Supplements: The Good, The Bad and The Ugly

ISSUE 0.4

Why your body might need them, when they actually help, and when they may be doing more harm than good

Dr. Oluwakemi Olowoyo, MD

Walk into almost any pharmacy, grocery store, or health food store, and you will find shelves filled with promises.

More energy. Better sleep. Stronger immunity. Improved memory. Better metabolism. Healthier aging.

There seems to be a supplement for almost everything. And Americans are buying them — nationally representative CDC data show that approximately 60% of American adults use at least one dietary supplement, with use exceeding 80% among women 60 and older.

Clearly, supplementation has become part of everyday life.

But perhaps we have been starting with the wrong question.

Instead of beginning with "What supplements should I be taking?" — what if we started with "Why would my body need supplementation in the first place?" And perhaps an even more important question: "Is something preventing my body from obtaining, processing, or using what it needs?"

These questions take us somewhere much more interesting than the vitamin aisle. They take us into how the human body actually works.

The Right Tool, for the Right Person, for the Right Reason, at the Right Dose, at the Right Time, for the Right Amount of Time.

Why Would Your Body Need Supplements in the First Place?

Your body requires a continuous supply of nutrients to function. Some of these are called essential nutrients because your body either cannot make them at all or cannot make enough to meet its physiological needs — they have to come from outside the body, primarily through food.

But essential does not mean more is better. Vitamin C is essential. Iron is essential. Vitamin B6 is essential. Yet excessive amounts can be unnecessary and, in some cases, harmful.

Eating a nutrient is only the beginning. Your body must be able to:

Digest it → Absorb it → Transport it → Convert or activate it when necessary → Get it into the appropriate tissues → Use it → Store or eliminate it appropriately.

A disruption anywhere along that pathway can affect nutritional status. Here are seven reasons that happens.

1Sometimes We Simply Aren't Getting Enough

Our bodies cannot manufacture every nutrient they require. If our intake is inadequate, deficiencies can develop. But inadequate nutrition doesn't necessarily mean starvation — or even insufficient calories.

You can be overfed and still be undernourished. Highly processed, energy-dense foods can provide plenty of calories while contributing relatively little of some essential nutrients. And every time one food occupies space in our diet, another food doesn't — regularly filling our diets with nutrient-poor foods can displace opportunities for nutrient-dense foods.

There is another problem I increasingly encounter in clinical practice: limited dietary variety. Some people eat essentially the same small collection of foods day after day. Those foods may not necessarily be unhealthy — but even healthy foods don't contain everything. Food insecurity, restrictive eating patterns, reduced appetite, cultural or personal food preferences, and medical conditions can further contribute.

Nutritional adequacy is therefore not simply about eating enough. It is about eating enough of what the body actually needs.

2Sometimes We Eat the Nutrients but Cannot Digest or Absorb Them Properly

Imagine eating a beautifully balanced meal — protein, healthy fats, fiber, vitamins, minerals, beneficial plant compounds. But what happens if your digestive system cannot adequately process or absorb them? The nutritional content of the meal is only half the story.

Stomach acid, digestive enzymes, bile, the intestinal lining, and specialized transport systems all help convert food into nutrients the body can actually use. Certain conditions interfere with these processes: pernicious anemia can impair vitamin B12 absorption; celiac disease can damage the small intestine and impair absorption of iron; exocrine pancreatic insufficiency can impair absorption of the fat-soluble vitamins A, D, E, and K; bariatric surgery often creates a need for lifelong nutritional supplementation and monitoring.

You can eat a nutrient without necessarily absorbing enough of it.

3Sometimes the Nutrient Is There but the Body Has Trouble Using It

After absorption, nutrients must travel through the bloodstream, reach the appropriate tissues, and participate in cellular reactions. And nutrients rarely work alone.

Imagine being told you have anemia. Your first thought might be "I need iron." And sometimes that is exactly what you need. But not all anemia is iron-deficiency anemia — many people know that B12 or folate deficiency can also cause anemia. But did you know your body also needs copper to handle iron properly? I have encountered patients who load up on zinc every cold-and-flu season, not realizing that excessive zinc supplementation over time can interfere with copper absorption. One nutrient intended to help can inadvertently create a problem with another.

Anemia is a finding. It is not the diagnosis.

Nutrients don't work alone. They work within systems.

Vitamin D helps regulate calcium absorption and mineral metabolism. Magnesium participates in the reactions involved in vitamin D metabolism. This doesn't mean everyone needs to take vitamin D, and it doesn't mean everyone taking vitamin D needs a magnesium supplement — it means adequate magnesium intake matters. Legumes, nuts, seeds, whole grains, and leafy greens all contribute meaningful amounts. Sometimes the most appropriate "supplement strategy" begins in the grocery store.

4Sometimes Our Requirements Increase

There are periods when ordinary nutrient intake may no longer be sufficient. Pregnancy is an obvious example — adequate folate status is essential before and during early pregnancy, and folic acid supplementation has been demonstrated to reduce neural-tube-defect risk. Growth, lactation, certain illnesses, recovery, and aging can also alter nutritional requirements.

