Macadamia nut effects on cardiometabolic risk factors: a randomised trial

We sought to examine the effects of daily consumption of macadamia nuts on body weight and composition, plasma lipids and glycaemic parameters in a free-living environment in overweight and obese adults at elevated cardiometabolic risk. Utilising a randomised cross-over design, thirty-five adults with abdominal obesity consumed their usual diet plus macadamia nuts (~15 % of daily calories) for 8 weeks (intervention) and their usual diet without nuts for 8 weeks (control), with a 2-week washout. Body composition was determined by bioelectrical impedance; dietary intake was assessed with 24-h dietary recalls. Consumption of macadamia nuts led to increased total fat and MUFA intake while SFA intake was unaltered. With mixed model regression analysis, no significant changes in mean weight, BMI, waist circumference, percent body fat or glycaemic parameters, and non-significant reductions in plasma total cholesterol of 2⋅1 % (-4⋅3 mg/dl; 95 % CI -14⋅8, 6⋅1) and low-density lipoprotein (LDL-C) of 4 % (-4⋅7 mg/dl; 95 % CI -14⋅3, 4⋅8) were observed. Cholesterol-lowering effects were modified by adiposity: greater lipid lowering occurred in those with overweight v. obesity, and in those with less than the median percent body fat. Daily consumption of macadamia nuts does not lead to gains in weight or body fat under free-living conditions in overweight or obese adults; non-significant cholesterol lowering occurred without altering saturated fat intake of similar magnitude to cholesterol lowering seen with other nuts. Clinical Trial Registry Number and Website: NCT03801837 https://clinicaltrials.gov/ct2/show/NCT03801837?term = macadamia + nut&draw = 2&rank = 1.

Are total omega-3 and omega-6 polyunsaturated fatty acids predictors of fatal stroke in the Adventist Health Study 2 prospective cohort?

Introduction

The effects of omega-3 (n-3) and omega-6 (n-6) polyunsaturated fatty acids (PUFA) on cerebrovascular disease remain unsettled. However, most studies have focused on marine sourced n-3 PUFA rather than total n-3 PUFA, of which the majority in the American diet is plant derived. This study therefore intended to investigate these effects in a cohort for which the vegetarian diet was more prevalent than the general public.

Methods

Cox proportional hazards with fatal stroke as the outcome was performed on the approximately 96,000 subject Adventist Health Study 2 prospective cohort. Stratification by race and sex was performed on models with a priori covariables, comparing 90^th to 10^th percentile daily intakes of energy-adjusted total n-3 PUFA, total n-6 PUFA, and the n-6 / n-3 PUFA ratio as variables of interest.

Results

For the main analytical group (78,335 subjects), the hazard ratio (95% confidence interval) for total n-3 PUFA was 0.65 (0.51–0.83), and for total n-6 PUFA was 1.37 (1.02–1.82), while adjusting for both fatty acids in the model. The n-6 / n-3 PUFA ratio was harmful with a HR of 1.40 (1.16–1.69), whereas the inclusion of total n-3 PUFA slightly attenuated the HR to 1.33(1.02–1.74). Effects were similar for the non-black sex-combined and sex-specific analyses.

Conclusion

In most analytic groups, subjects with greater total n-3 PUFA intakes have lower risk of fatal stroke, and those with a higher n-6 / n-3 PUFA ratio had higher risk. However, the n-6 / n-3 PUFA ratio remains statistically significant even after adjusting for total n-3 PUFA or total n-6 PUFA, suggesting that the ratio is of epidemiologic interest for cerebrovascular disease research.

Validity of FFQ Estimates of Total Sugars, Added Sugars, Sucrose and Fructose Compared to Repeated 24-h Recalls in Adventist Health Study-2 Participants

Sugar intake is a potentially important aspect of diet which has not previously been validated in the Adventist Health Study-2 (AHS-2). We sought to validate the food frequency questionnaire (FFQ) measurement of total sugars, added sugars, sucrose, and fructose against multiple 24-h dietary recalls (recalls) in AHS-2 participants. Food consumption data from a self-administered FFQ and six recalls from 904 participants were combined with nutrient profile data to estimate daily sugar intake. Validity was evaluated among all participants and by race. FFQ and recall means were compared and correlation coefficients (Spearman’s, energy-adjusted log-transformed Pearson’s, deattenuated Pearson’s) were calculated. Mean total energy, total sugars, and fructose intake were higher in the FFQ, whereas added sugars and sucrose were higher in recalls. The energy-adjusted (log-transformed) deattenuated correlations among all participants were: total sugars (r = 0.42, 95% CI 0.32–0.52), added sugars (r = 0.50, 95% CI 0.36–0.59), sucrose (r = 0.32, 95% CI 0.23–0.42), and fructose (r = 0.50, 95% CI 0.40–0.59). We observed moderate validity for added sugars and fructose and low-moderate validity for total sugars and sucrose measured by the AHS-2 FFQ in this population. Dietary sugar estimates from this FFQ may be useful in assessing possible associations of sugars intake with health outcomes.

