD (1.42 (1.05 to 1.92) v 0.93 (0.73 to 1.18)). Ruminant trans-palmitoleic acid was inversely associated with type 2 diabetes (0.58, 0.46 to 0.74). The certainty of associations between saturated fat and all outcomes was "very low." The certainty of associations of trans fat with CHD outcomes was "moderate" and "very low" to "low" for other associations.

CONCLUSIONS

Saturated fats are not associated with all cause mortality, CVD, CHD, ischemic stroke, or type 2 diabetes, but the evidence is heterogeneous with methodological limitations. Trans fats are associated with all cause mortality, total CHD, and CHD mortality, probably because of higher levels of intake of industrial trans fats than ruminant trans fats. Dietary guidelines must carefully consider the health effects of recommendations for alternative macronutrients to replace trans fats and saturated fats.

Dietary saturated fat intake and atherosclerotic vascular disease mortality in elderly women: a prospective cohort study

BACKGROUND

The reduction of saturated fatty acid (SFA) intake has been the basis of long-standing dietary recommendations. However, recent epidemiologic studies have reported conflicting evidence in the relation between SFA consumption and risk of atherosclerotic vascular disease (ASVD) mortality.

OBJECTIVE

We investigated the association of SFA intake with serum lipid profiles and ASVD mortality in a population-based 10-y cohort study.

DESIGN

At baseline (1998) 1469 women living in Perth, Western Australia, with a mean ± SD age of 75.2 ± 2.7 y had SFA intake measured by using a validated food-frequency questionnaire. Outcome data were serum lipids at baseline and ASVD deaths over 10 y (13,649 person-years of follow-up), retrieved from the Western Australian Data Linkage System. Other risk factors for ASVD were assessed and adjusted for in multivariable analyses.

RESULTS

ASVD deaths occurred in 9.1% (134) of participants. The highest quartile of SFA intake (>31.28 g/d) had an ~16% cumulative mortality risk compared with ~5% in the lowest quartile (<17.39 g/d) (HR: 3.07; 95% CI: 1.54, 6.11; P = 0.001). Baseline SFA intake was associated with baseline serum total and LDL cholesterol in multivariable-adjusted models (β: 0.199, SE: 0.056, P < 0.001 and β: 0.190, SE: 0.051, P < 0.001, respectively). However, baseline serum total and LDL cholesterol were not associated with ASVD mortality.

CONCLUSIONS

High SFA intake was associated with the risk of ASVD mortality in this population of elderly women. Although there was a strong positive association between SFA intake and LDL cholesterol, LDL cholesterol was not associated with ASVD mortality in this cohort. Nevertheless, these data support dietary advice to reduce SFA intake.

Monounsaturated fatty acids, olive oil and health status: a systematic review and meta-analysis of cohort studies

Background

The aim of the present meta-analysis of cohort studies was to focus on monounsaturated fat (MUFA) and cardiovascular disease, cardiovascular mortality as well as all-cause mortality, and to distinguish between the different dietary sources of MUFA.

Methods

Literature search was performed using the electronic databases PUBMED, and EMBASE until June 2nd, 2014. Study specific risk ratios and hazard ratios were pooled using a inverse variance random effect model.

Results

Thirty-two cohort studies (42 reports) including 841,211 subjects met the objectives and were included. The comparison of the top versus bottom third of the distribution of a combination of MUFA (of both plant and animal origin), olive oil, oleic acid, and MUFA:SFA ratio in each study resulted in a significant risk reduction for: all-cause mortality (RR: 0.89, 95% CI 0.83, 0.96, p = 0.001; I² = 64%), cardiovascular mortality (RR: 0.88, 95% CI 0.80, 0.96, p = 0.004; I² = 50%), cardiovascular events (RR: 0.91, 95% CI 0.86, 0.96, p = 0.001; I² = 58%), and stroke (RR: 0.83, 95% CI 0.71, 0.97, p = 0.02; I² = 70%). Following subgroup analyses, significant associations could only be found between higher intakes of olive oil and reduced risk of all-cause mortality, cardiovascular events, and stroke, respectively. The MUFA subgroup analyses did not reveal any significant risk reduction.

Conclusion

The results indicate an overall risk reduction of all-cause mortality (11%), cardiovascular mortality (12%), cardiovascular events (9%), and stroke (17%) when comparing the top versus bottom third of MUFA, olive oil, oleic acid, and MUFA:SFA ratio. MUFA of mixed animal and vegetable sources per se did not yield any significant effects on these outcome parameters. However, only olive oil seems to be associated with reduced risk. Further research is necessary to evaluate specific sources of MUFA (i.e. plant vs. animal) and cardiovascular risk.

