Supplements: Why They Only Work After the Foundations Are in Place

Five things to understand about supplements

1. A supplement is regulated like a food, not a drug. The FDA does not approve a supplement for safety or effectiveness before it is sold; the company selling it is responsible for that 4.

2. Most of the null results come from people who did not need the nutrient. The VITAL trial, the DO-HEALTH trial and the U.S. Preventive Services Task Force review all studied largely replete adults 1 5 6.

3. Deficiency is common, testable and correctable. By the 20 ng/mL definition, about four in ten American adults are low in vitamin D, and B12 deficiency rises with every year on a vegan diet 7 8.

4. Nutrients from food and nutrients from pills are not the same claim. In a cohort of nearly 31,000 adults, adequate intake of several nutrients was linked to lower mortality only when it came from food 9.

5. More is not better. High-dose vitamin E and beta carotene in smokers are the two clearest examples of a supplement doing harm 10 11.

What are supplements, really?

The word matters. "Supplement" means an addition to something that already exists. In the law, that something is your diet. In practice it is wider than that: a supplement is an addition to your whole way of living, and it borrows its usefulness from everything else you are doing.

About half of U.S. adults use at least one. In the national survey data that run through 2012, 52 percent of adults reported taking a supplement in the previous 30 days, a figure that held steady for more than a decade even as multivitamin use slipped from 37 to 31 percent and vitamin D and fish oil use climbed 2. That is more than 100 million people making a decision few were ever taught how to make.

Here is what the regulation means in practice. A company can sell a supplement without proving it works. It cannot legally claim the product treats or cures a disease, but it can say the product "supports" a body system, and the line between those two is thin 4. The FDA can act against a product after it is on the market if it is adulterated or mislabeled. That is a real safeguard, and it runs behind the product rather than in front of it.

So the responsibility sits with the person taking the product and with whoever is advising them. That is the reason this page exists.

Why supplements are supplemental

I want to reframe this at the start, because the culture gets it backwards. A supplement looks like a shortcut. It behaves like a patch. A patch is a fine thing when there is a small hole in a sound structure, and it is useless when the structure itself is failing. Nothing you read in favor of supplements on this site cancels that order of operations.

Take a nutrient as simple as vitamin D. It is fat-soluble, so it needs fat in the meal to be absorbed; in one trial, older adults who took vitamin D3 with a fat-containing meal absorbed 32 percent more of it than those who took it with a fat-free meal 12. Vitamin D and magnesium work as teammates, magnesium is involved in activating vitamin D, and isolated nutrients taken alone tend to be absorbed less well than nutrients taken together the way food delivers them. That is a clinical view, and the food-matrix research points the same direction. A pill's usefulness is conditional on what surrounds it: the meal, the mineral status, the gut lining, and the sleep that repairs the gut lining.

The position I keep coming back to reads: Food comes first. Nutrient-dense, real, whole foods before supplements, before anything. That is not a rule against supplements. I take them and recommend them; food is more important, and so is your sleep, and so is your movement.

The honest limit of that position is worth naming. The evidence that whole-food-based supplement forms absorb better than isolated forms is thinner than the enthusiasm for them, mine included. Some forms have data behind them, such as methylated B vitamins for people with certain gene variants, and many do not. Where I state a preference for a form on this site, treat it as a preference informed by practice rather than settled science.

The six foundations that have to come first

They are ranked by how often a missing one explains the symptom you hoped a supplement would fix.

1. A whole-food diet

This is the foundation the other five stand on, and it is the one supplements are most often used to avoid. In a cohort of 30,899 U.S. adults followed for a median of six years, adequate intake of vitamin A, vitamin K, magnesium, zinc and copper was associated with lower all-cause or cardiovascular mortality, and the association held only when the nutrients came from food. Supplement use itself was not linked to lower mortality, and calcium above the tolerable upper limit, mostly from supplements, was linked to higher cancer mortality 9. That is observational data with the usual limits, and it is still the clearest single picture available of food versus pill.

