Another study shows that supplements don’t work, may cause harm

Apr 9, 2019 by


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Getting enough nutrients from food reduces risk of death, not the same could be said for nutrients in pill form. And in fact, some supplements were linked to increased risk of death.

In 2015, only 12.2 percent of Americans met the recommendations for eating fruit, and just 9.3 percent ate enough vegetables – even though eating enough fruits and vegetables as part of an overall healthy diet reduces the risk of many chronic diseases, including cardiovascular disease, type 2 diabetes, some cancers, and obesity.

Meanwhile, 75 percent of U.S. adults take a dietary supplement of some kind, spending more than $30 billion a year on these pills and capsules that promise health.

Somewhere there seems to be a disconnect, because study after study keeps showing that supplements do not make a difference, at best, and at worst, that they can do harm. (See related stories below.)Now a new study from Tufts University says it all again with this simple conclusion: “Use of dietary supplements is not associated with mortality benefits among U.S. adults.”

The study looked at data from more than 27,000 U.S. adults, 20 years old and up, to measure the links between dietary supplement use and death from all causes, cardiovascular disease, and cancer. They analyzed whether consuming adequate or excess nutrients was associated with death and if the source of those nutrients – food versus supplements – had any effect on the associations.

They found that getting enough of certain nutrients is associated with a reduction in all-cause mortality when the nutrient source is foods, but not supplements. There was no connection between dietary supplement use and a lower risk of death.

“As potential benefits and harms of supplement use continue to be studied, some studies have found associations between excess nutrient intake and adverse outcomes, including increased risk of certain cancers,” said Fang Fang Zhang, M.D., Ph.D., associate professor at the Friedman School of Nutrition Science and Policy at Tufts University and senior and corresponding author on the study. “It is important to understand the role that the nutrient and its source might play in health outcomes, particularly if the effect might not be beneficial.”

They also discovered that too much calcium was linked to an increased risk of cancer death, which they found was associated with supplemental doses of calcium exceeding 1,000 mg/day.

Tufts summarizes the findings:

For the association between nutrient intake and the risk of death, the researchers found:

• Adequate intakes of vitamin K and magnesium were associated with a lower risk of death;
• Adequate intakes of vitamin A, vitamin K, and zinc were associated with a lower risk of death from CVD; and
• Excess intake of calcium was associated with higher risk of death from cancer.

When sources of nutrient intake (food vs. supplement) were evaluated, the researchers found:

• The lower risk of death associated with adequate nutrient intakes of vitamin K and magnesium was limited to nutrients from foods, not from supplements;
• The lower risk of death from CVD associated with adequate intakes of vitamin A, vitamin K, and zinc was limited to nutrients from foods, not from supplements; and
• Calcium intake from supplement totals of at least 1,000 mg/day was associated with increased risk of death from cancer but there was no association for calcium intake from foods.

“Our results support the idea that, while supplement use contributes to an increased level of total nutrient intake, there are beneficial associations with nutrients from foods that aren’t seen with supplements,” said Zhang. “This study also confirms the importance of identifying the nutrient source when evaluating mortality outcomes.”

While it might be easy to blame people for being lazy and wanting the convenience of a pill over the more complicated nuances of eating a well-balanced diet, I am not sure it’s that straightforward. We live in a country where convenience and fast food reign supreme. We’ve got supplement manufactures spending zillions of dollars on enticing us to believe in the magic of their miracle products. People want to be healthy, yet we’ve got a constant stream of conflicting research about what’s healthy and what’s not (although the science on supplements has been pretty consistent) – so why not double down by taking vitamins? Meanwhile, we have an access problem and a dearth of education about eating well – not helped by the culture wars incited when government officials try to nudge diets in a healthier direction.

So we here are. Eating nutritionally insipid food and trying to make up for it by taking supplements that appear to be doing more harm than good. The solution seems so easy: Eat more fruits and vegetables … alas, nothing seems very simple anymore. That said, I’m going to go eat a salad.

The research was published in the Annals of Internal Medicine.

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