Electronic supplementary material

The online version of this article (doi:10.1186/1476-511X-13-154) contains supplementary material, which is available to authorized users.

Plasma fatty acid composition and incident ischemic stroke in middle-aged adults: the Atherosclerosis Risk in Communities (ARIC) Study

BACKGROUND

The association of individual fatty acids with ischemic stroke has not been thoroughly studied, and results have been inconsistent. Few prospective studies have systematically explored the association of biomarkers of fatty acid intake with stroke. The aim of this study was to explore which individual plasma fatty acids would be associated with higher risk of ischemic stroke among whites.

METHODS

We studied 3,870 white men and women from the Minneapolis field center of the Atherosclerosis Risk in Communities (ARIC) Study, aged 45-64 years at baseline (1987-1989), who had plasma cholesterol ester (CE) and phospholipid (PL) fatty acids measured. Participants were followed through 2008 for incident ischemic stroke. Hazard ratios (HRs) with 95% confidence intervals (CIs) across quartiles of each fatty acid, measured as the percentage of total fatty acids, were calculated using the Cox proportional hazards model.

RESULTS

During a maximum of 22 years of follow-up, we identified 168 cases of ischemic stroke. After adjustment for age and sex, plasma levels of saturated fatty acids were associated positively: HR (95% CI) of the highest versus the lowest quartile for CE fraction was 1.93 (1.23-3.04, p for trend = 0.01) and that for PL fraction was 1.64 (1.05-2.57, p for trend = 0.03). There was also a positive linear association with monounsaturated fatty acids, especially with palmitoleic acid: HR (95% CI) of the highest versus the lowest quartile for CE fraction was 1.86 (1.20-2.87, p for trend = 0.003) and that for PL fraction was 1.52 (0.99-2.34, p for trend = 0.005). No associations of ω-3 and ω-6 polyunsaturated fatty acids with ischemic stroke were observed, but linoleic acid was inversely and nonlinearly associated with ischemic stroke: HR (95% CI) of the highest versus the lowest quartile for CE fraction was 0.64 (0.43-0.97, p for trend = 0.13) and that for PL fraction was 0.69 (0.45-1.05, p for trend = 0.24). These associations were generally unchanged after adjustment for cardiovascular risk factors.

CONCLUSIONS

In this US cohort of whites, we found significant positive associations of plasma saturated and monounsaturated fatty acids, especially of palmitoleic acid, with ischemic stroke. We also found an inverse nonlinear association between linoleic acid and ischemic stroke.

Comparison of predictive performance of various fatty acids for the risk of cardiovascular disease events and all-cause deaths in a community-based cohort

BACKGROUND

The issue of whether saturated fats and trans fats are superior predictors of all-cause death and cardiovascular disease than n-3 polyunsaturated fatty acids, such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), remains a matter of contention. Furthermore, few studies have examined the relationship between fatty acids and the outcomes of cardiovascular disease (CVD) in Asian populations. The aim of this study was to compare the effectiveness of various plasma fatty acids as predictors for all-cause death and CVD events in an ethnic Chinese population.

METHODS

This study assembled a community-based prospective cohort, comprising 1833 participants (60.6 ± 10.5 yrs, 44.5% women) who underwent a comprehensive evaluation of fatty acids in blood using gas chromatography. None of the subjects had a history of CVD at the time of recruitment.

RESULTS

A total of 568 individuals died and 275 individuals developed CVD during the follow-up period (median of 9.6 years; interquartile range of 8.9-10.5 years). Following adjustment for established cardiovascular risk factors, the relative risk of all-cause death in the highest quartile, compared with the lowest quartile, was 1.33 for saturated fats (95% confidence interval [CI], 1.01-1.75, test for trend, P = 0.015), 1.71 for trans fats (95% CI, 1.27-2.31, test for trend, P = 0.0003), 0.77 for EPA (95% CI, 0.59-1.00, test for trend, P = 0.048), and 0.89 for DHA (95% CI, 0.68-1.18, test for trend, P = 0.354). Similar patterns were observed for CVD events. Trans fats presented the largest area under the receiver operator characteristic curve (0.740, 95% CI, 0.716-0.766) for the prediction of all-cause death. A mutually adjusted two-marker model indicated that saturated fats and trans fats were significant predictors of all-cause death and CVD; however, the other fatty acids were not. In addition, trans fats presented the greatest improvement in net reclassification for all-cause death (7.7%, P = 0.003), followed by EPA (3.8%, P = 0.033). Saturated fats presented the greatest improvement in net reclassification for CVD events (5.6%, P = 0.039).