On the other side of the ledger, ultra-processed food exposure was associated with higher risk of cardiovascular death, type 2 diabetes, anxiety and all-cause mortality across an umbrella review covering 9.9 million people 13. And when a food pattern was tested as an intervention rather than observed, a Mediterranean diet built on extra-virgin olive oil or nuts reduced major cardiovascular events by about 30 percent in high-risk adults 14. The "supplement" in that trial was olive oil and a handful of nuts.

Why: Food delivers nutrients with their cofactors, their fiber and their fat, in the amounts the body evolved to handle. The 50 most nutrient-dense foods are where to start, long before any bottle.

2. Sleep

Most repair happens while you sleep. Across 16 prospective studies covering 1.38 million people, short sleep was associated with a 12 percent higher risk of death and long sleep with a 30 percent higher risk, the second number most likely reflecting underlying illness rather than sleep itself 15. No nutrient reverses the effect of a chronically short night.

Sleep is also where nutrient status gets used. Immune repair, the clearing of metabolic waste from the brain and the resetting of the cortisol rhythm all happen overnight. Shortchange it and the day's vitamin D, magnesium and protein have less to work with. If sleep deprivation is the reality, fix it before fixing the cabinet.

Why: Sleep is the one foundation that cannot be outsourced, and it sets the hormonal environment every other input works inside.

3. A managed stress load

Chronic psychological stress is associated with depression, cardiovascular disease, faster progression of HIV and slower wound healing, and the pathways run through the stress-hormone axis and the immune system 16. Stress raises cortisol, cortisol changes how the gut absorbs and how the kidneys excrete, and the loop feeds itself: stress burns through minerals, and low mineral status worsens the stress response.

This is the foundation most often "treated" with a supplement, because it is the hardest to change. An adaptogen or a mineral can take the edge off. It cannot remove the load. If your cortisol rhythm is flat or inverted, the fix is upstream, in how the day is structured, and the chronic stress guide covers it.

Why: Stress is a nutrient-depleting state, so supplementing against it without reducing it is pouring water into a bucket with a hole in it.

4. Daily movement

In a harmonized analysis of eight cohorts that measured activity with accelerometers rather than questionnaires, higher total physical activity at any intensity was associated with substantially lower mortality, and the most sedentary quarter of adults had more than two and a half times the death rate of the least sedentary 17. The curve is steepest at the low end, which means the first 20 minutes of walking a day buys more than the last 20 minutes of a marathon.

Movement also rebuilds the machinery that uses nutrients. Across nearly 6,000 participants, exercise training increased the mitochondrial content of skeletal muscle, with gains that scaled with how much and how hard people trained 18. No supplement builds mitochondria the way a hard walk uphill does.

Why: Movement changes cellular energy machinery in a way no pill replicates, and the benefits of exercise start at doses almost anyone can meet.

5. Sunlight

Vitamin D is made in the skin from ultraviolet B light, and sensible sun exposure, along with fortified foods and supplements, is one of the three ways a person gets it 19. By the 20 ng/mL cutoff, 41.6 percent of U.S. adults were deficient in 2005 to 2006, and the rate reached 82 percent among Black adults and 69 percent among Hispanic adults 7. That is one of the reasons vitamin D is the nutrient I test first.

Morning light does a second job that has nothing to do with vitamin D. It anchors the circadian clock, which sets cortisol, melatonin and the timing of hunger for the whole day. Ten minutes outside within an hour of waking, without sunglasses, is one of the cheapest interventions you can make. The benefits of sunlight go well past one vitamin.

Why: Sunlight sets the clock that every other foundation runs on, and it is the one input a vitamin D capsule only partly replaces.

6. Relationships

Across 148 studies and 308,849 people, adults with stronger social relationships had 50 percent higher odds of survival over the follow-up period, an effect the authors placed alongside established risk factors such as smoking and inactivity 20. Loneliness is inflammatory, and connection lowers the stress hormones that suppress repair. Eat at least one meal a day with another person, and ask for help early, because you were not built to heal alone.