Free-Living Dietary Intervention Studies: Theory-Based Protocols to Improve Subject Compliance

Objectives

Subject compliance in free-living dietary intervention studies is difficult to achieve. Published studies suggest various theoretically based strategies that can be used to improve compliance.

Methods

A weight-management dietary intervention for free-living subjects, based on a vegetarian dietary pattern, was created. Development of 7-day menus was conducted using McGraw Hills’ NutritionCalc Plus software. Menus utilized a framework from the 2015–2020 Dietary Guidelines for Americans’ Healthy Vegetarian Eating Pattern (macronutrient ratios and food group servings). A literature review was conducted to identify various counseling and technology strategies that may be effective at increasing subject compliance with their assigned study diet. The findings of the literature review was used to create study protocols. Protocol development for a food demonstration was also explored.

Results

A 1-week menu cycle for a vegetarian diet intervention was created, including a set of menus each for 1200,1800, and 2000 calories levels. The menus are inclusive of foods and portions that meet the Dietary Guidelines for Americans. Three study protocols were developed for strategies that may improve subject compliance: 1. A nutrition counseling protocol based on motivational interviewing; 2. A technology protocol on use of a dietary-self monitoring app; and 3. A food demonstration protocol highlighting vegetarian recipes. The protocols are designed to be used by study clinicians/dietitians in future intervention studies.

Conclusions

Theory-based protocols can be used to develop standardized protocols for research studies. These protocols theoretically may help to improve subject compliance.

Funding Sources

NIH BUILD PODER.

The Perceived Impact of Macadamia Nut Consumption on Feelings of Satisfaction and Bowel Function

Objectives

To assess subject perception of their level of various components of satisfaction, and changes in bowel habits, while consuming macadamia nuts during a free-living intervention study.

Methods

This was a randomized, crossover study in which free-living subjects (n = 35) were allocated to an 8 week macadamia nut (15% kcals) intervention and control (usual diet) phases. Eligibility criteria included a BMI of 25–39 kg/m,2, abdominal obesity, and presence of at least 1 other cardiometabolic risk factor. Subjects attended a biweekly clinic with the study dietitians to receive a supply of pre-weighed daily portions of nuts (mixture of raw and roasted), instructions and reinforcement on ways to incorporate the nuts into their habitual diet. A 14-item macadamia nut satisfaction questionnaire was administered at the end of the study, to assess various factors including perceptions of taste, ease of use, ease of preparation of the nut, and fullness. A 9-item bowel habits questionnaire was administered at the end of both the treatment and control phases, assessing factors including bowel frequency, perceptions of change in digestion, and stool consistency, using the Bristol Stool chart. Subject responses to the satisfaction questionnaire were calculated as proportions. Bowel movement frequency, and stool type were compared between the macadamia nut and control phases using the Wilcoxon signed rank sum test.

Results

Most subjects liked the taste (89%) of macadamia nuts, found the nuts easy to use (95%), and incorporate (95%) into their daily diet, and did not feel deprived (86%) while eating macadamia nuts. About half of the subjects felt strongly that macadamia nuts added flavor and variety to their diets, and 80% really liked including macadamia nuts into their habitual diet. In terms of bowel function, no significant difference in bowel movement frequency was noted between the macadamia and control phases. Stool consistency (Bristol stool assessment) was significantly different between the macadamia and control phases (P = 0.049).

Conclusions

Most subjects indicated favorable perceptions towards, and satisfaction with macadamia nuts. Self-reported stool consistency was different between the macadamia and control phases.

Funding Sources

Hort Innovation, Sydney, Australia.

The Association Between Phytosterol Intake and Breast Cancer Incidence in the Adventist Health Study-2 Cohort

Objectives

Breast cancer is the most diagnosed form of cancer among American women. Worldwide, it is second only to lung cancer. Phytosterols are phytochemicals found in plant foods that have potential benefits for breast cancer. Research on phytosterols and cancer associations to date has been limited to breast cancer cell lines and animal studies, and the results have been promising. Our objective is to examine the association between breast cancer incidence and phytosterol intake in the Adventist Health Study-2, a large cohort in North America.

Methods

The present study estimated the association between phytosterol intake and breast cancer incidence in 52,734 females who were part of the Adventist Health Study 2 (AHS-2) cohort. Breast cancer cases (n = 1050) were ascertained with tumor registries from 2008 to 2014. Phytosterols content in foods was quantified by using USDA 17 and other published sources. These values were used to estimate phytosterol intake from food intake assessed by a self-administered food frequency questionnaires (FFQ).