CONCLUSIONS

Our data provides strong evidence to support that plasma saturated fats and trans fats can predict all-cause death and CVD more effectively than other fatty acid markers.

In type 2 diabetes, randomisation to advice to follow a low-carbohydrate diet transiently improves glycaemic control compared with advice to follow a low-fat diet producing a similar weight loss

AIMS/HYPOTHESIS

The study aimed to compare the effects of a 2 year intervention with a low-fat diet (LFD) or a low-carbohydrate diet (LCD), based on four group meetings to achieve compliance.

METHODS

This was a prospective randomised parallel trial involving 61 adults with type 2 diabetes consecutively recruited in primary care and randomised by drawing ballots. Patients that did not speak Swedish could not be recruited. The primary outcomes in this non-blinded study were weight and HbA(1c). Patients on the LFD aimed for 55-60 energy per cent (E%) and those on LCD for 20 E% from carbohydrate.

RESULTS

The mean BMI and HbA(1c) of the participants were 32.7 ± 5.4 kg/m(2) and 57.0 ± 9.2 mmol/mol, respectively. No patients were lost to follow-up. Weight loss did not differ between groups and was maximal at 6 months: LFD -3.99 ± 4.1 kg (n=31); LCD -4.31 ± 3.6 kg (n=30); p < 0.001 within groups. At 24 months, patients on the LFD had lost -2.97 ± 4.9 kg and those on LCD -2.34 ± 5.1 kg compared with baseline (p = 0.002 and p = 0.020 within groups, respectively). HbA(1c) fell in the LCD group only (LCD at 6 months -4.8 ± 8.3 mmol/mol, p = 0.004, at 12 months -2.2 ± 7.7 mmol/mol, p = 0.12; LFD at 6 months -0.9 ± 8.8 mmol/mol, p = 0.56). At 6 months, HDL-cholesterol had increased with the LCD (from 1.13 ± 0.33 mmol/l to 1.25 ± 0.47 mmol/l, p = 0.018) while LDL-cholesterol did not differ between groups. Insulin doses were reduced in the LCD group (0 months, LCD 42 ± 65 E, LFD 39 ± 51 E; 6 months, LCD 30 ± 47 E, LFD 38 ± 48 E; p = 0.046 for between-group change).

CONCLUSIONS/INTERPRETATION

Weight changes did not differ between the diet groups, while insulin doses were reduced significantly more with the LCD at 6 months, when compliance was good. Thus, aiming for 20% of energy intake from carbohydrates is safe with respect to cardiovascular risk compared with the traditional LFD and this approach could constitute a treatment alternative.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01005498

FUNDING

University Hospital of Linköping Research Funds, Linköping University, the County Council of Östergötland, and the Diabetes Research Centre of Linköping University.

Dietary fiber and saturated fat intake associations with cardiovascular disease differ by sex in the Malmö Diet and Cancer Cohort: a prospective study

BACKGROUND

The aim of the study was to examine associations between intake of macronutrients and dietary fiber and incident ischemic cardiovascular disease (iCVD) in men and women.

METHODS

We used data from 8,139 male and 12,535 female participants (aged 44-73 y) of the Swedish population-based Malmö Diet and Cancer cohort. The participants were without history of CVD and diabetes mellitus, and had reported stable dietary habits in the study questionnaire. Diet was assessed by a validated modified diet history method, combining a 7-d registration of cooked meals and cold beverages, a 168-item food questionnaire (covering other foods and meal patterns), and a 1-hour diet interview. Sociodemographic and lifestyle data were collected by questionnaire. iCVD cases, which included coronary events (myocardial infarctions or deaths from chronic ischemic heart disease) and ischemic strokes, were ascertained via national and local registries. Nutrient-disease associations were examined by multivariate Cox regressions.

RESULTS

During a mean follow-up of 13.5 years, we identified 1,089 male and 687 female iCVD cases. High fiber intakes were associated with lower incidence rates of iCVD in women and of ischemic stroke in men. In post-hoc analysis, we discovered statistically significant interactions between intake of fiber and saturated fat; these interactions also differed between men and women (p<0.001).

