Cholesterol is a class of lipid/fat. The body needs cholesterol to function properly. Too much cholesterol in the blood builds up in the plaque that clogs arteries and is a risk factor for heart disease. Plant foods, rich in dietary fiber, including whole grains, beans and vegetables, help to lower blood cholesterol levels.
Functions
Cholesterol is present in every cell of the body (forms cell membranes), including those of the central nervous system, muscles, skin, liver and bones. The liver manufactures cholesterol. It is also present in animal foods. In addition to maintaining cell membranes, the body uses cholesterol to make bile acids (which aid in fat digestion), sex hormones (such as estrogen and testosterone), and is used to manufacture vitamin D.
Dietary Cholesterol and Heart Disease
Though it is essential for many body functions and forms part of cell membranes, many people have blood cholesterol levels considered to be too high. High cholesterol is a risk factor for heart disease. Though genetics plays a role, dietary factors are often a contributing factor. Because we really do not need dietary cholesterol (the liver manufactures enough to meet the body's needs), fatty foods and those of animal origin should be limited. A high fiber, plant-based diet is recommended for normal cholesterol levels and optimal health.
The Fiber Factor
There are two types of fiber, soluble and insoluble. Insoluble fiber, or roughage, is found in many plant foods and helps maintain regular bowel movements. Soluble fiber is available from plant foods to a lesser degree but is extremely important. Foods rich in soluble fiber are beneficial for reducing blood cholesterol levels. Soluble fiber dissolves in the digestive tract, forming a sticky gel that acts like a protective coating. This gel traps molecules of cholesterol and prevents them from being absorbed into the bloodstream. Instead, the cholesterol passes out of the body in the stool. At least one-third of the dietary fiber you consume should be soluble fiber. The Recommended Daily Value (DV) for dietary fiber is 25 grams.
Oats, Cereals, and Grain Products
Oats (and oat bran) are beneficial for lowering cholesterol because they have the highest proportion of soluble fiber of any grain. One-cup of cooked oatmeal provides nearly 2 grams of soluble fiber. It is not just the soluble fiber in oats that make them an excellent cholesterol-lowering food. They also contain compounds called saponins, which assist fiber by binding cholesterol and carrying it out of the body.
Ready-to-eat breakfast cereals are a heart-healthy way to start the day. A 1/3-cup serving of Kellogg's Bran Buds offers 3 grams of soluble fiber, while a 1 cup serving of cooked Quaker oat bran cereal offers the same amount. Kellogg's All Bran cereal and raisin bran provide 1 gram and 1.2 grams of soluble fiber, respectively. Other grain foods that are rich in soluble fiber include pearled barley and wheat germ.
Legumes and Healthy Fats
All beans are very high in soluble fiber. Black, butter, kidney, navy and pinto beans provide the most soluble fiber (1.9 to 2.8 grams) per 1/2-cup serving. Because they are excellent vegetarian sources of protein, they can replace meat in meals (which contain artery-clogging cholesterol), making them even more beneficial.
Is it possible that a type of fat actually lowers LDL cholesterol and raises "good" high density lipoprotein (HDL) cholesterol? Yes, it is. There are two types of omega-3 fatty acids (an essential fatty acid), docosahexanoic acid (DHA) and eicosapentaenoic acid (EPA). Nuts (especially walnuts), and canola, flaxseed, soybean, walnut and wheat germ oils are all rich sources of DHA, while EPA is found in fatty, cold-water fish such as salmon, mackerel, sardines, halibut, trout and tuna. Fish oils play a role in decreasing not only LDL, but serum triglyceride (blood fat) levels.
Fruits and Vegetables
Examples of fruits that offer the most soluble fiber are: apples, avocados, dried figs, mangoes and dried prunes (1 to 2 grams per serving). Citrus fruits, such as oranges, are beneficial for lowering cholesterol in another way. They contain compounds that are powerful antioxidants. The peel and pith of citrus fruits contain flavanones (one of which is the phytonutrient compound hesperidin). Hesperidin is thought to play a role in lowering LDL cholesterol levels and raising HDL cholesterol levels.
In the vegetable family, a medium artichoke or 1/2-cup serving of broccoli, Brussels sprouts, parsnips, sweet potatoes or turnips all provide 1.2 to 2.2 grams of soluble fiber. Garlic and onions are beneficial because they contain a class of phytonutrients called Allylic sulfides. This class of phytonutrients helps raise HDL cholesterol and lower triglyceride levels. Chopping or crushing the vegetable releases the phytonutrients.
References
- Journal of Food Composition and Analysis; Individual Sugars, Soluble, and Insoluble Dietary Fiber; Betty Li, Karen Andrews and Pamela Pehrsson; May 2002
- Postgraduate Medicine; Prescription omega-3-acid ethyl esters for the treatment of very high triglycerides; R Sadovsky and P Kris-Etherton; July 2009
- Current Atherosclerosis Reports; Effects of soluble dietary fiber on low-density lipoprotein cholesterol and coronary heart disease risk; LA Bazzano; Dec 2008