But aging itself does not automatically mean everyone needs an extensive supplement regimen. The goal is to identify the particular need, if one exists, and strategically work to meet it through dietary modification whenever possible and supplementation when necessary.

5Sometimes We Are Losing Nutrients Faster Than We Replace Them

A person may consume adequate nutrients and still experience ongoing losses. Consider iron deficiency caused by gastrointestinal bleeding — iron supplementation may replenish depleted stores, but if the bleeding continues, the underlying problem remains.

Think about discovering water spreading across your kitchen floor. You need to mop up the water. But you also need to turn off the faucet. Sometimes both have to happen simultaneously.

Replacing what has been lost may be necessary. Finding out why it keeps being lost can be equally important.

6Sometimes Medications Change Nutrient Requirements

Medications can improve health and save lives — but they can also affect biological pathways beyond their intended targets. Long-term metformin use can increase the risk of vitamin B12 deficiency. Acid-suppressing medications can interfere with absorption of food-bound B12, and prolonged proton-pump-inhibitor use has also been associated with low magnesium in some individuals. Certain diuretics alter electrolyte handling.

This does not mean everyone taking these medications needs supplements. It means medication history belongs in the nutritional assessment.

7Sometimes Genetics Matter

Our genes help determine how we make enzymes, transport molecules, and regulate biochemical pathways — this is the field of nutrigenomics, an area I believe will continue to expand our understanding of individualized nutrition. But genetics needs context.

The MTHFR gene produces an enzyme involved in folate metabolism, and a common variant can substantially reduce its activity. 5-methyltetrahydrofolate (5-MTHF) can produce strong folate biomarker responses in people with altered folate metabolism — biologically interesting. But we need to distinguish biochemical plausibility from demonstrated clinical superiority: people with common MTHFR variants can still process folic acid, and folic acid remains the supplemental form directly demonstrated to prevent neural tube defects. We do not currently have evidence that replacing folic acid with 5-MTHF prevents more neural tube defects in people with the TT genotype.

That doesn't mean genetics is irrelevant — quite the opposite. It means genetics provides another piece of information to interpret alongside diet, labs, symptoms, medications, history, and clinical evidence. Sometimes genetics changes the entire treatment. We'll come back to that shortly.

THE GOOD — When Supplements Really Can Help

Sometimes a supplement replaces something the body lacks. Other times, we deliberately use a nutrient or compound to influence physiology. These are different applications.

THE BAD — When More Is Not Better

If a nutrient is essential, taking more must be better. Right? No. Human physiology depends on balance. Too little iron causes anemia; too much promotes oxidative injury. Zinc is essential, but excessive supplementation impairs copper absorption. Vitamin B6 is essential, yet excessive supplemental B6 can cause peripheral neuropathy.

And sometimes the problem isn't one obviously excessive supplement. It is stacking: a multivitamin, a B-complex, a magnesium product containing additional B6, an energy drink, a sleep product with additional vitamins. Each product may look reasonable by itself.

Your body doesn't see five different labels. It experiences the combined dose.

Does the form matter? Sometimes. Vitamin B12 may be cyanocobalamin, methylcobalamin, hydroxocobalamin, or adenosylcobalamin. B6 may be pyridoxine or P5P. Folate may be folic acid or 5-MTHF. Different forms can differ in stability, metabolism, and suitability — as the PNPO example shows. But the word active, methylated, or bioavailable on a bottle doesn't automatically mean better outcomes for everyone. The question remains: right form, for whom, and for what purpose?

What about cycling supplements? There's insufficient evidence that compounds like curcumin or berberine routinely need to be cycled simply because they're pharmacologically active. A much stronger principle is to reassess: why did you start it, is it working, is the original indication still present, has new evidence emerged, should it be continued? Some supplements are appropriate for weeks, some for months, some indefinitely — and in conditions like biotinidase deficiency, supplementation may literally be lifelong. The Right Amount of Time depends on the reason.

THE UGLY — When the Bottle Becomes the Problem

In the United States, dietary supplements are regulated differently from prescription medications — the FDA generally does not approve them for safety and effectiveness before they reach the market. Manufacturers still have legal responsibilities for safety, manufacturing, and truthful labeling, but the system is not equivalent to pharmaceutical premarket approval.

Products marketed as supplements have been found to contain undeclared pharmaceutical ingredients, different amounts of ingredients than stated on the label, contaminants, or formulations different from what was actually studied. Recent FDA testing has identified products marketed for weight loss or sexual enhancement containing undeclared drug ingredients. That's not a theoretical concern.

Botanical supplements add another layer. Ashwagandha is a useful example — different products may contain root, leaf, or combinations of plant parts, with different extraction methods producing very different concentrations of active compounds. Clinical evidence generated with one standardized extract cannot automatically transfer to every bottle labeled "ashwagandha." There are also documented cases of liver injury associated with ashwagandha products; the absolute risk appears low, but the bigger lesson is broader:

Botanical name ≠ standardized medicine.

Plant part matters. Extraction method matters. Dose matters. Manufacturing matters. And the actual product studied matters.

How Do You Know What's Actually in the Bottle?