CONCLUSIONS

In this well-defined population, a high fiber intake was associated with lower risk of iCVD, but there were no robust associations between other macronutrients and iCVD risk. Judging from this study, gender-specific nutrient analysis may be preferable in epidemiology.

Dietary fats and dietary cholesterol and risk of stroke in women

BACKGROUND

Whether intakes of dietary fat and cholesterol are associated with risk of stroke remain unclear. We examined the associations between intakes of total fat, specific types of fat, and cholesterol and risk of stroke in a prospective cohort of women.

METHODS

The study population consisted of 34,670 women, aged 49-83 years, in the Swedish Mammography Cohort who were free of cardiovascular disease and completed a food-frequency questionnaire in 1997. Cox proportional hazard regression models were used to estimate relative risks (RR) with 95% confidence intervals (CI).

RESULTS

During a mean follow-up of 10.4 years, we ascertained 1680 stroke events, including 1310 cerebral infarctions, 233 hemorrhagic strokes, and 137 unspecified strokes. After adjustment for other stroke risk factors, intake of long-chain omega-3 polyunsaturated fatty acids (PUFA) was inversely associated with risk of total stroke. The multivariable RR of total stroke for the highest compared with the lowest quintile of long-chain omega-3 PUFA intake was 0.84 (95% CI, 0.72-0.99; P for trend=0.04). Dietary cholesterol was positively associated with risk of total stroke (highest versus lowest quintile: RR=1.20; 95% CI, 1.00-1.44; P for trend=0.01) and cerebral infarction (corresponding RR=1.29; 95% CI, 1.05-1.58; P for trend=0.004). Total fat, saturated fat, monounsaturated fat, polyunsaturated fat, α-linolenic acid, and omega-6 PUFA intakes were not associated with stroke.

CONCLUSIONS

These findings suggest that intake of long-chain omega-3 PUFAs is inversely associated with risk of stroke, whereas dietary cholesterol is positively associated with risk.

Dietary Carbohydrate Modifies the Inverse Association Between Saturated Fat Intake and Cholesterol on Very Low-Density Lipoproteins

We aimed to investigate the relationship between dietary saturated fat on fasting triglyceride (TG) and cholesterol levels, and any mediation of this relationship by dietary carbohydrate intake. Men and women in the NHLBI Genetics of Lipid-Lowering Drugs and Diet Network (GOLDN) study (n = 1036, mean age ± SD = 49 ± 16 y) were included. Mixed linear models were run with saturated fat as a predictor variable and fasting TG, very low density lipoprotein cholesterol (VLDL-C), low density cholesterol (LDL-C) and high density cholesterol (HDL-C) as separate outcome variables. Subsequent models were run which included dietary carbohydrate as a predictor variable, and an interaction term between saturated fat and carbohydrate. All models controlled for age, sex, BMI, blood pressure and dietary covariates. In models that included only saturated fat as a predictor, saturated fat did not show significant associations with fasting lipids. When carbohydrate intake and an interaction term between carbohydrates and saturated fat intake was included, carbohydrate intake did not associate with lipids, but there was an inverse relationship between saturated fat intake and VLDL-C (P = 0.01) with a significant interaction (P = 0.01) between saturated fat and carbohydrate with regard to fasting VLDL-C concentrations. Similar results were observed for fasting TG levels. We conclude that, when controlling for carbohydrate intake, higher saturated fat was associated with lower VLDL-C and TGs. This was not the case at higher intakes of carbohydrate. This has important implications for dietary advice aimed at reducing TG and VLDL-C levels.

Saturated fatty acids and risk of coronary heart disease: modulation by replacement nutrients

Despite the well-established observation that substitution of saturated fats for carbohydrates or unsaturated fats increases low-density lipoprotein (LDL) cholesterol in humans and animal models, the relationship of saturated fat intake to risk for atherosclerotic cardiovascular disease in humans remains controversial. A critical question is what macronutrient should be used to replace saturated fat. Substituting polyunsaturated fat for saturated fat reduces LDL cholesterol and the total cholesterol to high-density lipoprotein cholesterol ratio. However, replacement of saturated fat by carbohydrates, particularly refined carbohydrates and added sugars, increases levels of triglyceride and small LDL particles and reduces high-density lipoprotein cholesterol, effects that are of particular concern in the context of the increased prevalence of obesity and insulin resistance. Epidemiologic studies and randomized clinical trials have provided consistent evidence that replacing saturated fat with polyunsaturated fat, but not carbohydrates, is beneficial for coronary heart disease. Therefore, dietary recommendations should emphasize substitution of polyunsaturated fat and minimally processed grains for saturated fat.

