Who Should Take Supplements? Experts Weigh In

A comprehensive review published in The New England Journal of Medicine explores why supplements are essential for some people but unnecessary or harmful for others. Dr. Lindsay H. Allen of the University of California, Davis, highlights the complexity of micronutrient needs, deficiencies, and when interventions are necessary, bringing clarity to a commonly misunderstood health topic.

Micronutrient Supplements: Small But Mighty Essentials

Micronutrients—vitamins and trace minerals—are vital for health, but required in tiny amounts. Deficiencies in micronutrients like vitamin A, B12, D, iron, and zinc can cause serious diseases, including anemia, rickets, night blindness, and scurvy. Although acute deficiency symptoms are well documented, milder deficiencies without visible signs can also disrupt metabolism, gene expression, and immunity.

Who Needs Supplements? It Depends on Deficiency Risk

Key takeaway: Not everyone benefits from supplements. Routine supplementation for chronic disease prevention lacks solid evidence. Supplements should be targeted to at-risk groups, including:

• Pregnant women (iron, folic acid, calcium, vitamin D)
• Older adults (vitamin D, B6, choline)
• Vegans/vegetarians (B12, iron, zinc)
• People with limited sun exposure (vitamin D)

In low- and middle-income countries (LMICs), where vitamin A, iron, and iodine deficiencies are common, supplementation and food fortification programs have proven essential for child and maternal health.

Why Some Don’t Need Supplements—and the Risks

In high-income countries, fortified foods and diverse diets usually cover nutritional needs. Yet, oversupplementation poses risks:

• Vitamin E: Linked to increased prostate cancer risk and infections
• High-dose vitamin A: Associated with fractures
• Excess iron: Causes digestive issues and potential toxicity

Thus, indiscriminate supplementation may do more harm than good, particularly without clinical evidence of deficiency.

Challenges in Diagnosing Deficiencies

Detecting deficiencies isn’t straightforward:

• Dietary surveys can overlook absorption issues or inflammation.
• Biochemical markers (e.g., serum ferritin for iron, 25(OH)D for vitamin D) help, but interpretations vary by health status.
• Advanced tools like genomics and metabolomics are emerging for deeper insights into subtle deficiencies.

Micronutrient Interventions Worldwide: A Balanced Approach

Global impact:

• Fortification (e.g., iodine in salt, folic acid in flour) prevents widespread deficiencies.
• Targeted supplementation is used for vulnerable populations in LMICs.

However, multi-nutrient supplements, while promising, still require more evidence before becoming standard care, especially during pregnancy.

Conclusion: Personalized Supplementation is the Future

While micronutrient deficiencies remain a global health issue, universal supplementation isn’t the solution. Smarter, targeted strategies, guided by improved diagnostics and biomarkers, can ensure that those who truly need supplements receive them—avoiding overuse and unnecessary risks. Learn more nutrition insights.

More Information: Micronutrients — Assessment, Requirements, Deficiencies, and Interventions. Allen, L.H. The New England Journal of Medicine (2025). DOI: 10.1056/NEJMra2314150