There's some good and bad news about vitamins and minerals: The good news is that intake of certain vitamins and minerals is linked with a lower risk of early death. The bad news is that this link is seen only when those nutrients come from food, not supplements, according to a new study.
"Our results support the idea that... there are beneficial associations with nutrients from foods that aren't seen with supplements," seniorstudy author Dr. Fang Fang Zhang, an associate professor at the Friedman School of Nutrition Science and Policy at Tufts University in Massachusetts, said in a statement.
What's more, consuming large doses of some nutrients through supplements might be harmful — the study found that getting high levels of calcium from supplements was linked to an increased risk of death from cancer. [7 Tips for Moving Toward a More Plant-Based Diet]
The study is published Monday (April 8) in the journal Annals of Internal Medicine.
Food vs. supplements
The study analyzed information from more than 27,000 adults in the U.S. ages 20 and up who took part in a national health survey between 1999 and 2010. For the survey, interviewers asked participants about what they ate in the last 24 hours, and whether they had taken supplements in the last 30 days. Participants were then tracked for about six years, on average.
During the study period, about 3,600 people died; and of these, 945 died from heart disease and 805 died from cancer.
The study found that people who consume adequate amounts of vitamin K or magnesium had a lower risk of death from any cause during the study period, compared with those who didn't get adequate levels of these nutrients. In addition, people who consume adequate levels of vitamin A, vitamin K, zinc or copper had a lower risk of death from heart disease, compared with those who didn't get adequate levels of these nutrients.
But when the researchers considered the source of these nutrients — food vs supplements — only nutrients from food were tied to a lower risk of death from any cause or heart disease.
In addition, the study found that consuming high levels of calcium from supplements — at least 1,000 milligrams per day — was linked to a higher risk of death from cancer. But there was no link between intake of calcium from food and risk of death from cancer.
The findings suggested that "adequate nutrient intake from foods was associated with reduced mortality, [while] excess intake from supplements could be harmful," the researchers concluded.
Still, the researchers noted that they didn't objectively measure what participants consumed, but instead relied on their self reports, which may not be entirely accurate. Future studies should continue to examine the potential risks and benefits of supplements.
The risks of supplements
The new study isn't the first to link supplement use with harmful effects. In 2011, a large study found that use of vitamin E supplements was linked to an increased risk of prostate cancer in men. Also that year, a separate study among older women found that use of supplements was linked to an increased risk of death during the 20-year study period.
The Academy of Nutrition and Dietetics recommends that people try to get their nutrients from foods by eating a healthy diet that includes nutrient-dense foods. The academy points out that foods can contain beneficial components that aren't found supplements, such as fiber or bioactive compounds.
"Real food contains healthy things a pill can't give us," the academy says. "When we take a nutrient out of a food and concentrate it in a pill, it's not quite the same thing."
Still, people with certain diseases or conditions may not be able to get all the nutrients they need from food, and thus might need to take a supplement. For example, pregnant women often need to take folic acid or iron supplements to prevent birth defects and help the growing fetus. People with certain food allergies or digestive conditions may also need to take supplements.
People should speak with their doctor before taking supplements, the academy recommends.
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Originally published on Live Science.