Dietary intake of saturated fatty acids and mortality from cardiovascular disease in Japanese: the Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC) Study

BACKGROUND

Prospective epidemiologic studies have generated mixed results regarding the association between saturated fatty acid (SFA) intake and risk of ischemic heart disease (IHD) and stroke. These associations have not been extensively studied in Asians.

OBJECTIVE

The aim of this study was to test the hypothesis that SFA intake is associated with the risk of cardiovascular disease mortality in Japanese whose average SFA intake is low.

DESIGN

The Japan Collaborative Cohort Study for Evaluation of Cancer Risk (JACC Study) comprised 58,453 Japanese men and women who completed a food-frequency questionnaire. Participants were aged 40-79 y at baseline (1988-1990) and were followed up for 14.1 y. Associations of energy-adjusted SFA intake with mortality from stroke (intraparenchymal and subarachnoid hemorrhages and ischemic stroke) and heart diseases (IHD, cardiac arrest, and heart failure) were examined after adjustment for age, sex, and cardiovascular disease risk and dietary factors.

RESULTS

We observed inverse associations of SFA intake with mortality from total stroke [n = 976; multivariable hazard ratio (95% CI) for highest compared with lowest quintiles: 0.69 (0.53, 0.89); P for trend = 0.004], intraparenchymal hemorrhage [n = 224; 0.48 (0.27, 0.85); P for trend = 0.03], and ischemic stroke [n = 321; 0.58 (0.37, 0.90); P for trend = 0.01]. No multivariable-adjusted associations were observed between SFA and mortality from subarachnoid hemorrhage [n = 153; 0.91 (0.46, 1.80); P for trend = 0.47] and heart disease [n = 836; 0.89 (0.68, 1.15); P for trend = 0.59].

CONCLUSION

SFA intake was inversely associated with mortality from total stroke, including intraparenchymal hemorrhage and ischemic stroke subtypes, in this Japanese cohort.

Dairy products and plasma cholesterol levels

Cholesterol synthesized in the body or ingested is an essential lipid component for human survival from our earliest life. Newborns ingest about 3-4 times the amount per body weight through mother's milk compared to the dietary intake of adults. A birth level of 1.7 mmol/L plasma total cholesterol will increase to 4-4.5 mmol/L during the nursing period and continue to increase from adulthood around 40% throughout life. Coronary artery disease and other metabolic disorders are strongly associated with low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol as well as triacylglycerol concentration. Milk fat contains a broad range of fatty acids and some have a negative impact on the cholesterol rich lipoproteins. The saturated fatty acids (SFAs), such as palmitic acid (C16:0), myristic acid (C14:0), and lauric acid (C12:0), increase total plasma cholesterol, especially LDL, and constitute 11.3 g/L of bovine milk, which is 44.8% of total fatty acid in milk fat. Replacement of dairy SFA and trans-fatty acids with polyunsaturated fatty acids decreases plasma cholesterol, especially LDL cholesterol, and is associated with a reduced risk of cardiovascular disease. Available data shows different effects on lipoproteins for different dairy products and there is uncertainty as to the impact a reasonable intake amount of dairy items has on cardiovascular risk. The aim of this review is to elucidate the effect of milk components and dairy products on total cholesterol, LDL, HDL, and the LDL/HDL quotients. Based on eight recent randomized control trials of parallel or cross-over design and recent reviews it can be concluded that replacement of saturated fat mainly (but not exclusively) derived from high-fat dairy products with low-fat dairy products lowers LDL/HDL cholesterol and total/HDL cholesterol ratios. Whey, dairy fractions enriched in polar lipids, and techniques such as fermentation, or fortification of cows feeding can be used to produce dairy products with more beneficial effects on plasma lipid profile.

Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease

BACKGROUND

A reduction in dietary saturated fat has generally been thought to improve cardiovascular health.

OBJECTIVE

The objective of this meta-analysis was to summarize the evidence related to the association of dietary saturated fat with risk of coronary heart disease (CHD), stroke, and cardiovascular disease (CVD; CHD inclusive of stroke) in prospective epidemiologic studies.

DESIGN

Twenty-one studies identified by searching MEDLINE and EMBASE databases and secondary referencing qualified for inclusion in this study. A random-effects model was used to derive composite relative risk estimates for CHD, stroke, and CVD.

