Nutritional Management of Dyslipidemia
Nutrition is an important treatment for dyslipidemia, CHD risk factors and for the prevention and treatment of CVD. Numerous epidemiological studies and prospective clinical trials including the Framingham Heart Study,[191,192] Seven Countries Study,[193,194] Pritikin diet studies,[195–197] Ornish Lifestyle Heart Trial,[198–201] Omni Heart Trial, Portfolio diet,[202–205] Mediterranean diet,[206–210] Lyon Diet Heart Study, Indian Heart Study, Predimed study[210–213] and Paleolithic diet have clearly established the relationship between diet, serum lipids, inflammation and CVDs including coronary heart disease and stroke.
Three cohorts of the Framingham Heart Study with over 10,000 subjects have demonstrated improved CV risk on lipid-lowering diets that decrease total and LDL cholesterol, TG and increase HDL.[191,192] The Seven Countries Study was an international study that investigated lifestyle and diet.[193,194] A high fat diet increased prevalence of CVD. The Pritikin Principle Diet, which included low-fat diet (10% of total calories) with primarily vegetables, grains, and fruits, combined with exercise, improved the lipid profile.[195–197]
Ornish et al. evaluated an intensive therapeutic approach that combined a low fat (10% total calories, low cholesterol of 10 mg per day, complex carbohydrate, low refined carbohydrate vegetarian diet, exercise, and other lifestyle changes such as stress reduction, smoking cessation and group psychosocial support.[198–201] The experimental group compared with the control group had statistically significant reductions in LDL-C, frequency of angina episodes, and regression in coronary artery stenosis at years 1 and 5. The Optimal Macronutrient Intake for Heart Health Trial (Omni Heart Trial) was a randomized controlled intervention crossover study of 164 adults using a Mediterranean-style diet to evaluate plasma lipids and blood pressure. Three diets were included a carbohydrate-rich diet, a protein-rich diet with 50% from plant sources, and a diet rich in monounsaturated fat. The monounsaturated fat-rich diet increased HDL-C levels, lowered TG, with no change in LDL-C. The protein-rich diet decreased LDL-C, TG and HDL-C compared with the carbohydrate diet. Substitution of the carbohydrates with either proteins or monounsaturated fat lowered blood pressure, improved serum lipid levels and reduced cardiovascular risk.
The Portfolio Diet Study was a randomized control trial of 14 dyslipidemic subjects given a vegetarian diet, with additional soluble fiber, nuts, soy protein and plant sterols. At 4 weeks the LDL-C fell 29.6% and TG fell 9.3% in the diet group versus 8.5% in the control group. There was a 33.3% decrease in LDL C and 11% decrease in TG in those given a statin drug. In a follow-up study of the portfolio diet in 66 dyslipidemic adults for 1 year, 31 participants had reductions in LDL-C >20% related to compliance with the diet. The most recent Portfolio diet of 351 subjects showed an LDL-C reduction of 13.8 vs 3% in the control group.[204,205] Increasing the monounsaturated fat content increased serum HDL-C levels but maintained the reduction in LDL-C.[204,205]
The Mediterranean-style diet consists of a high intake of vegetables and fruits, bread and other cereal grains, potatoes, legumes, nuts, seeds, monounsaturated fat as olive products (15–20% of total calories), animal products (meat, poultry, fish, dairy and eggs) at a low-to-moderate level and red wine. The Lyon Diet Heart Study was the first randomized single-blind secondary prevention trial 600 participants over 4 years with a prior myocardial infarction (MI) to investigate the effect of a Mediterranean-style diet on CVD.[207–209] The primary outcome measurement of fatal or nonfatal MI was significantly reduced. For example, the total fat in the experimental diet was 30.5% fat but only 12.5% MUFA and was enriched in α-linolenic acid, an omega-3 polyunsaturated fat. The recent 4.8 year study of 7447 subjects given the Mediterranean diet in primary prevention of CVD found a 28–30% reduction in major CV events in those on the MD with extra-virgin olive oil or nuts. The Indian Heart Study was a 1-year evaluation of a Mediterranean-style diet enriched in α-linolenic acid administered to the treated group, while the control group was advised on smoking cessation, stress management, regular exercise, reduction of dietary fat and alcohol. Compared with the control group, the treated group had a 38% reduction in nonfatal MI and a 32% reduction in fatal MI.
PREDIMED[210,212] was a 3-month randomized cross-sectional study of 772 asymptomatic Spanish adults at high risk for cardiovascular disease treated with one of three diets. A control group and two experimental arms that used a Mediterranean-style diets, differing only in the primary fat source: EVOO at 1 l per week or mixed nuts at 30 g per day. The treated groups showed a reduction in the total cholesterol:HDL-C ratio, at -0.38 (95% CI: -0.55 to -0.22) for those on the Mediterranean/EVOO diet and of -0.26 (95% CI: -0.42 to -0.10) for those on the Mediterranean/nuts diet. In addition, four inflammatory markers were significantly reduced in the EVOO group including HS-CRP, IL-6, ICAM-1 and VCAM-1. All but the HSCRP were reduced in the nut consumption group.[210–217]
The hunter-gatherer diet, or Paleolithic diet,[214–217] is considered to be close to Man's ancestral diet and consisted of a diet high in foliage, leafy vegetables, fruits, seeds, nuts, plant sterols, vegetable protein, fiber and omega-3 fatty acids and lean animal protein, which improves lipids and CVD risk.
Summary of Nutrition, Dyslipidemia & CVD
Although many questions still exist regarding the optimal intake of fats, which types of fats, types and quality of protein, as well as the dietary intake of complex and refined carbohydrates, most studies clearly indicate that trans fatty acids and refined carbohydrates have an adverse effect on serum lipids and cardiovascular outcomes. Some saturated fats may be adverse, others neutral and some potentially beneficial. The MUFA and omega 3 fatty acids are consistently beneficial for dyslipidemia and CVD. The vegetarian diet with increased complex carbohydrates and fiber with lower dietary cholesterol is also beneficial. Protein intake of lean, wild and organic types of protein and cold water fish improves lipids and CHD risk factors.
Clin Lipidology. 2014;9(3):333-354. © 2014 Future Medicine Ltd.