Archive 2006 2007 2008 2009

Q: I read that a type of blood cholesterol called Lp(a) increases the risk of heart attacks. Should I have it measured?  

A: In June a Danish study in the Journal of the American Medical Association provided the strongest evidence so far that a high level of Lp(a) is an independent risk factor for heart attacks. It’s too soon, however, to recommend routine Lp(a) testing, according to Dr. Ronald Krauss, a member of our Editorial Board and co-author of the 2009 Wellness Report Controlling Your Cholesterol.

Short for lipoprotein(a), Lp(a) is one of several cholesterol-related compounds in the blood that can be measured in specialized lab tests to get a more nuanced idea of coronary risk—beyond the routine tests for LDL (“bad”) and HDL (“good”) cholesterol. But there’s much debate about which, if any, of these additional factors are most important, and for whom.

Lp(a) is similar to LDL cholesterol, except that it carries a protein on its surface called apo(a), which resembles another protein, plasminogen. Plasminogen aids in the breakdown of blood clots. It’s theorized that Lp(a) interferes with plasminogen and thus the normal dissolving of blood clots. In addition, like LDL cholesterol, Lp(a) contributes to plaque formation in arteries.

Levels of Lp(a) are strongly determined by genetics and are difficult to lower, except by prescription-strength niacin. Statin drugs do not reduce it. Most important, it’s not known whether lowering Lp(a) actually reduces coronary risk—the Danish study didn’t look at this. Still, your doctor may want to do the test if you are at moderate or high risk for heart disease and have certain risk factors, especially a family history of premature heart disease.  

Q: Is the oil from New Zealand green-lipped mussels better than the fish oil in other capsules? Is it a good treatment for arthritis?

A: There’s no reason to believe that the oil from any particular shellfish or finfish is superior to the others. The omega-3 fats in seafood are recommended to help prevent heart attacks and strokes, and there is some evidence they can reduce the inflammation of rheumatoid arthritis and other inflammatory conditions. By far the best food source of omega-3s is seafood, but for those who rarely eat fish, supplements are an option.

Supplements made from the oil of the New Zealand green-lipped mussel (Perna canaliculus) are sold under brand names such as Moxxor, Lyprinol, and Seatone. It’s a lucrative and competitive market, with lots of claims and testimonials. Green-lipped mussel oil has been studied scientifically. Like all marine oil supplements, it has anti-inflammatory properties, and some lab and animal studies suggest it may be as effective as aspirin and similar drugs.

But outside the lab, research on green-lipped mussel oil as a treatment for osteoarthritis or rheumatoid arthritis has produced mixed results. The Natural Standard, a scientific group that evaluates supplement claims, gives green-lipped mussel oil poor grades as a treatment for osteoarthritis, and says the evidence does not support its use for rheumatoid arthritis. Many other claims are made for the oil—everything from preventing soreness after exercise to warding off cancer—but there’s no basis for any of this.

This is probably the most expensive omega-3 supplement you can buy, and no better than the others. For more on fish oil supplements, see our Special Report.

Q: Can inulin boost calcium absorption, as some yogurts claim?

A: Inulin is a fiber-like substance in many fruits and vegetables. Usually extracted from chicory root, it’s used in yogurt, salad dressings, frozen desserts, and other foods to replace sugar and fat and improve texture. In recent years manufacturers have begun promoting inulin for its supposed ability to improve intestinal health and absorption of nutrients, particularly calcium.

Though research in people is limited and results mixed, there is some evidence that inulin can boost calcium absorption. For example, a study this year from Germany found that postmenopausal women who consumed inulin for two weeks had an increase in calcium absorption and a decrease in bone breakdown. And in a study in the American Journal of Clinical Nutrition in 2005, children who consumed inulin for a year showed increases in calcium absorption and bone mineral density.

But more research is needed to see how much extra calcium is actually deposited in bones. Not everyone responds to inulin, possibly because of genetics. And yogurts may not contain an effective dose. At the very least, inulin is a source of soluble fiber, though large amounts may cause flatulence.

Bottom line: Low-fat or nonfat yogurt—with or without inulin—is good food. Even if inulin does aid calcium absorption a little, most people don’t get enough calcium to begin with. Adults up to age 50 should aim for 1,000 milligrams of calcium a day from food and/or supplements; older people, 1,200 milligrams a day.

Q: What is whole white wheat flour? I thought whole wheat was always darker.

A: Most American wheat is hard red spring wheat, but about 15% now is hard white wheat, which is a sort of albino wheat. Whole white wheat looks like refined wheat (which has had the bran and germ removed), but in fact it contains the whole grain.

Hard white wheat is not new—Australia and China grow lots of it. It has all the fiber, vitamins, and minerals of regular whole wheat, but is slightly different in chemical composition and has a milder taste.

If you’re buying bread or crackers, check the ingredients. “Whole wheat” is the best choice, whether it is whole white wheat or regular whole wheat. It should be 100% whole wheat, or else whole wheat mixed with other whole grains, such as oats. Don’t be confused by “enriched wheat flour,” which is always refined wheat.

UC Berkeley Wellness Letter, September 2009