Health myths that won’t quit
AN APPLE A DAY - AN APPLE A DAY By Tyrone M. Reyes, M.D. () - December 26, 2006 - 12:00am
Myths" may be the wrong word.

It’s not that these beliefs are dead wrong. More often, they’re promising theories that are backed by too little evidence. Or they’re outdated ideas that have crumbled under the weight of recent research. In today’s column, we’ll clarify the evidence on some of these "myths" (or really, assumptions) that in fact, many people accept as truth and rarely question.
Vitamin C Prevents Colds
Ever since Linus Pauling, people have rushed for a bottle of vitamin C at the first sniffle. And some take extra C during this cold season in hopes of keeping germs at bay.

Researchers recently looked carefully at 30 trials that tested vitamin C and colds. Their conclusion: taking high doses (up to 1,000 mg – or one gram – a day) for several months didn’t ward off those pesky cold germs. However, vitamin C did appear to shorten colds slightly – by a little less than half a day per cold. On average, the vitamin reduced days of misery by about eight percent, but the results varied widely. It doesn’t hurt to try vitamin C – about 1,000 mg a day – once you feel that sore throat or reach for the tissues. Just don’t expect miracles.
Olive Is The Healthiest Oil
Fish oil is probably the healthiest, but you can’t pour it on your salad or cook with it. Olive is certainly one of the good oils. Whether it’s the best is unclear. "The data suggest that any oil that’s high in unsaturated fats – whether it’s polyunsaturated or monounsaturated – is associated with a decreased risk of cardiovascular disease," says Alice Lichtenstein of the Human Nutrition Research Center at Tufts University in Boston. "Canola is probably better than olive oil because it’s lower in saturated fat," Lichtenstein explains. What’s more, canola has more polyunsaturated fat than olive oil, "and polys lower LDL (‘bad’) cholesterol more than monos."

Our advice: At home, switch off between canola and olive oil.
Antioxidants Prevent Cancer And Heart Disease
It sounded so convincing. Damage caused by renegade oxygen could trigger cancer, injure arteries, hamper vision, and accelerate aging, said enthusiasts. And antioxidants – like beta-carotene and vitamins C and E – could neutralize the damage before it takes hold. But so far, the best studies – trials that randomly assigned people to take antioxidants or a placebo – have flopped:

• Cancer
. In two trials, high doses of beta-carotene raised the risk of lung cancer in smokers. In other studies, the antioxidants had no impact on skin, mouth, or throat cancer. And when European researchers polled the results of 14 studies on more than 170,000 people, they found that vitamins A, C, E, and beta-carotene – separately or together – failed to cut the risk of cancers of the colon, pancreas, stomach, or esophagus.

"We could not find evidence that antioxidant supplements can prevent gastrointestinal cancers," the authors concluded.

• Heart disease
. "With vitamin E and heart disease, the evidence looked rosy a few years ago," said Meir Stampfer, chairman of the department of epidemiology at the Harvard School of Public Health. Since then, researchers examined evidence from three trials testing beta-carotene supplements on 29,000 patients at high risk of cardiovascular disease. "The results of these trials have been disappointing and failed to confirm any protective effect of these vitamins for either cancer or for cardiovascular disease," wrote Robert Clarke of the Radcliffe Infirmary in Oxford, England.

That’s not to say that all antioxidants are useless. "The door isn’t closed," says Stampfer. For example, a large trial is still testing whether vitamin E and selenium can prevent prostate cancer. The mistake, he explains, is to assume that if antioxidants work, it’s because they’re antioxidants. "It’s a myth that antioxidants are a meaningful category," says Stampfer. "Some, like vitamin C, are antioxidants in one setting and pro-oxidants in others. You have to look at the specifics." If vitamin E and selenium protect the prostate, it may not be because they’re antioxidants. "They may work through different pathways," says Stampfer. "To say that a food is rich in antioxidants is meaningless."
A High-Fiber Diet Prevents Colon Cancer
"The US National Cancer Institute believes eating the right food may reduce your risk of some kinds of cancer," said the All-Bran label in 1984. "That’s why a healthy diet includes high-fiber foods like bran cereals." Within months, President Reagan underwent surgery for colon cancer. The media advised people to eat more fiber to lower their risk. But the evidence wasn’t as airtight as it sounded.

In 2000, two trials testing fiber-rich diets on precancerous colon polyps came up empty. One found no fewer polyps in roughly 1,000 people who ate a diet rich in fiber (33 grams a day) and fruits and vegetables (6-1/2 servings a day) than in 1,000 people who ate their usual diet (with about 19 grams of fiber) for four years. A second trial found no fewer polyps in 700 people who ate 14 grams a day of wheat bran fiber than in nearly 600 people who ate only two grams a day of fiber for three years.

It’s always possible that the trials didn’t last long enough, but many experts have thrown in the towel. "The theory is close to disproved," says Stampfer. But don’t throw out your All-Bran yet, he adds. "People should still eat fiber because we have strong evidence that it has other benefits." Among them: "Fiber – especially grain fiber – has been consistently linked to a lower risk of cardiovascular disease," Stampfer explains. "Researchers aren’t sure how fiber may protect the heart, but the link shows up in study after study. And there’s no question that fiber decreases the risk of constipation and diverticulitis. They’re not marquee diseases, but they make people uncomfortable and kill some."
Soy Foods Prevent Breast Cancer
Most women will do whatever they can to reduce the risk of breast cancer. Maybe that’s why they’re so willing to believe that the plant estrogens (phytoestrogens) in soy can keep the disease at bay. Yet so far, the evidence is weak.

Researchers in the Netherlands recently reviewed 13 studies that looked at soy and the risk of breast cancer. Overall, results do not show protective effects with the exception maybe for women who consume phytoestrogens at adolescence or at very high doses. What’s more, if you exclude studies that asked women who already have breast cancer what they used to eat, that leaves only four studies that asked healthy women about soy and then waited to see who got cancer. And none of them found statistically significant breast cancer reductions.

The bottom line: It’s too early to say whether soy – or other phytoestrogens – might protect the breast.
People Gain A Lot Of Weight Over The Holidays
Office parties, neighborhood gatherings, family celebrations – from Christmas to New Year – most of us are surrounded by luscious, tempting, irresistible foods. So the conventional wisdom – that most of us start the new year five pounds heavier – seems reasonable.

Reasonable but not necessarily true. In 2000, researchers tracked 200 people and found that on average, they gained only about a pound during the holidays. In the study, most people lost little weight after the holidays, whether they tried or not. And one pound is half of what the average person gains in a year. Those two pounds may not seem like much, but after 10 years, they could easily move you from trim to chubby.

Furthermore, among the overweight or obese participants in the study, 14 percent actually gained more than five pounds. Explains Susan Roberts of the Human Nutrition Research Center at Tufts University, "Weight gain is a likely consequence of overindulgence. It’s always easier to overeat than to lose weight because our bodies don’t seem to count a few thousand extra calories but start screaming hunger if we cut a few thousand."

So, have you been watching out for those Christmas calories?

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