The New Low-Cholesterol Diet: Soy Protein

Last Editorial Review: 9/30/2005

Versatile soy protein may lower bad fats floating in your bloodstream

By R. Morgan Griffin
WebMD Weight Loss Clinic - Feature

Reviewed By Cynthia Haines, MD

Soy protein can be a meal, a side dish, a snack or a drink. Made from the soybean, it's a staple of Asian diets. Yet it's largely been the butt of jokes about hippies and vegans - until recently. Today, research shows that if you are a man - or a woman - with rising cholesterol, it's time to take soy more seriously.

How Does Soy Protein Help?

A number of studies show that soy protein may lower "bad" LDL cholesterol and triglycerides without lowering "good" HDL cholesterol. Researchers aren't exactly sure how soy protein does this. It may be a combination of the effect of the protein and natural chemicals in soy called isoflavones.

What's the Evidence?

There have been many studies of the effects of soy on cholesterol. One major 1995 article published in the New England Journal of Medicine found that replacing animal protein with soy protein could lower levels of total cholesterol, bad LDL cholesterol, and triglycerides. At the same time, it didn't significantly lower levels of "good" HDL cholesterol.

Some recent studies have shown that soy protein, when eaten along with other cholesterol-lowering foods, can have a big effect. In a study published in the American Journal of Clinical Nutrition in 2005, researchers tested cholesterol-lowering drugs against cholesterol-lowering foods in a group of 34 adults with high cholesterol. People ate 50 grams of soy protein daily along with other cholesterol-lowering foods. The results were striking: the diet lowered cholesterol levels about as well as cholesterol drugs.

However, not all studies agree. A 2005 analysis of various studies led by the U.S. Agency for Healthcare Research and Quality found that soy had a modest effect on cholesterol levels. Researchers found that eating a high amount of soy -- equal to about a pound of tofu a day -- only added up to a 3% reduction in "bad" cholesterol levels.

Nonetheless, the FDA felt that the benefits of soy were clear enough to grant it the status of a "health claim" in 1999. This means that food manufacturers can advertise the heart-healthy benefits on soy products.

Getting Soy Into Your Diet

There are almost endless ways of getting soy into your meal plan. Here's a rundown of some of your options.

  • Tofu is a solid extract of soybeans. "It has a mild, bean-like flavor," says Ruth Frechman, RD, a spokeswoman for the American Dietetic Association (ADA.) "It can be added to anything you cook or it can be eaten right out of the package." Tofu is often used in stir-fries, curries or stews. It tends to pick up the flavor of the sauce it's in.
  • Soy nuts are roasted soybeans, which can make tasty snack. "Soy nuts are a convenient, crunchy source of protein," Frechman tells WebMD.
  • Soymilk is made from ground soybeans mixed with water. You can substitute soymilk for milk in your coffee or your cereal. Or you can just drink it on its own. "A lot of my clients really like smoothies made with soy milk," says ADA spokeswoman Suzanne Farrell, MS, RD. "That's a great way to get soy into your diet."
  • Soy burgers, soy cheese, and other products now fill the freezers and refrigerators at your local supermarket. Manufacturers have come up with soy products that mimic just about every kind of meat and dairy product. Buy a few different types and give them a try.
  • Edamame are soybeans still in the pod. They're sold either frozen or fresh. Frechman recommends microwaving frozen edamame in a little water and chicken bouillon for an easy way to get soy protein.
  • Tempeh is a fermented soybean cake. It can be used as a meat substitute, and works well in spaghetti sauce.
  • Miso is a paste made from soybeans that is used for soup stocks or as a seasoning.
  • Soy flour is a powder made from ground, roasted soybeans. It can be added to baked goods.

Choose the foods that you like. The key is to substitute soy for some meat protein products, especially those that have saturated fat.

How Much Do You Need?

The FDA recommends eating 25 grams of soy protein a day. This amount may lower "bad" cholesterol levels by as much as 10%. Some experts recommend higher levels of up to 50 grams each day.

However, 50 grams is a lot of soy protein. Eating that much every day will take some careful planning and dedication. Start out slowly. Gradually increase the amount of soy in your diet as you figure out the types that you like.

Low-Cholesterol Diet Includes:

SOURCES: Suzanne Farrell, MS, RD, spokeswoman, American Dietetic Association. Ruth Frechman, RD, Los Angeles; spokeswoman, American Dietetic Association. Keecha Harris, DrPH, RD, spokeswoman, American Dietetic Association. FDA web site. American Dietetic Association web site. National Heart, Lung, and Blood Institute web site. American Heart Association web site. Jenkins, D. American Journal of Clinical Nutrition, February 2005; vol 81:pp 380-87. Jenkins, D. Journal of the American Medical Association, July 23-30, 2003; vol 290: pp 502-510.

©2005 WebMD Inc. All rights reserved.


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