Three quarters of Americans take supplements.

YOUR HEALTH — Issue No. 24

Almost every day in my practice I get a version of the same conversation.

A patient comes in. Before I can ask what brought them in, they start listing what they are taking. Fish oil. Turmeric. Collagen. Ashwagandha. CoQ10. Elderberry. Sometimes eight or ten things. They want to know if they are okay to take together, whether they interact with their medications, and whether I think they are working.

And then — in the same visit — that same patient hesitates when I bring up a medication their cardiologist recommended. Or tells me they stopped their statin because they read something online.

I am not frustrated by this. I understand it completely.

Taking a supplement feels proactive. It feels like something you chose to do for yourself — not something a doctor told you to do. That instinct to be engaged in your own health is something I genuinely want to support.

My job is not to talk you out of supplements. It is to help you know which ones are worth your time and money — and which ones are not delivering what the label suggests.

What most people don't know about how supplements are regulated

Prescription medications and over-the-counter drugs must prove they are safe and effective before they reach the market. The FDA reviews clinical trial data. The bar is high and the process is long.

Dietary supplements operate under a different law entirely — the Dietary Supplement Health and Education Act of 1994. Under this law, the FDA is not authorized to approve supplements for safety or effectiveness before they are marketed. In many cases, manufacturers can legally put a supplement on the market without notifying the FDA at all. The burden is on the FDA to prove a product is unsafe after it is already being sold — not on the manufacturer to prove it works before selling it.

This is not a fringe critique. It is the FDA's own description of its authority.

What this means practically: the label on a supplement bottle can say it "supports immune health" or "promotes cognitive function" without any clinical evidence that it does either. The word "supports" is doing a lot of work on those labels.

This does not mean every supplement is useless. Some have real evidence behind them. But it does mean that the supplement aisle is not operating under the same evidentiary standards as the pharmacy counter — and most patients have never been told that plainly.

"Natural" doesn't mean harmless

This is worth saying clearly because it is one of the most common assumptions I encounter.

Natural describes where something came from. It does not tell you whether it works, whether it is safe at a given dose, or whether it interacts with something else you are taking.

A few examples worth knowing:

St. John's Wort — one of the better-studied botanical supplements for mild depression, but one of the most clinically significant for drug interactions. It reduces the effectiveness of many common medications including antidepressants, blood thinners, birth control pills, and certain heart medications. This is not a theoretical concern — it is a documented, serious interaction.

Vitamin K — directly opposes the mechanism of warfarin. Patients on warfarin who change their vitamin K intake — from food or supplements — can have meaningful changes in their INR. This is why providers managing warfarin ask about dietary consistency.

High-dose fish oil — at high doses, omega-3 fatty acids have blood-thinning effects. In most patients this is modest. In patients already on anticoagulants or about to have surgery, it deserves a conversation.

Magnesium — can interfere with the absorption of certain antibiotics and medications when taken at the same time. Timing matters.

The practical takeaway: your provider and pharmacist need to know everything you are taking — prescription, over-the-counter, and supplements. A complete picture allows a complete review.

Do we actually need supplements?

The honest answer is: it depends — and it depends on factors most supplement marketing ignores entirely.

A healthy adult eating a genuinely varied diet — adequate protein, a wide range of vegetables and fruits, whole grains, legumes — has limited need for most supplements. The research consistently shows that nutrients obtained from food are better absorbed, better utilized, and come packaged with a broader range of cofactors than isolated supplements can replicate.

The problem is that most American adults are not eating that diet. The average American falls short on fiber, vegetables, vitamin D, magnesium, and omega-3 fatty acids from diet alone. So the question is not really "do supplements work" — it is "what does this person's diet and health status actually look like, and are there specific gaps worth addressing?"

Certain populations have genuine, evidence-supported needs that diet alone often cannot meet. Adults over 50 are at the top of that list.

Why over 50 changes the conversation

Vitamin B12 — absorption decreases with age. The stomach produces less acid over time, and acid is required to separate B12 from food proteins before it can be absorbed. Adults over 50 absorb supplemental B12 more reliably than food-bound B12 — which is why many guidelines specifically recommend supplemental B12 in this age group. The decline is accelerated further in patients on metformin or long-term proton pump inhibitors.