Why: Relationships shape stress, sleep and eating at the same time, so they move every other foundation at once.

A simple rule: if a symptom has not responded to a supplement, look for the missing foundation.

Do supplements work? What the big trials say

The internet has split into camps here, and both are half right. Here is the two-sided version.

The skeptic camp is right that:

• Across 21 randomized trials in 91,074 adults, multivitamin-mineral supplements had no effect on all-cause mortality, vascular mortality or cancer mortality 21.

• The 2022 U.S. Preventive Services Task Force review of 84 studies found vitamin and mineral supplementation gave little or no benefit for preventing cancer, cardiovascular disease or death in healthy adults, with a small possible reduction in cancer incidence with multivitamins 1.

• In the VITAL trial, 2,000 IU of vitamin D3 a day for about five years did not reduce invasive cancer or major cardiovascular events in 25,871 adults 5.

• In DO-HEALTH, three years of vitamin D3, omega-3 or a home strength program, alone or combined, did not significantly improve blood pressure, fractures, physical performance, infections or cognition in 2,157 healthy adults over 70 6.

…but overreaches when it claims:

• That supplements do nothing. Every one of those trials enrolled people who were largely replete and healthy at baseline. They tested adding a nutrient to people who had enough of it.

• That the calcium and vitamin E harm signals apply to every supplement. They apply to high doses of specific nutrients in specific populations.

• That a null result on mortality means a null result on how a person feels.

The supplement industry is right that:

• Deficiency is common. Four in ten American adults were low in vitamin D by the 20 ng/mL definition, and B12 deficiency among vegans and long-term vegetarians runs from common to near-universal depending on the group studied 7 8.

• Correcting deficiency does something. In a small trial of overweight adults with low vitamin D, 16 weeks of 4,000 IU a day slowed one measure of epigenetic aging by about 1.85 years compared with placebo 22.

• Some nutrients show benefit even in reasonably healthy older adults. Daily multivitamins produced a small improvement in global cognition and episodic memory in the COSMOS substudies, an effect the authors described as equivalent to about two years less cognitive aging 23. And in a post-hoc DO-HEALTH analysis, omega-3 alone slowed three DNA-methylation aging clocks over three years, with the biggest effect when omega-3, vitamin D and exercise were combined 24.

…but overreaches when it claims:

• That everyone needs a cabinet full. The COSMOS effect is small and in adults over 60. The omega-3 effect is measured in months, in a secondary analysis.

• That daily vitamin D lowers cancer deaths for everyone. In the largest individual-patient meta-analysis, the pooled result was not significant; only the daily-dosing subgroup showed a roughly 12 percent reduction 25.

• That "natural" means safe at any dose. High-dose vitamin E was associated with higher all-cause mortality in a meta-analysis of 19 trials, and beta carotene raised lung cancer incidence by 18 percent in male smokers 10 11.

The resolution reframes the question. "Do supplements work?" has no answer, because the honest reading is that the evidence is split along one line: deficient or replete. The question that has an answer is "Are you short on something, and how would you know?" Everything that follows is built to answer it.

One more thing, because it is my byline. My stated position is that targeted supplementation with nutrients like vitamin D, magnesium and omega-3s is essential for correcting deficiencies when it is guided by bloodwork. The mainstream reading of the trials above is more skeptical. Where that position goes further than the trial data strictly supports is in how often subclinical shortfalls are present and worth addressing, and in a preference for whole-food-based forms. Those are clinical judgments, held and attributed as such, and never dressed up as trial results.

When is it reasonable to supplement?

The way to decide whether you need a nutrient is the same every time: what is missing, why is it missing, and can food fix it. Here are the situations where the answer to the third question is often no.

The situations where supplementing is reasonable, and how you would know

A few of these deserve a sentence each, because they are the ones I see most.