This is where independent third-party verification can help:

But remember: third-party verification answers only part of the question. There are really three different questions: (1) Does the bottle contain what it says it contains? (2) Is this supplement reasonably safe and appropriate for me? (3) Does it actually accomplish what I am taking it for? A quality seal primarily helps with Question 1. It does not automatically answer Questions 2 and 3. Neither practitioner grade nor over-the-counter is itself a scientific measure of effectiveness — an expensive supplement can be poorly suited to your needs, and a reasonably priced one can be exactly what you need. It really all depends.

The Perisson Six Rights of Supplementation

Before adding another bottle, ask six questions.

1. The Right Tool — Is supplementation actually the best intervention, or could food, lifestyle, or treating an underlying condition address the problem more appropriately?

2. The Right Person — Age, pregnancy, diet, medications, kidney and liver function, medical history, and labs all matter. Nutrigenomics can contribute information, but genetic variants should be interpreted alongside the rest of the person, not become supplement prescriptions by themselves.

3. The Right Reason — Am I correcting a deficiency, addressing increased requirements, compensating for impaired absorption, replacing ongoing losses, or deliberately using a compound for a therapeutic effect? "It's good for you" is not a sufficiently specific reason.

4. The Right Dose — What dose has demonstrated benefit, at what point might harm occur, and am I receiving the same ingredient somewhere else? More is not automatically better.

5. The Right Time — Does timing affect absorption, tolerability, medication interactions, or lab testing? Timing matters, but that doesn't mean every supplement needs an elaborate schedule.

6. The Right Amount of Time — How long should I take it, how will I know it's working, and when should we reassess? The goal is not necessarily to stop every supplement — it's to continue it for as long as there remains a sound reason to do so.

What this means for you

If you're an Early Awakener, still early in paying attention: the temptation is to reach for a bottle before asking why. Before you add anything, start with the first question in this issue instead — "Why would my body need this in the first place? Is something preventing me from getting, absorbing, or using what I already take in?" Investigate before you supplement.

If you're a Recalibrator, already managing multiple medications, conditions, or supplements: you're the person most exposed to stacking — the quiet overlap between five well-intentioned products that, combined, your body experiences as one dose. Your version of this month's question: "If I laid out everything I currently take — medications and supplements together — would my doctor or pharmacist see anything stacking that I can't see myself?"

If you're a Forward-Looker, stable and focused on staying that way: your risk isn't starting something inappropriate, it's never stopping something that's outlived its reason. Make reassessment a habit, not a one-time event: "For each supplement I've taken for more than a year, do I actually know why I'm still taking it?"

Before You Buy Another Supplement...

Rather than applying all six rights to every bottle in your cabinet right now, start smaller — pick just one.

The Goal Isn't More Supplements. And It Isn't No Supplements.

It is easy to fall into one of two camps: "Supplements are natural, therefore they are safe and good." Or: "Supplements aren't pharmaceuticals, therefore they don't really do much." Neither is accurate. Something biologically active enough to help you can also be biologically active enough to interact with you.

That is why I don't believe the goal should be to build the biggest supplement stack. Nor should the goal be to avoid supplements at all costs. Food is still first. Nutrient-dense food provides not simply isolated vitamins and minerals but protein, essential fats, fiber, phytonutrients, and thousands of compounds interacting within the biological system we call the human body.

Then, when supplementation meaningfully adds to our ability to help an individual optimize health, we use it deliberately. We ask why. We choose carefully. We monitor. And we reassess.

The Right Tool, for the Right Person, for the Right Reason, at the Right Dose, at the Right Time, for the Right Amount of Time.

Because ultimately: the goal is not to optimize your supplement regimen. The goal is to optimize your body's function.

This newsletter is free for now. If it's useful to you, share it with someone who'd benefit — and if you're new here, welcome! The first few issues are always free to read, so you can catch up anytime.

You'll hear from me like this every second Tuesday of the month.

To your health,
Oluwakemi Olowoyo, MD
Perisson Optimized Health
Live abundantly, optimize your health.

This newsletter is educational in nature and is not a substitute for personalized medical care from your own physician. Always talk with your doctor before starting, stopping, or changing any supplement or medication.

Sources referenced in this issue:
Centers for Disease Control and Prevention, National Center for Health Statistics. Dietary Supplement Use Among Adults: United States, 2021–2023. NCHS Data Brief No. 561. 2026.
Davis DR, Epp MD, Riordan HD. Changes in USDA food composition data for 43 garden crops, 1950 to 1999. J Am Coll Nutr. 2004;23(6):669-682.
Jovanovski E, Yashpal S, Komishon A, et al. Effect of psyllium (Plantago ovata) fiber on LDL cholesterol and alternative lipid targets, non-HDL cholesterol and apolipoprotein B: a systematic review and meta-analysis of randomized controlled trials. Am J Clin Nutr. 2018;108(5):922-932.
Centers for Disease Control and Prevention. Folic Acid and MTHFR Gene Variant. CDC Division of Birth Defects and Infant Disorders.
LiverTox: Clinical and Research Information on Drug-Induced Liver Injury. Ashwagandha. National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK).