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Q: Is it true that eating lots of green vegetables interferes with anti-clotting drugs such as Coumadin? My doctor told me to cut back on foods rich in vitamin K, but I read about a study calling this a myth.

A: If you are taking an anticoagulant drug, you should follow medical advice about your intake of foods rich in vitamin K, along with supplements containing it. But while it’s true that vitamin K from any source can reduce the effect of warfarin (brand name Coumadin), that does not mean you need to avoid foods rich in the vitamin. Just keep your intake of such foods relatively constant—that is, don’t eat huge servings one day, and none the next.

You should know which foods contain a lot of vitamin K. These include dark leafy greens such as kale, collards, and spinach, as well as broccoli and Brussels sprouts. If you take supplements, check the vitamin K content and ask your doctor if they are okay. Some calcium supplements contain vitamin K. Though some sources say that tea has lots of the vitamin, brewed tea actually contains none.

You may have read about a study published years ago by Dutch researchers in the journal Blood, which found that vitamin K from vegetables has little effect on anti-clotting drugs. But the study was done on healthy young people, and the conclusion was that people on anticoagulants should keep their intake of vitamin K adequate and constant. The best plan is to discuss your diet in detail with your doctor and make sure that the drug dose you are taking is producing the desired results.

Q: Can CoQ10 help treat high blood pressure?

A: The dietary supplement coenzyme Q10 (CoQ10) has been studied for its possible effects on blood pressure since the 1970s. And although we can’t yet recommend it, it looks promising.

A 2007 analysis in the Journal of Human Hypertension, which looked at 12 studies including nearly 400 people with hypertension, found that CoQ10 lowered systolic blood pressure (the top number) 11 to 17 points, and diastolic (the bottom number) by 8 points, with no serious side effects. No decreases were seen in the placebo groups.
According to the lead author, Dr. Franklin Rosenfeldt, "CoQ10 has the potential to lower blood pressure substantially either as a single agent or in combination with conventional anti-hypertensive medications . . . and may thus have a useful role in the treatment of hypertension."

Other experts are not convinced. The supplement has not been tested against standard medication, and its long-term effects and safety are still unknown. The Natural Standard, which evaluates complementary and alternative therapies, gives CoQ10 a "B" for its effect on hypertension, citing "good" scientific evidence for this use but also the need for more studies.

If your blood pressure is high, you can talk to your doctor about CoQ10—but don’t stop your regular medication. No one knows how much to take (studies have used varying amounts) or which formulation is best—and it’s expensive. And it may take several weeks to see an effect, if there is one. CoQ10 may interact with other medications, including the anticoagulant warfarin and some diabetes drugs.

By the way, while it’s known that cholesterol-lowering statins reduce CoQ10 levels in the body, there’s no evidence that this causes a rise in blood pressure—nor is taking a statin a good reason to take CoQ10. It’s not known if the supplements would even have the same blood pressure lowering effect in people who take statins.

Q: What does the term "organic" on cosmetics mean?

A: It can mean different things, or nothing at all, since the term is not regulated for cosmetics or other personal care products, such as lip balms, soaps, and lotions. Much, of course, is pure marketing hype. As shown in independent testing, "organic" cosmetics may contain the same synthetic ingredients present in conventional ones.

The USDA’s National Organic Program was not developed for personal care products, but cosmetics containing agricultural ingredients (herbs, for example) that meet its standards may be eligible to make certain organic claims and carry the green USDA seal. Few cosmetics actually meet the standards, however, because some key ingredients, such as preservatives, are not approved by the USDA for use in organic processing—and no cosmetic is likely to be 100% USDA organic.

Cosmetics may, as well, be certified organic under new standards from the nonprofit NSF International, which also sets standards for food and drinking water. Products must contain at least 70% organic content by weight, as determined by independent organic certifiers. In contrast to the USDA program, NSF allows for some chemical processing.

But more often companies simply label or describe a product as "organic" as a way to boost sales. Anything containing carbon—including petroleum-based methyl paraben found in conventional cosmetics—is, after all, technically "organic."

Bottom line: Unless accompanied by the USDA or NSF seal, organic claims on cosmetics are likely to be misleading or even bogus. Besides costing more, these products may not be any safer or more effective than other products.

Q: You once advised that aloe juice has no health benefits and warned about its unwanted laxative effects. But ads for aloe juice say the laxative has been removed and claim many health benefits. Who is right?

A: It’s true that the chemical in natural aloe that acts as a laxative is often removed by manufacturers, but that doesn’t mean that drinking aloe juice is healthful.

The claims that aloe juice has countless health benefits—good for everything from hair loss and fatigue to cancer, bad breath, and weight loss—are not backed up by scientific research and are advanced only by marketers. Recent studies have looked at the juice as a preventive for kidney stones and as a treatment for irritable bowel syndrome and inflammatory bowel disease, but the evidence is not convincing. Even if it did do some good, you can’t tell how much aloe is really in these juices.

On the other hand, there are reports of liver and kidney damage (including kidney failure and death), abdominal pain, and reduced potassium levels from aloe consumption. Aloe can also interact with anti-clotting drugs. Pregnant and breastfeeding women, as well as children, should avoid aloe juice.

UC Berkeley Wellness Letter, January 2010