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Hyperlipidemia: Nutritional Considerations

Elevated concentrations of blood lipids, particularly LDL cholesterol, are a significant risk factor for atherosclerosis and coronary heart disease (see Coronary Heart Disease). Reducing saturated fat and cholesterol intake decreases these concentrations. Cholesterol is present only in foods of animal origin, and these products are often the primary source of saturated fat in a person’s diet. Thus, a diet that reduces or eliminates these products lowers total and LDL cholesterol and triglycerides.

Adding foods that prevent cholesterol manufacture in the body or that cause cholesterol to be bound and excreted in the gut also reduces serum lipids. Diet and lifestyle changes that lower triglycerides are important, because triglycerides may independently increase risk for coronary heart disease.7

The key nutritional interventions are as follows:

Reduced Dietary Fat and Cholesterol: Following a diet low in saturated fat and total fat and replacing saturated with unsaturated fat lower cholesterol production and blood lipids. The NCEP recommends Therapeutic Lifestyle Changes, which include a diet deriving ≤ 7% of calories from saturated fat and ≤ 200 mg/day of cholesterol. In outpatients, such a diet typically lowers LDL by about 5%,8 which may not be enough to achieve blood lipid goals.

More substantial diet changes appear to produce better results. Vegetarian (especially vegan) diets that are free of cholesterol and very low in saturated fat reduce LDL cholesterol by 17% to 40%, with the strongest effects seen when the diet is combined with exercise.9,10 Reducing total fat, saturated fat, and cholesterol intake also lowers triglyceride levels by approximately 20%.11

Although some authorities recommend replacing saturated fat and/or trans fatty acids with monounsaturated and polyunsaturated fats, it is important to remember that all oils are mixtures containing varying amounts of saturated fat. For example, olive oil is approximately 13% saturated fat, and fish oils range from 15% to 30% saturated fat.

For maximal lipid lowering, all fats and oils should be used sparingly, if at all. Greater fat intake leads to weight gain,12 and many patients with hyperlipidemia need to lose excess weight to prevent cardiovascular disease. Diets very low in fat are an essential component of interventions that may reverse atherosclerotic lesions.13 Consuming small amounts of fats in their naturally occurring form (eg, nuts) may be preferable to using oils because of their potentially cardioprotective nutrients: magnesium, fiber, vitamin E, and flavonoids.

Soluble fiber: Soluble fiber reduces cholesterol concentrations chiefly through binding of bile acids, leading to increased cholesterol excretion, although several other mechanisms have also been suggested.14 Soluble fiber appears to be most effective in the context of a diet low in saturated fat.14 At an intake of 8 grams per day, soluble fiber lowers total cholesterol and lowers the LDL:HDL cholesterol ratio.15 Common sources include oats, barley, legumes, and many fruits and vegetables.

While diets high in refined carbohydrates (eg, white flour) can increase plasma triglyceride concentrations, the opposite is typically seen with diets high in unrefined, low–glycemic–index carbohydrate sources, such as legumes and most whole grains.16

Soy protein reduces hepatic cholesterol synthesis and may increase the hepatic LDL receptor uptake of cholesterol. In clinical tests, soy protein decreased total cholesterol by 9%, LDL by 13%, and triglycerides by 10%.17

Nuts (almonds, peanuts, pecans, and walnuts) appear to have hypolipidemic effects, apparently due to their fiber, plant sterol, and unsaturated fat content.18 Walnuts, for example, lowered total cholesterol by 12% and LDL cholesterol by 16%, and lowered the LDL:HDL ratio by 12%.19

Plant sterols (often in the form of margarine) reduce LDL cholesterol concentrations by roughly 10% by inhibiting cholesterol absorption.20

A regimen combining the effects of a vegetarian diet, soluble fiber, soy protein, nuts, and plant sterols has been shown to lower LDL by nearly 30% in short–term clinical trials,21 an effect similar to that of statins. Although each of these foods alone contributes to lowering lipids, their effects are complementary when the foods are combined.

Avoiding alcohol may help reduce triglycerides. Alcohol appears to raise triglycerides by 5 to 10 mg/dL.6,22 Restricting its consumption joins diet, exercise, and weight loss as cornerstones of treatment for patients with elevated triglyceride levels.23

Orders

  1. Diet: Vegetarian, low–fat, nondairy, high in soluble fiber. Avoid trans fats.
  2. Nutrition consultation to advise patient in above diet and arrange follow–up.
  3. Smoking cessation.
  4. Exercise prescription (patient–specific).
  5. Alcohol restriction for hypertriglyceridemia.
  6. Change oral contraceptives to another form of contraception, as needed.

What to Tell the Family

Hyperlipidemia is a common preventable contributor to atherosclerosis. Both cholesterol and triglyceride concentrations can be reduced through restriction of saturated fat, cholesterol, transfatty acids, and total fat. Increasing dietary fiber, soy foods, and exercise can make these measures more effective. The patient’s family may also be at risk for hyperlipidemia and other cardiovascular diseases. Their adoption of the same diet and lifestyle changes being made by the patient, including smoking cessation, will encourage patient adherence and improve family members’ health.

 

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