Vitamin D. Roughly four in ten adults are below 20 ng/mL, and the number climbs with darker skin and with every degree of latitude away from the equator 7. I want my patients above 50 ng/mL, and nobody knows where they sit without a test. The signs of vitamin D deficiency are vague enough that testing beats guessing.

Vitamin B12. Vegans and long-term vegetarians are at real risk, with deficiency rates that rise with years on the diet and run higher among vegans than among vegetarians 8. Older adults lose stomach acid and with it the ability to free B12 from food. This is the one deficiency where a supplement rarely needs a debate, because the food sources are animal foods and some people will not eat them. Read the B12 deficiency symptoms if fatigue and tingling are part of your picture.

Iron. Iron-deficiency anemia is one of the most common nutritional problems in the world, and its causes are blood loss, low intake and malabsorption 26. Because the cause decides the fix, I never want anyone taking iron without a ferritin result and a reason. The iron deficiency guide covers both the food and the testing side.

Magnesium. Serum magnesium is a poor marker because the body defends blood levels at the expense of the cells, so the signs of magnesium deficiency are a better first screen than the standard lab. The evidence for correcting it is real and modest: across double-blind trials magnesium lowered blood pressure by a small amount, and in older adults with insomnia it produced small improvements in sleep measures on low-to-moderate quality evidence 27 28.

One first-person detail, because it is on the record. I once tested low in a single B vitamin, riboflavin, and correcting that one measured shortfall is what gave me my energy back. The lesson was never "take B vitamins." It was "test, then correct the thing that is low."

How to evaluate a supplement

Here is the framework, without a single product named, because the framework is what transfers to whatever you are holding.

1. Does the evidence match your situation?

The most common evidence error is reading a positive trial in deficient people and applying it to someone who is not deficient, or reading a null trial in replete people and concluding a nutrient is useless for someone who is low. Before taking anything, ask: who was in the study, what did they lack, and what did the study measure? A trial that moved a blood marker did not necessarily move a symptom. A trial that moved a symptom in people over 70 says little about a 35-year-old.

2. Is the form one your body can use?

Forms matter, and this is where clinical experience and the research overlap most. Fat-soluble vitamins need fat in the meal; a vitamin D3 dose taken with a fat-containing meal was absorbed 32 percent better than the same dose taken with a fat-free meal 12. B vitamins in their methylated or activated forms bypass a conversion step that some people handle poorly. Minerals bound to amino acids tend to be gentler on the gut than oxide forms. My preference, stated as a preference, is for forms that come from or resemble food, with their cofactors present, and for nutrients that work together rather than in isolation.

3. Is the dose inside the evidence and below the upper limit?

More is not better, and the two clearest cautionary tales are worth knowing by name. A meta-analysis of 19 trials found that vitamin E at 400 IU a day or more was associated with higher all-cause mortality, with the risk rising above about 150 IU a day, though most of the high-dose trials were in people with chronic disease 10. In the ATBC trial, beta carotene supplements raised lung cancer incidence by 18 percent in male smokers 11. Calcium from supplements above 1,000 mg a day tracked with higher cancer mortality in the NHANES cohort 9. Every nutrient has a tolerable upper intake level published by the National Academies. A label that sits above it calls for a reason and a clinician, not a coupon.

4. Is it tested by someone other than the company selling it?

Because the FDA does not test a supplement before it is sold, third-party verification is the closest thing to an outside check that the bottle contains what the label says and does not contain what it should not 4. Look for a named independent testing program on the label, and ask for a certificate of analysis. A company that will not show its testing is telling you something.

5. Is the category one with a known adulteration problem?

From 2007 to 2016 the FDA identified 776 adulterated supplements from 146 companies, and most were marketed for sexual enhancement, weight loss or muscle building, with undeclared prescription drugs inside them 29. Those same categories drive the emergency room data: an estimated 23,000 ER visits a year are attributed to supplement adverse events, and among young adults the visits are commonly cardiovascular symptoms from weight-loss and energy products 30. A basic vitamin D or magnesium product is not where that risk lives. A "fat burner" from an unfamiliar website is.

