Functional Component Diet Study Review
By Dr. Karl Nadolsky
An appealing study evaluating “functional components” of diet was recently undertaken and published in the journal Nutrition & Metabolism looking at the changes in cardiometabolic risk factors focusing on a combination of low glycemic foods, antioxidant-rich foods, oily fish with high omega-3 fatty acids, high soluble fiber foods, soybean/whole barley kernel foods, almonds, stanols, pre-biotics, and a probiotic (Lactobacillus plantarum). I thought this was intriguing as our basic philosophical and evidence-based dietary recommendations have arisen over time from evaluating dietary studies and actually include these “functional components” within our guidelines. We often feel frustrated with many studies performed which seem to deviate towards only evaluating straight macronutrient content or just one aspect of what is a potentially healthful addition to one’s general diet.
This study evaluated 36 females and 8 males with average age 63 (50-73) years and average BMI of 28 (25-33) but who were all presumably “healthy.” The only medications allowed for inclusion were thyroid replacement (1 female) and anti-inflammatory pain meds. Patients were also instructed to stop any supplements 2 weeks prior to the beginning of the trial. Baseline cardiometabolic parameters of note were as follows: total cholesterol 222mmol/L, HDL 59, non-HDL 163, LDL 141, triglycerides 117, A1c 5%, CRP 2.58mg/L, systolic blood pressure 139 mmHg, and diastolic blood pressure 80. The trial was a randomized, controlled, crossover design where patients were randomly assigned to either the “active” diet or the control diet with each phase lasting 4 weeks followed by a 4 week washout period (baseline patient diet) before crossing over to the other diet trial. The participants were asked to maintain their baseline physical activity and exercise of which about half exercised an hour daily, a third exercised 30-60min daily, and 22% reported <30min exercise daily. Other than almonds and fish, the “active” foods were provided. Compliance was enforced via 2-wk rotating menu plan, recipes, and checks/balances.
Both diets had similar calories with the control diet providing 2045kcal/day for women and 2570kcal/day for the men while the “active” diet averaged 2100kcal for women and 2615kcal for men. Macronutrient percent averages for the control and “active” diets were as follows: protein 15% and 19% respectively, carbohydrates 56% and 51% respectively (fiber g/day 22-26/49-61 for women-men resp), and fat 29% and 31% respectively (sat 13%/6%, mono 11%/13%, ω-6 3%/4%, ω-3 0.8%/2.2% resp). Most notably I thought important that protein increased slightly, carbohydrates decreased slightly but more importantly fiber increased, and the fatty acid profiles improved with a higher percent coming from mono-unsaturated and omega-3 poly-unsaturated fatty acids (omega-6 also increased to a lesser extent with a significant decrease in percent from saturated fatty acids). See the original study for more specifics on food items but examples of additions to the “active” diet included: soybeans/soy protein, viscous fibers, β-glucans, guar gum, omega-3 rich fish, almonds, plant stanols, cinnamon, blueberries, vinegar, the probiotic, and whey protein. None of the added ingredients to the “active” diet were included in the control, save for trivial amounts of omega-3 fatty acids. Compliance was reported to be good and similar, approximately 90% for each diet.
The goal of the study was to evaluate cardiometabolic alterations, but as suspected by most, the “active” diet was reportedly more satiating than habitual diets (50% vs 25% resp) and there was also a small but significant weight loss greater with the “active” diet vs the control diet (-0.9% vs -1.8% resp). Lipid numbers improved with the “active” diet with reductions in total cholesterol, LDL, and triglycerides by 26%, 24%, and 19% without any change in the control group while HDL actually marginally decreased by similar amounts in both groups (“active” group had improved LDL/HDL ratio and Apo B). Though fasting blood glucose was slightly higher after “active” diet, neither were significantly different and the HbA1c decreased slightly after the “active” diet. Blood pressure was slightly improved in the control diet (SBP -3mmHg, DBP -3mmHg) while the active diet showed slightly better blood pressure lowering (-8mmHg and -3mmHg resp). For inflammatory markers, the CRP decreased significantly with the “active” diet at -29% while the control diet showed a 12% increase.
With all those differences in improvement or worsening of cardiometabolic parameters, Reynolds scores and Framingham scores were calculated for any change in 10 year predicted cardiovascular risk. The control diet showed a slight increase of those scores at 1% and 4% respectively while the “active” diet resulted in -35% and -30% decreases in risk at least conferring a calculated prediction of cardiovascular disease with the “active” diet.
So what does this study show us that we want as a take away message? It seems to at least continue confirming our recommendations which have previously formed out of individual component studies and other epidemiological studies regarding a quality diet, more importantly than decreasing quantity, and some of the specific parts of that quality all mixed together. Also note that the calories in the “active” diet averaged more than the control. It gives more credence to our suggestions of eating high fiber and nutrient dense vegetables instead of processed starches, almonds and likely other nuts instead of processed snack foods, berries instead of juice or other “candied” form of fruit, and getting more fat from fish and plant sources. It also supports the use of other dietary optimization tools like low-calorie, high-fiber protein shakes, probiotics, and cinnamon, etc. Long story short, study the dietary recommendations we give, and continue to evaluate results of studies like these to validate or perhaps even change some of your dietary practices to optimize your health, live lean, live long, and prosper!
Nutr Metab. 2012;9(29)