Archive 2007 2008 2009 2010

Q: Is prickly pear cactus a good food? What about its medicinal qualities? What about the juice made from it?

A: Prickly pear cactus—also known as Opuntia, nopales, nopal, or paddle cactus—is nutritious, but no powerhouse. The pads contain some potassium, plus a little calcium, iron, vitamin C, and beta carotene, as well as some other potentially beneficial compounds. In its natural state the cactus has sharp thorns, and you must wear heavy gloves to remove them. The pads you see in specialty stores have often been de-thorned. They also have hairlike spines that have to be removed. Once cleaned and trimmed, the pads are good raw in salads, stir-fried, or boiled. They taste something like green beans, and have an okra-like texture.

The cactus bears an edible fruit with a hairy skin that must be peeled. The fruit, which tastes a bit like melon or strawberries, is also made into pancake syrup and candy.

All kinds of powers are ascribed to prickly pear cactus, from curing hangovers to regulating body weight and alleviating diabetes. You can buy it in capsules or as a gel. Preliminary research suggests that substances in prickly pear may help lower blood sugar and cholesterol levels. But so far there’s no convincing evidence that the plant (or supplements made from it) is effective as a medical treatment. If you take drugs for diabetes, there’s concern that the supplements may produce unwanted interactions.

Buyer beware: Nopal juice has joined the ranks of “super juices” on the market, along with açaí and pomegranate. It comes with the predictable claims of “detoxifying” the body, protecting against inflammation and aging, and boosting immunity. A quart of the concentrate costs $25 to $50. Many common juices are also rich in antioxidants and cost a lot less.

Q: What is brewer’s yeast, and are supplements worth taking?

A: Brewer’s yeast (Saccharomyces cerevisiae) is used in beer production. It’s sold in deactivated form as a nutritional supplement (flakes or powder) supplying protein, B vitamins, and other nutrients. “Nutritional yeast” is also inactive and sold as a supplement. Neither brewer’s nor nutritional yeasts are related to Candida, the yeast that causes yeast infections.

Yeast supplements vary nutritionally, depending on the medium on which the yeast is grown (to be rich in a nutrient, yeast must grow on a medium containing it), how they’re processed, and whether they are fortified. Some are much higher in chromium or selenium, for example, and many, but not all, are rich in folic acid. Most contain little vitamin B12.

There’s no evidence that yeast supplements will reduce the risk of prostate cancer, boost energy, improve athletic skills, or have other health benefits as claimed. Chromium-rich yeast is often touted for controlling blood cholesterol and diabetes, but the evidence that chromium has such effects is mixed.

Use yeast supplements if you like the way they taste. Nutritional yeast has a nutty, cheesy flavor; brewer’s yeast tends to be more bitter—though de-bittered products are available. Compare labels for nutrients, especially if you are vegan and need supplemental B12. But a more reliable way to get supplemental nutrients is with a basic multivitamin/mineral pill.

Q: Does altitude affect blood pressure? I control my hypertension at sea level, but my blood pressure goes up at high altitudes.

A: This is nothing to worry about, as long as your blood pressure doesn’t rise too much. In healthy people as well as those with hypertension, blood pressure rises somewhat with increases in altitude. For instance, a reading of 105/65 at sea level may rise to 115/75 at 10,000 feet, dropping somewhat when the body acclimates to the altitude. But it will return to normal back at sea level. Some people have bigger increases at high altitudes.

If you have hypertension and are going above 6,000 feet, get medical advice. Your doctor will probably advise you to check your blood pressure at the higher altitude; you may need a higher dose of blood pressure medication. To help acclimate to very high altitudes, try to spend a day or two at an intermediate elevation.

Q: Can Celadrin really improve joint health as claimed?

A: It’s hard to know. Celadrin comes as a dietary supplement or a cream that you rub on the affected joint; it’s sold under different brand names. It contains chemically processed (esterified) fatty acids from bovine tallow oil that, the manufacturer claims, reduce inflammation, lubricate cell membranes, and restore cushioning fluids of the joints. One fatty acid in particular, cetyl myristoleate, has been found to have anti-arthritic properties in rats when given orally or injected. The other fatty acids and ingredients are not specified.

Only a few clinical studies have been published on Celadrin in people with osteoarthritis. In one, in the Journal of Rheumatology, those who used the cream had improvements in range of motion, walking, stair climbing, and other functions, compared to a placebo. In another study in the same journal, those who took the capsules had improved knee flexion and overall function.

But the studies were small, short-term, and potentially biased (some of the investigators had ties to the company), and they didn’t look directly at pain. Celadrin’s long-term safety is unknown.

UC Berkeley Wellness Letter, October 2010