Supplements, Nutritional Deficiencies, and the Need for Better Education

A response to the recent New York Times discussion of dietary supplements

I read with interest the recent New York Times article examining Americans’ widespread use of dietary supplements.

As a child psychiatrist for more than 30 years, I adopted the principles of nutritional medicine early in my career. In fact, many of my young patients affectionately called me the “vitamin doctor.”

That nickname reflected something very different from simply recommending vitamins. It reflected a clinical approach: asking why a patient was struggling, looking for nutritional and metabolic contributors, testing when appropriate, and treating deficiencies when they were identified.

The concern raised by the Times is real. We have become a culture accustomed to taking pills to fix problems, and supplements are increasingly recommended by influencers, podcasts, friends—and even clinicians—without adequate testing or understanding of their potential consequences.

But there is an equally important problem: medicine, and particularly psychiatry, still too often fails to identify nutritional deficiencies that may contribute to fatigue, cognition, mood, and neurological symptoms.

When Nutritional Deficiencies Matter

Two recent reports illustrate why this conversation needs more nuance.

• FOLATE: A recent report highlighting the clinical consequences of folate deficiency reminds us that fatigue may have an identifiable nutritional contributor. Folate is fundamental to one-carbon metabolism, methylation, DNA synthesis, and pathways relevant to neurotransmitter biology. The important clinical message is not that everyone needs folate. It is that deficiency can be missed if we never look for it.
• VITAMIN B12: Recent research in older adults raises another important question: are our conventional definitions of “normal” B12 always adequate for brain health? A 2025 Annals of Neurology study found that lower biologically active B12 was associated with slower processing speed, delayed visual-evoked responses, and greater white-matter hyperintensity burden—even in neurologically healthy adults whose B12 concentrations were largely within conventional ranges.

Again, the conclusion is not “take more B12.” The conclusion is that clinicians need to understand what we are measuring, recognize patients at risk for deficiency or impaired absorption, and appreciate that a laboratory reference range does not always answer the entire clinical question.

These are just two examples. The literature examining iron, vitamin D, magnesium, zinc, omega-3 fatty acids, folate, B12 and other nutritional factors relevant to brain function continues to expand.

Informed Nutritional Supplementation

This is precisely why credible education is the key—not what is found in a viral TikTok post.

Nutritional medicine is not indiscriminate supplementation. It requires knowledge of biochemistry, diet, absorption, medications, genetics, laboratory testing and, most importantly, biochemical individuality.

A patient with fatigue, anxiety, depression or cognitive symptoms should not automatically be handed a supplement. But neither should that patient spend years receiving symptom-based treatment while a significant and potentially correctable nutritional deficiency is never investigated.

We should not replace one oversimplified model with another. The answer is neither to ignore nutrition nor to assume that everyone needs the same collection of supplements.

Test when appropriate. Understand the biology. Treat identified deficiencies. Individualize care.

The scientific literature is giving us an extraordinary and rapidly growing collection of clues about nutrition and brain health. Our responsibility is to educate ourselves well enough to use those clues thoughtfully.

In health,

James Greenblatt, MD
Founder, Psychiatry Redefined