A FEW YEARS AGO I unwittingly scheduled my annual checkup with my internist and my gynecologist within a few weeks of one another. During those two appointments I heard surprisingly contradictory advice on supplements.
At the first, with my internist, I heard about new research on calcium and vitamin D. With my blood levels, I was advised to stop taking both. Two weeks later, my gynecologist reminded me that, because of my mother’s severe osteoporosis, I should be taking the maximum doses of calcium and vitamin D.
Over the years, people learn which diet works best for them and that similar dietary advice rarely helps everyone. With low blood pressure, for example, I have learned to consume salt, especially after intense exercise in warm weather, to allay weak or shaky feelings. But that is bad advice for people with higher blood pressure.
For some, drinking a regulated amount of water – the old eight glasses a day – can be terrific for the skin and help digestion and kidney function. But for most people, the body is good at judging when it has had enough: drinking when you’re not thirsty causes the brain to switch off the swallowing reflex, and the motor cortex must work harder to swallow each sip. Over-hydrating risks debilitating weakness and even death.
Supplements are trickier, because their effects are more subtle. First, some statistics. In 2010 Americans spent $28.1 billion on dietary supplements, and 49 percent of adults used at least one supplement, according to the U.S. Preventive Services Task Force report published in 2014. The task force found no benefits in the use of multivitamins for the prevention of cardiovascular disease or cancer.
In what has come to be called The Great Vitamin Controversy, the task force also recommended “against daily supplementation with 400 IU or less of vitamin D and 1,000 mg or less of calcium for the primary prevention of fractures in…postmenopausal women.” Countering this advice, Diane L. Schneider, M.D., author of The Complete Book of Bone Health, wrote, “The news headlines are conveying the wrong message.”
Both conclusions are based on the seven-year Women’s Health Initiative study that included more than 36,000 women ages 50 to 79 and found no difference in the number of fractures between women taking supplements and those taking placebos. Dr. Schneider, however, says that on closer inspection, that the women who actually took the pills 80 percent or more of the time had a 29 percent lower rate of hip fractures. Later, the Women’s Health Initiative researchers wrote: “Long-term use of calcium and vitamin D appears to confer a reduction that may be substantial in the risk of hip fracture.”
All experts agree that it’s better to get calcium from food and vitamin D from the sun, but when those don’t fulfill the daily recommended amounts, supplements can help. In a recent article on the Smithsonian magazine website, “Five Vitamins and Supplements That are Actually Worth Taking,” vitamin D tops the list. The other four are: probiotics, zinc, niacin and garlic. Although this list is based on several studies published in the Annals of Internal Medicine, the accompanying editorial in the journal declares: “Enough is enough: stop wasting money on vitamin and mineral supplements” – because, these expert authors believe, results are not good enough to say that people NEED or even BENEFIT from any of these.
Advice on diet also remains murky, but there is increasing evidence to support tailoring advice to an individual’s genetic make-up and to their specific risks for obesity, heart disease and cancer.
Unsurprisingly, some of the variability is in our genes. In a recent study published in Nature Genetics, people with a fewer copies of the AMY1 gene, which affects the saliva’s capacity for initiating digestion of starchy foods, were at greater risk for obesity; people with fewer than four copies had an eight times higher chance of being obese than people with more than nine copies. Esoteric, yes, but proof that while some people can enjoy guilt-free pasta, others should investigate the Paleo diet.
The U.S. News & World Report’s “Best Diets 2014” ranked the high-protein diets Paleo and Dukan (named for its French creator) least successful for weight loss on a scale of five, while the DASH diet for hypertension, full of good advice like avoiding calorie- and fat-laden sweets, was number one. But subjects were not grouped in ways that could help individuals make the best dietary choices. And the DASH diet could be risky for people with low blood pressure. Also, when assessing a diet for healthiness rather than weight loss, most now agree that the Mediterranean diet is the best.
In addition, Dr. Frank Hu, professor of nutrition and epidemiology at the Harvard School of Public Health, told the New York Times that looking at individual “nutrient groups” – such as fats — in isolation could be “misleading.” Dr. Hu was responding to research showing that consumption of saturated fats might have no role in increasing heart attacks, and conversely that eating higher amounts of unsaturated fat does not lead to fewer signs of heart disease. Dr. Hu pointed out that when people cut down on fats, they tend to eat more refined carbohydrates that can also be bad for the heart. “The single macronutrient approach is outdated,” said Dr. Hu.
And what about the single-item approach for supplements – which is the content of most news reports? For example, from the same Women’s Health Initiative, an article earlier this month reported that “Calcium and vitamin D supplements after menopause can improve women’s cholesterol profiles.” But the article concludes by admitting that there is no information on whether the higher levels of calcium and vitamin D translate into lower rates of cardiovascular disease. The only certain result applies to women at risk for vitamin D deficiency – i.e., not Everywoman!
Personally, I choose a doctor and then go with their advice. In the case of my two doctors, I compromise. Every other day, I take one pill of 500 mg. calcium with 200 IU Vitamin D; on the off days, I skip these supplements entirely.
— Mary Carpenter