Lowering elevated blood cholesterol with dietary measures at first typically entails cutting back on or eliminating foods from your diet—notably foods that contain saturated fat and trans fats. But you can also add certain foods that have been found to have a beneficial effect on cholesterol levels.
The benefit of dietary fiber
Dietary fiber is not one substance, but several compounds with many effects in your body. Fiber is found only in plant foods and, unlike carbohydrates, protein, vitamins and minerals, is not broken down as it passes through the small intestine.
For simplicity, fiber can be divided into two broad categories: the types that are soluble in water and those that are not. Most plant foods contain both types in varying amounts, but certain foods are particularly rich in one or the other.
Both types of fiber are important, but soluble fiber is especially effective in lowering blood cholesterol levels. Soluble fiber interferes with the small bowel’s ability to reabsorb bile acids—substances that assist with the absorption of lipids. Bile acids are synthesized from cholesterol in the liver and are ordinarily reabsorbed and recycled between the liver and the small intestine. When they can’t be reabsorbed, they are excreted in the stool, and the liver has to convert more cholesterol into bile acids, reducing levels of "bad" LDL cholesterol in the bloodstream.
Where to get it—and how much. Soluble fiber is found mainly in legumes, barley, brown rice, oats and oat bran, fruits (especially apples, plums, citrus, strawberries and blueberries) and vegetables such as carrots, split peas and corn. Insoluble fiber is found primarily in wheat, especially in wheat bran, and in other whole grains.
Studies show that, on average, an increase in soluble fiber of 5 to 10 grams per day results in a five percent reduction in LDL cholesterol. Experts recommend that you try to get 20 to 30 grams or more of dietary fiber a day from a variety of foods, with at least 5 to 10 grams consisting of soluble fiber. As a general rule, try to eat foods high in both types of fiber every day.
Barley in particular is an excellent source of soluble fiber. Because of its cholesterol-lowering effects, barley can carry an Food and Drug Administration (FDA)- approved health claim that it reduces the risk of heart disease. To qualify, whole barley and dry milled barley products (such as flakes, grits and flour) must have at least 0.75 grams of soluble fiber per serving. Barley is the single best food source of beta glucan, a soluble fiber also found in oats that can lower blood cholesterol; it contains pectin, too, another soluble fiber. According to a 2010 analysis in the European Journal of Clinical Nutrition, which pooled data from 11 clinical trials, barley beta glucan (three or more grams a day) significantly decreased total and LDL cholesterol, but had no effect on HDL cholesterol. Barley may also help reduce triglycerides.
Help from supplemental fiber. It’s best to obtain your fiber from foods because you also get a variety of nutrients. But many people find it difficult to get the recommended amounts in their diet. To increase your fiber intake, you can use a product (such as Metamucil, sold as a bulk-forming laxative) that contains psyllium seed, which is high in soluble fiber. It’s well established that this grain seed helps lower total cholesterol and LDL cholesterol. A study from the Robert Wood Johnson Medical School in New Brunswick, New Jersey, found that when people taking a low-dose statin drug to lower their cholesterol added a psyllium supplement to their regimen, their LDL levels dropped an additional six percent. In fact, adding psyllium was as effective as doubling the dose of the statin.
Other ingredients in over-the-counter products that contain soluble fiber include methylcellulose (used in Citrucel and other brands), calcium polycarbophil (used in Fibercon and other brands), inulin (used in FiberChoice) and guar gum, a vegetable gum fiber that has the advantage of dissolving easily with little or no aftertaste (used in Benefiber). These products may not contain as much soluble fiber as products containing psyllium, nor have their effects on blood cholesterol levels been as well researched as the effects of psyllium products.
Adding plant stanols and sterols
Plant sterols and stanols, compounds that are structurally similar to cholesterol, mainly work by partially blocking the absorption of cholesterol from the small intestine. The compounds lower levels of LDL cholesterol but have little or no effect on "good" HDL cholesterol or triglycerides.
The amounts of stanols and sterols in plant foods aren’t sufficient to produce a benefit, but some foods have been fortified with these compounds to lower cholesterol levels. In a 2004 study published in Arteriosclerosis, Thrombosis, and Vascular Biology, daily consumption of 16 ounces of orange juice fortified with plant sterols (for a total of two grams of sterols daily) decreased total cholesterol by seven percent and LDL cholesterol by nearly 13 percent over eight weeks. Other types of food fortified with stanols or sterols, like salad dressings, cereals, and breads, are becoming available.
Current recommendations: The American Heart Association (AHA) states that adults with elevated cholesterol that has not been lowered by dietary changes (decreasing saturated fat and cholesterol intake), increased physical activity, and weight loss might consider adding two grams of plant sterols or stanols daily to their diet. Consuming more than two grams per day of plant sterols or stanols will not lower cholesterol any more effectively.