Vitamin D — synthesis in the skin declines significantly with age. Older adults spend less time outdoors, have thinner skin that is less efficient at making vitamin D from sunlight, and have reduced kidney conversion to the active form. Deficiency is common in adults over 65 and directly affects bone health, muscle function, and immune response. I want to know your actual vitamin D level before recommending a dose. A simple blood test tells me whether there is a need for replacement or not.

Muscle mass — declines naturally after age 30 at approximately one to two percent per year, accelerating after 60. This is called sarcopenia, and it is one of the strongest predictors of functional decline, falls, and loss of independence in older adults. Protein intake and resistance training are the primary defenses. Supplements that support those two things have a legitimate role in the over-50 population in a way they simply do not in a healthy 25-year-old. The Member deep-dive this week covers this more.

Fish oil — what the label isn't telling you

Fish oil is one of the most commonly purchased supplements in America — and a good example of how supplement labels can mislead even well-informed patients.

First, the terminology: omega-3 is the nutrient. EPA and DHA — eicosapentaenoic acid and docosahexaenoic acid — are the two clinically active omega-3 fatty acids. Fish oil is the most common delivery vehicle. Algal oil delivers the same EPA and DHA from plant sources — relevant for anyone who does not eat fish or prefers a plant-based option.

Here is the label problem most patients never notice: a bottle labeled "1,200mg Fish Oil" may contain only 360mg of actual EPA and DHA combined. The rest is other fats that do not carry the same clinical evidence. What matters clinically is the EPA plus DHA content — not the total fish oil milligrams. Read the supplement facts panel, not the front of the bottle.

What to look for:

For general nutritional support — look at the EPA plus DHA content per serving, not the total fish oil amount. A minimum of 500mg combined EPA and DHA per serving is a reasonable target.

For cardiovascular risk reduction — do not assume that taking more OTC fish oil reproduces the evidence from prescription-strength therapy. The REDUCE-IT trial studied icosapent ethyl at 4 grams per day in high-risk patients already on statins and showed a meaningful reduction in cardiovascular events. That is a different product, a different dose, a different population, and a different evidence base from standard OTC fish oil. If cardiovascular risk reduction is your specific goal, that conversation belongs with your provider.

On quality and freshness:

Because supplements are not regulated for potency and purity the way medications are, third-party testing matters. Look for certification from USP, NSF International, or IFOS — the International Fish Oil Standards program — when choosing a fish oil product. These organizations independently verify that what is on the label is actually in the bottle, and that the product is free from heavy metals and other contaminants.

Fish oil oxidizes with exposure to heat and light. The smell test is real — fresh fish oil should smell mild and clean. If it smells strongly fishy or off, it has likely gone rancid. Refrigerate after opening. This slows oxidation, extends shelf life, and reduces the fish burp effect that leads many patients to stop taking it.

The questions worth asking before adding anything new

Most of my supplement conversations come down to a few questions I want every patient asking before adding something to their routine:

What specific problem am I trying to solve — and is there a supplement with evidence that actually matches that goal?

Do I know my actual levels — vitamin D, B12, iron — before supplementing? Or am I guessing?

Does my provider and pharmacist know everything I am taking?

Is the product third-party tested?

Those four questions filter out the majority of supplement spending that does not deliver meaningful benefit.

Plain Supplement

Plain Medicine has a free evidence tool at tools.plainmedicine.health/supplements — select your health goals, list what you are taking, and get a plain read on whether the published research supports the match. No products to sell. Nothing to buy. Just the evidence, matched to what you are actually trying to accomplish.

Something worth saying plainly:

Three quarters of Americans take supplements. The instinct behind that is a good one — people are trying to be proactive about their health, trying to feel better, trying to stay ahead of problems before they become problems.

That instinct deserves honest guidance — not dismissal.

The evidence on most supplements is not as strong as the marketing suggests. But for some supplements, for the right person, for the right reason — the evidence is there. Knowing the difference is what this issue is about.

The Member deep-dive this week covers the three supplements I actually recommend in clinical practice — the evidence behind each one, what to look for on the label, the right dose, and who should use caution. Including creatine — which consistently surprises my patients when I bring it up.

Next week: Cognitive decline and dementia prevention — what the evidence shows about modifiable risk factors.

Plain Medicine is published for educational purposes only and does not constitute medical advice or establish a patient-provider relationship. Always consult your healthcare provider before making medical decisions.

— Kyle