RESULTS

During 5-23 y of follow-up of 347,747 subjects, 11,006 developed CHD or stroke. Intake of saturated fat was not associated with an increased risk of CHD, stroke, or CVD. The pooled relative risk estimates that compared extreme quantiles of saturated fat intake were 1.07 (95% CI: 0.96, 1.19; P = 0.22) for CHD, 0.81 (95% CI: 0.62, 1.05; P = 0.11) for stroke, and 1.00 (95% CI: 0.89, 1.11; P = 0.95) for CVD. Consideration of age, sex, and study quality did not change the results.

CONCLUSIONS

A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat.

Food choices and coronary heart disease: a population based cohort study of rural Swedish men with 12 years of follow-up

Coronary heart disease is associated with diet. Nutritional recommendations are frequently provided, but few long term studies on the effect of food choices on heart disease are available. We followed coronary heart disease morbidity and mortality in a cohort of rural men (N = 1,752) participating in a prospective observational study. Dietary choices were assessed at baseline with a 15-item food questionnaire. 138 men were hospitalized or deceased owing to coronary heart disease during the 12 year follow-up. Daily intake of fruit and vegetables was associated with a lower risk of coronary heart disease when combined with a high dairy fat consumption (odds ratio 0.39, 95% CI 0.21–0.73), but not when combined with a low dairy fat consumption (odds ratio 1.70, 95% CI 0.97–2.98). Choosing wholemeal bread or eating fish at least twice a week showed no association with the outcome.

Pivotal role of inflammation in vascular endothelial dysfunction of hyperlipidemic rabbit and effects by atorvastatin

AIMS

To evaluate the role of inflammation in vascular endothelial function of hyperlipidemic rabbits and atorvastatin's effects on it.

METHODS

22 rabbits were divided into high-fat diet and atorvastatin plus high-fat diet group. Basic levels of total and low-density lipoprotein cholesterol, triglyceride, C-reactive protein (CRP), interleukin-6 (IL-6), nitric oxide (NO), endothelin-1 (ET-1), fasting blood glucose (FBG), insulin and endothelial function were measured when grouping. Eight weeks later, all above parameters were remeasured and repeated again at days 1, 4 and 7 after atorvastatin withdrawal.

RESULTS

Eight-week high-fat diet could not cause the changes of FBG and insulin, but significantly induce increased blood lipids as well as inflammatory markers, imbalance between ET-1 and NO, and direct endothelial dysfunction, which could be significantly improved by atorvastatin therapy but could not be well controlled to near baseline. Abrupt withdrawal of atorvastatin caused sharp increase of inflammatory markers and endothelial dysfunction at days 4 and 7 after atorvastatin withdrawal independent of the changes of blood lipids.

CONCLUSIONS

High-fat diet could cause endothelial dysfunction associated with inflammation, and atorvastatin could counter-regulate it. Sudden withdrawal of statins could induce rebound of inflammatory response and endothelial dysfunction independent of changes of lipids, which may be responsible for increased cardiovascular events in patients with coronary artery disease after withdrawing statins.

On criticism in bio-medical research--a tribute to Uffe Ravnskov

The great importance of criticism in science--and its ups-and-downs due to human prejudices and emotions--is discussed in a historical perspective. Towards such a background, attempts are made to evaluate present controversies concerning the widely assumed cause-effect relations between diet-adipositas per se and disorders, like diabetes 2 and atherosclerosis. Seen from a physiological angle, it appears that the real culprits are to a great extent of a different nature, though easily overlooked in e.g. mass screenings. Thus, the human brain reacts to the many mental challenges of modern hectic-competitive life with the same protective response patterns as seen in all mammals, i.e. with defeat- and/or defence-reactions. Here the hypothalamic-hypophyseal-glucocorticoid axis, respectively the hypothalamic-sympatho-adrenomedullary one, serves to support the associated behavioural expressions. Experiments in group-living mammals show how mentally induced prolonged engagements of these neuro-endocrine links end up in serious metabolic and organ-system disturbances, also if factors like diet are kept unchanged. To this comes that in 'civilized' man the respective behavioural expressions are commonly suppressed, whereby most 'inside' neuro-hormonally induced changes occur in vain. An aggravating component is inherent in generally dwindling physical activity, implying that the many bodily and mental advantages of regular exercise are much reduced. Towards such a background, it appears strange that 'The metabolic syndrome' and its sequalae are not even more common today.