We score supplements for a living. We also think most people are buying ones they don't need.
That's not a contradiction. It's the whole point. The supplement industry is worth over $60 billion in the US alone, and a significant chunk of that spending goes toward products that do nothing for the people taking them. Not because the products are bad. Because the people don't have the deficiency the product addresses.
Supplements fill gaps. They don't replace a diet. If you eat a reasonably varied diet with vegetables, protein, whole grains, and some fruit, you're covering most of your bases. The word "supplement" is right there in the name.
But some gaps are common enough that they're worth checking for. And a few are so widespread that supplementation makes sense as a default.
The supplements most people actually need
Vitamin D3
This is the closest thing to a universal recommendation. An estimated 42% of US adults are deficient in vitamin D. If you live above the 37th parallel (roughly north of Richmond, Virginia), your skin cannot produce adequate vitamin D from sunlight between October and April. If you work indoors, wear sunscreen consistently, or have darker skin, your risk is higher year-round.
The evidence for supplementation is strong. 1,000-2,000 IU daily is a reasonable baseline for most adults. It's cheap, safe at those doses, and addresses a deficiency that's genuinely difficult to fix through food alone - you'd need to eat fatty fish almost every day.
See our full Vitamin D3 scorecard
Vitamin B12
If you're vegan or vegetarian, you need to supplement B12. No plant food provides adequate B12 in a reliable, bioavailable form. This isn't debatable - it's basic biochemistry.
Adults over 50 should also consider B12 supplementation. The body's ability to absorb B12 from food declines with age due to reduced stomach acid production. Methylcobalamin is the preferred form, though cyanocobalamin works fine for most people.
See our full Vitamin B12 scorecard
Folate
Women of childbearing age should take folate (400-800 mcg daily), especially if pregnancy is possible. The evidence for neural tube defect prevention is among the strongest in all of nutrition science. The critical window is early pregnancy - often before a woman knows she's pregnant - which is why preconception supplementation matters.
Methylfolate is preferred over folic acid for people with MTHFR variants, which affect roughly 25-40% of the population.
Iron (with a major caveat)
Women with heavy menstrual periods, endurance athletes, and vegetarians are at elevated risk for iron deficiency. Symptoms include fatigue, weakness, poor concentration, and cold intolerance.
Here's the caveat: do not supplement iron without a confirmed deficiency via blood work. Unlike most vitamins, excess iron is toxic. Your body has no efficient mechanism to excrete it. Iron overload damages the liver, heart, and pancreas. Get tested first. If you're deficient, supplement under medical guidance. Iron bisglycinate causes fewer GI side effects than ferrous sulfate.
Omega-3 fatty acids (EPA/DHA)
If you eat oily fish (salmon, mackerel, sardines, anchovies) at least twice a week, you're probably fine. Most Americans don't come close. The typical Western diet provides far more omega-6 than omega-3, and the cardiovascular and anti-inflammatory evidence for EPA/DHA is solid.
Look for supplements that provide at least 500 mg combined EPA/DHA per serving. Many cheap fish oil capsules contain far less than their label suggests per effective dose.
See our full Fish Oil scorecard
Supplements that make sense for specific situations
Magnesium
Roughly half of Americans don't meet the RDA for magnesium through diet. Modern soil depletion and processed food consumption are the main drivers. If you experience muscle cramps, poor sleep, or eat a diet heavy in processed foods, magnesium supplementation is reasonable. Glycinate is well-absorbed and less likely to cause digestive issues than oxide or citrate.
See our full Magnesium Glycinate scorecard
Creatine
If you do any form of resistance training or high-intensity exercise, creatine monohydrate is one of the most well-studied and effective supplements available. 3-5g daily. No loading phase needed. The evidence base spans decades of research with consistent positive results for strength, power output, and muscle recovery. It's also remarkably cheap.
See our full Creatine scorecard
Probiotics
After a course of antibiotics, a quality probiotic can help restore gut flora. There's also reasonable evidence for specific strains in specific GI conditions (IBS, antibiotic-associated diarrhea). But the evidence does not support daily probiotic use as a general "wellness" supplement for healthy people with no digestive complaints. Save your money.
See our full Probiotic scorecard
Where most people waste money
Multivitamins
The largest and longest studies on multivitamins - including the COSMOS trial and the Physicians' Health Study II - show minimal benefit for well-nourished adults. If you eat a varied diet, a multivitamin is expensive insurance against a problem you don't have. The doses of individual nutrients are often too low to correct an actual deficiency and too scattered to serve a targeted purpose.
See our full Multivitamin scorecard
"Immune boosters"
No supplement "boosts" a healthy immune system. That's not how immunity works. An overactive immune system is called an autoimmune disease. What vitamin C and zinc can do is support normal immune function and may reduce cold duration modestly - but only if you're deficient. Mega-dosing vitamin C beyond what your body can absorb just creates expensive urine.
Detox supplements
Your liver and kidneys detoxify your body continuously. They're very good at it. No supplement improves on millions of years of evolutionary engineering. "Detox" and "cleanse" products are marketing, not medicine.
Proprietary blends
If a label says "proprietary blend" followed by a list of 15 ingredients and one total weight, you have no idea what you're getting. Most ingredients in these blends are present at doses far below what any study has ever tested. You're paying for label decoration. We factor this into every transparency score on this site.
The decision framework
Before buying any supplement, ask three questions:
- Do I have a confirmed or likely deficiency? Blood work is ideal. Population-level data (like the vitamin D statistics above) can inform reasonable assumptions.
- Is there strong clinical evidence that supplementation helps? Not a single study. Not animal research. Multiple human RCTs with consistent results. Check our evidence rankings.
- Can I address this through diet instead? If you can get what you need from food, that's almost always the better path. Better absorption, additional co-factors, no pill fatigue.
If you answered yes, yes, and no - supplement. If not, put the money toward better groceries.
The bottom line
We built this site because the supplement industry needs honest scoring, not because everyone needs supplements. The five recommendations in the first section of this article cover the most common real deficiencies. Everything beyond that should be targeted, evidence-based, and ideally confirmed by blood work.
When you do decide to supplement, quality matters. Third-party testing matters. Cost per clinically effective dose matters. That's what we score. But the best supplement decision you can make is knowing when you don't need one at all.