BACKGROUND AND PURPOSE:

• Although the majority of the US population use dietary supplements, data remains limited as to benefits vs risks
• Chen et al. (Annals of Internal Medicine, 2019) evaluated dietary supplements, nutrient intake and mortality.

METHODS:

• Prospective cohort study
• Data sets
  • NHANES (National Health and Nutrition Examination Survey)
  • National Death Index mortality data
• Participants
  • U.S. adults ≥20 years
• Measurements
  • Dietary supplement use in the past 30 days (in-house interview with follow up questions for specifics)
  • Nutrient intake from food and supplements (24-hour diet recalls conducted by trained interviewers)
• Definitions
  • Inadequate nutrient intake: Levels of total nutrient intake (foods plus supplements) below the Estimated Average Requirement or Adequate Intake level specified in the Dietary Reference Intakes
  • Excess nutrient intake: Levels above the Tolerable Upper Intake Level
• Primary outcomes
  • Mortality (all causes)
  • Cardiovascular disease (CVD)
  • Cancer
• Data also collected on demographics, lifestyle factors and comorbid conditions to adjust for confounding

RESULTS:

• 30,899 U.S. adults were included
  • Median follow up: 6.1 years
• Ever using dietary supplements did not impact mortality
• Reduced all-cause or CVD mortality was associated with adequate intake of
  • Vitamin A | Vitamin K | Magnesium | Zinc | Copper
  • Associations restricted to nutrient intake from food
• Increased risk of cancer death was associated with excess intake of calcium
  • Multivariable-adjusted rate difference: 1.7 (95% CI, −0.1 to 3.5) deaths per 1000 person-years
  • Related to calcium intake from supplements rather than food
    • Comparing ≥1000 mg/day vs no use
    • Multivariable-adjusted rate difference: 1.5 (95% CI, −0.1 to 3.1) deaths per 1000 person-years

CONCLUSION:

• Use of dietary supplements are not associated with decreased mortality when adjusted for education and lifestyle factors
• Adequate diet from food is associated with reduced mortality
• Excess supplement may be associated with increased mortality
• Authors recognize limitations, including
  • Observational studies cannot account and related confounding
  • Self-reporting recall bias

Learn More – Primary Sources:

Association Among Dietary Supplement Use, Nutrient Intake, and Mortality Among U.S. Adults: A Cohort Study

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Results from the VITAL Trial: Does Vitamin D Reduce Cardiovascular and Cancer Risk in the General Population?