Results

Hazard ratios were below the null, but statistically non-significant for β-sitosterol [HR = 0.77, 95%CI (0.44–1.36)], campesterol [HR = 0.84, 95%CI (0.46–1.55)], stigmasterol [HR = 0.76 (0.46–1.26)], and total phytosterol [HR = 0.77, 95%CI (0.43–1.40)]. In premenopausal women, HRs ranged between 0.95–1.72; in postmenopausal women, HRs were below the null, ranging between 0.67–0.83. In both premenopausal and postmenopausal women, HRs were statistically non-significant.

Conclusions

The inverse association between phytosterol consumption and breast cancer incidence appears uncertain. The uncertainty possibly could be due to lack of power or measurement error. Additional epidemiological studies with a larger number of breast cancer cases, improved phytosterol intake estimates, or both are needed.

Funding Sources

Unilever Research &Development, Vlaardingen, The Netherlands.

Effect of Daily Macadamia Nut Consumption on Anthropometric Indices in Overweight and Obese Men and Women

Objectives

We sought to assess the effect of daily consumption of macadamia nuts as 15% of calories on body weight, BMI, waist circumference, percent body fat and skeletal muscle mass in overweight/obese men and women with elevated cardiometabolic risk.

Methods

Utilizing a randomized crossover design, we randomized 38 subjects to consume macadamia nuts daily as 15% of calories for 8 weeks (intervention) and their usual diet for 8 weeks (control), with a 2-week washout. Three subjects dropped out early; n = 35 for analysis. Subjects were healthy men and postmenopausal women with a BMI of 25–39, a waist circumference of >101.6 cm for men and >88.9 cm for women, and one additional cardiovascular risk factor (fasting plasma glucose >100 mg/dL, triglycerides ≥150 mg/dl, total cholesterol >200 mg/dL, LDL-C > 100 mg/dL, blood pressure ≥130/85 mmHg or taking anti-hypertensive medication). Macadamia nuts were provided in pre-weighed daily portions as 15% of calories calculated using the Mifflin-St. Jeor equation. Percent body fat and skeletal muscle mass (kg) were determined by bioelectrical impedance analysis. A mixed model analysis was performed with treatment, sequence, phase, and baseline values as fixed-effect terms and subjects as a random-effects term.

Results

Compared to control, consumption of macadamia nuts led to a mean weight change of –348 g (84.13 vs. 83.78 kg; P = 0.15) a mean BMI change of –0.15 kg/m2 (30.61 vs. 30.47 kg/m2; P = 0.12), and a mean waist circumference change of 0.17 cm (107.41 vs. 107.58 cm; P = 0.61). Percent body fat increased by an average of 0.26% after eating nuts (42.70 vs. 42.96%; P = 0.16). Skeletal muscle mass was slightly but significantly lower after eating nuts with a mean change of –0.237 kg (26.33 vs. 26.09 kg; P = 0.017).

Conclusions

Daily consumption of high-fat macadamia nuts for eight weeks in overweight and obese individuals did not change anthropometrics including body weight, BMI, waist circumference, and % body fat. Skeletal muscle mass was slightly lowered but likely not clinically relevant.

Funding Sources

Hort Innovation, Sydney, Australia.

Daily Macadamia Nut Intake and Its Effect on Macronutrient Intake and Nutrient Displacement in Overweight and Obese Adults

Objectives

To determine the effect of daily intake of macadamia nuts on macronutrient intake and nutrient displacement in overweight and obese adults in a randomized crossover study.

Methods

This randomized cross-over study was comprised of two phases, each lasting eight weeks. Participants (n = 35) were randomly assigned first to either the intervention (15% of calorie needs from macadamia nuts) or control (habitual diet) phase, with a two-week washout followed by the other phase. A total of six 24-hour recalls, two at baseline and two during each phase were conducted. Period adjustment t-test was used to determine the differences in macronutrient intake between the two phases. The displacement of nutrients was done by subtracting the observed intake of a particular nutrient from its’ expected intake.

Results

Compared to the control phase, there were marginal increases in the consumption of total energy (mean diff = 145 kcal), total fiber (mean diff = 2 g) and a significant increase in the consumption of total fat (mean diff = 35 g, P < 0.001). In addition, there was a significant increase in consumption of palmitoleic acid (mean diff = 5 g) and oleic acid (mean diff = 11 g, P < 0.001). However, the total saturated fat intake between the two phases was non-significant. There was a non-significant decrease in protein and carbohydrate intake. The displacement analysis revealed that participants had lower intakes of energy, protein and carbohydrates than predicted, with carbohydrates having the highest displacement of the nutrients.

Conclusions

The inclusion of macadamia nuts is associated with a marginal reduction of carbohydrate intake and an increase intake of monounsaturated fat which may have favorable health outcomes, but remains to be investigated.

