Dietary Supplements Have No Effect on Mortality in Individuals With Low Nutrient Intake

Adequate intake of certain nutrients from foods, but not dietary supplements, is associated with a reduction in all-cause mortality, shows a new study.

“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,” noted Fang Fang Zhang, M.D., Ph.D., associate professor at the Friedman School of Nutrition Science and Policy at Tufts University. “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.”

A nationally representative sample comprising data from more than 27,000 U.S. adults aged 20 and older was used to evaluate the association between dietary supplement use and death from all causes, cardiovascular disease (CVD), and cancer. The researchers assessed whether adequate or excess nutrient intake was associated with death and whether intake from food versus supplement sources had any effect on the associations.

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
  • Excess intake of calcium was associated with higher risk of death from cancer.

When sources of nutrient intake (food versus 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
  • 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.”

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