6. Does it interact with anything?

Supplements interact with medications and with each other. Herbs can change how the liver clears drugs, minerals compete for absorption, and fat-soluble vitamins accumulate. Bring the bottle to your physician or pharmacist.

What to check before you take anything

The supplement mistakes that cost you most

They are ranked by how much harm and wasted money each one causes you.

1. Supplementing instead of sleeping. A stress-support blend at 11 p.m. will not repair what six hours of sleep is breaking. Fix the schedule first.

2. Never testing. Vitamin D, B12, ferritin, red cell magnesium and a basic metabolic panel cost less than a few months of guessing. Test, correct, retest.

3. Assuming more is better. The vitamin E, beta carotene and calcium data above are the reason every nutrient has an upper limit 9 10 11.

4. Taking isolated nutrients without their partners. Vitamin D without magnesium, zinc without copper, calcium without vitamin K2 and D. That is a clinical view rather than a trial result, and it is the way food delivers nutrients in the first place.

5. Buying the marketing. "Clinically studied" on a label may refer to one ingredient, at a different dose, in a different population. Read the study.

6. Ignoring interactions. Herbs and medications do not always mix, and nobody checks unless you ask.

7. Treating a symptom whose cause was never found. Fatigue can be iron, thyroid, sleep apnea, depression or a dozen other things. A supplement that helps a little can delay the test that finds the cause.

8. Stacking a dozen products and changing them all at once. If something helps or harms, nobody will know which one did it. Add one thing at a time, for long enough to judge it.

What food first means in practice

People hear "food first" and assume it means anti-supplement. It does not. I take them, and my patients take them. Food first is a sequence. The reason it is the right sequence comes from the food matrix: nutrients in a whole food arrive with the fat, the fiber, the cofactors and the other nutrients that help the body absorb and use them. Food functions together as a whole, and a fish is a better delivery system for omega-3s than most capsules. When a patient is going to supplement omega-3s anyway, I steer them toward the less-processed forms, and I still tell them to eat the sardines.

In practice, most of the plate is vegetables, fruit, quality protein, healthy fats and, if you tolerate them, properly prepared grains and legumes. Organ meats, shellfish, eggs, fermented foods and bone broth carry more nutrients per bite than almost anything in a bottle. Ultra-processed food displaces the foods that would have closed the gap in the first place, which the ultra-processed foods guide explains.

Then, and only then, comes the question of what food could not close. On a vegan diet, that is B12. In Minnesota in February, that is often vitamin D. With heavy periods, it may be iron. Those are real gaps, and closing them with a supplement is the right use of one.

How to think about supplementation: an order of operations

Here is the sequence, in order.

1. Audit the six foundations. Whole-food diet, sleep, stress load, movement, sunlight, relationships. Write down which ones are missing. Most people find two.

2. Fix the cheapest missing foundation first. Morning light and a consistent bedtime cost nothing. Start there.

3. Test before you supplement. At minimum: 25-hydroxyvitamin D, B12, ferritin, a complete blood count and a metabolic panel. Add red cell magnesium if sleep, cramps or anxiety are part of the picture.

4. Correct the specific shortfall. Choose the nutrient the test named, in a form the body can use, at a dose inside the evidence and below the upper limit, from a product with third-party testing.

5. Retest in 8 to 12 weeks. A supplement that did not move the marker is either the wrong form, the wrong dose, or the wrong diagnosis.

6. Stop what is not doing anything. Every product in your cabinet should be able to answer one question: why is it there?

To see how that thinking turns into a daily rhythm, the supplement routine guide is the practical companion to this page: it covers timing, food pairing and how to structure a day. This page is the philosophy behind it.

The bottom line

Frequently asked questions

References

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This article is for educational purposes and is not medical advice. Supplements can interact with medications and medical conditions. Use them alongside, never instead of, medical care, and talk with your physician or pharmacist before starting, stopping or combining any supplement, especially if you are pregnant, breastfeeding, managing a chronic condition or taking prescription medication.