Funding Sources

Hort Innovation, Sydney, Australia.

Alpha-Linolenic and Linoleic Fatty Acids in the Vegan Diet: Do They Require Dietary Reference Intake/Adequate Intake Special Consideration?

Good sources of the long-chain n-3 fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) include cold-water fish and seafood; however, vegan diets (VGNs) do not include animal-origin foods. Typically, US omnivores obtain enough dietary EPA and DHA, but unless VGNs consume algal n-3 supplements, they rely on endogenous production of long-chain fatty acids. VGN diets have several possible concerns: (1) VGNs have high intakes of linoleic acid (LA) as compared to omnivore/non-vegetarian diets. (2) High intakes of LA competitively interfere with the endogenous conversion of alpha-linolenic acid (ALA) to EPA and DHA. (3) High somatic levels of LA/low ALA indicate a decreased ALA conversion to EPA and DHA. (4) Some, not all VGNs meet the Dietary Reference Intake Adequate Intake (DRI-AI) for dietary ALA and (5) VGN diets are high in fiber, which possibly interferes with fat absorption. Consequently, health professionals and Registered Dietitians/Registered Dietitian Nutritionists working with VGNs need specific essential fatty acid diet guidelines. The purpose of this review was: (1) to suggest that VGNs have a DRI-AI Special Consideration requirement for ALA and LA based on VGN dietary and biochemical indicators of status and (2) to provide suggestions to ensure that VGNs receive adequate intakes of LA and ALA.

The Association Between Habitual Avocado Intake and Metabolic Syndrome (P08-035-19)

Objectives

To assess the relationship between habitual avocado intake, and cardiometabolic risk factors and metabolic syndrome (MetS). We hypothesized that regular avocado intake is associated with a lower occurrence of elevated blood glucose (BG), TG, blood pressure (BP), and waist circumference (WC), and/or decreased HDL-cholesterol (HDL-C).

Methods

This cross-sectional analysis was done on a random sample (n = ∼850) of subjects from the Adventist Health Study-2 cohort. Diet was assessed using a quantitative FFQ, which included an item for avocado/guacamole intake. Avocado intake (g/day) was calculated: f * s * n where f = the weighted frequency of avocado; s = the weighted portion size of avocado; and n = standard serving size (32 g) of avocado. FFQ data was also used to calculate total energy intake. Medication use, fasting BG, TG, HDL-C, BP, and WC were assessed during clinics. MetS was defined as follows: ≥3 of the diagnostic criteria defined by the Adult Treatment Panel III. Descriptive statistics including differences of means were analyzed. Logistic regression was used to determine the odds of metabolic syndrome for non-consumers (0 g/day; reference) versus consumers (>0 g/day; 51% of subjects) of avocado. Covariates were measured via a questionnaire: age, gender, race, education, energy intake, and dietary patterns.

Results

The odds for MetS for avocado consumers was non-significantly lower compared to nonconsumers: OR (95% CI) 0.87 (0.58, 1.30). Mean diastolic BP and WC were significantly lower among avocado consumers compared to nonconsumers. Mean HDL-C, TG, BG, and systolic BP did not differ between groups.

Conclusions

No relationship between habitual avocado intake and MetS has been found. However, there may be an inverse relationship between avocado intake and specific cardiometabolic risk factors: diastolic BP and WC.

Funding Sources

Hass Avocado Board, NIH, National Cancer Institute.

Avocado Intake, and Longitudinal Weight and Body Mass Index Changes in an Adult Cohort

Avocados contain nutrients and bioactive compounds that may help reduce the risk of becoming overweight/obese. We prospectively examined the effect of habitual avocado intake on changes in weight and body mass index (BMI). In the Adventist Health Study (AHS-2), a longitudinal cohort (~55,407; mean age ~56 years; U.S. and Canada), avocado intake (standard serving size 32 g/day) was assessed by a food frequency questionnaire (FFQ). Self-reported height and weight were collected at baseline. Self-reported follow-up weight was collected with follow-up questionnaires between four and 11 years after baseline. Using the generalized least squares (GLS) approach, we analyzed repeated measures of weight in relation to avocado intake. Marginal logistic regression analyses were used to calculate the odds of becoming overweight/obese, comparing low (>0 to <32 g/day) and high (≥32 g/day) avocado intake to non-consumers (reference). Avocado consumers who were normal weight at baseline, gained significantly less weight than non-consumers. The odds (OR (95% CI)) of becoming overweight/obese between baseline and follow-up was 0.93 (0.85, 1.01), and 0.85 (0.60, 1.19) for low and high avocado consumers, respectively. Habitual consumption of avocados may reduce adult weight gain, but odds of overweight/obesity are attenuated by differences in initial BMI values.