Which Supplements Are Actually Worth Taking? An Evidence Review

Walk into any health store and you'll find thousands of supplements promising energy, immunity, longevity, and vitality. The global supplement industry exceeds $150 billion annually.

Most of this money is wasted.

The vast majority of supplements have minimal evidence supporting their use. Many contain less than advertised. Some may be harmful. A few are genuinely useful for specific situations.

Here's an honest assessment of which supplements are worth considering and which aren't worth your money.

The Evidence Problem

Supplements aren't regulated like drugs. They don't need to prove they work before being sold. They only need to not be overtly dangerous.

This means:

• Marketing claims often outpace evidence

• "Studies" cited by manufacturers are often low-quality or industry-funded

• Popular supplements may have no effect whatsoever

• You're trusting manufacturers on quality and dosing

This isn't anti-supplement bias—it's reality. The bar for selling a supplement is dramatically lower than the bar for selling a medication.

Supplements With Good Evidence (For Specific People)

Vitamin D

Who should consider: People with low blood levels, those with limited sun exposure, darker-skinned individuals at northern latitudes

Evidence: Strong for deficiency treatment; moderate for bone health, immunity support

Dose: 1,000-4,000 IU daily depending on deficiency severity

Notes: Test your levels; supplement if low. Many people are deficient. Excessive supplementation unnecessary.

Omega-3 Fatty Acids (Fish Oil)

Who should consider: People who don't eat fish regularly, those with cardiovascular risk factors

Evidence: Moderate for cardiovascular health, inflammation reduction

Dose: 1-2g EPA+DHA daily

Notes: Food sources (fatty fish) are preferable. Quality varies significantly between products.

Vitamin B12

Who should consider: Vegans, vegetarians, adults over 50, those on certain medications (metformin)

Evidence: Strong for deficiency prevention

Dose: 250-500mcg daily for maintenance

Notes: B12 deficiency is serious and common in risk groups. Worth supplementing if you're at risk.

Creatine

Who should consider: Those engaged in strength training or high-intensity exercise

Evidence: Strong for strength and power performance

Dose: 3-5g daily

Notes: One of the most well-researched supplements. Effective for training performance. Safe for long-term use.

Iron

Who should consider: Those with diagnosed deficiency (common in menstruating women)

Evidence: Strong for treating deficiency

Dose: As directed by doctor based on deficiency severity

Notes: Don't supplement without confirming deficiency. Iron excess is harmful. Test before supplementing.

Folate

Who should consider: Women who may become pregnant

Evidence: Strong for preventing neural tube defects

Dose: 400mcg daily (often in prenatal vitamins)

Notes: Important before conception and during early pregnancy

Magnesium

Who should consider: Those with deficiency symptoms, poor dietary intake, high stress

Evidence: Moderate for sleep, stress, muscle function

Dose: 200-400mg daily

Notes: Many people are marginally deficient. Forms like magnesium glycinate are better absorbed.

Supplements With Limited/Mixed Evidence

Multivitamins

Evidence: Most studies show no benefit for people with adequate diets. May fill gaps in poor diets but "insurance policy" concept is overstated.

Bottom line: Probably unnecessary for most. Won't harm, but won't provide meaningful benefit with adequate nutrition.

Probiotics

Evidence: Some strains have evidence for specific conditions (certain digestive issues). General "gut health" benefits are less clear.

Bottom line: Strain-specific and condition-specific. Generic probiotics for general wellness have weak evidence.

Vitamin C

Evidence: Deficiency is serious but rare. For immune support, evidence of benefit in healthy people is minimal except possibly for physically stressed individuals.

Bottom line: Unnecessary for most. Won't prevent colds despite marketing.

Zinc

Evidence: May slightly reduce cold duration if taken immediately at symptom onset.

Bottom line: Possible minor benefit for colds. Unnecessary for general supplementation unless deficient.

Collagen

Evidence: Some evidence for skin and joint health, but studies are often low-quality and industry-funded.

Bottom line: Might help, might not. Better evidence needed.

Supplements With Poor Evidence (Or Overhyped)

Most "immune boosters"

Evidence: Marketing exceeds science. The immune system is complex; simple supplements don't meaningfully "boost" it.

Bottom line: Save your money.

Most "energy" supplements

Evidence: Usually caffeine plus B-vitamins. Caffeine works; B-vitamins only help if deficient.

Bottom line: Just drink coffee.

Most nootropics/"brain boosters"

Evidence: Very limited. Cognitive enhancement claims are largely unsubstantiated.

Bottom line: Overpromised, underdelivered.

Weight loss supplements

Evidence: Most have no effect. Some (ephedra, now banned) worked but were dangerous.

Bottom line: No supplement meaningfully replaces caloric deficit.

Most anti-aging supplements

Evidence: NMN, NAD+ precursors, resveratrol—interesting research but unproven in humans for longevity.

Bottom line: Exciting science, but premature for consumers.

The AI Approach to Supplements

AI helps navigate supplement decisions:

Blood test interpretation.

Your results show low vitamin D. AI recommends appropriate supplementation for your level. Normal D? No supplement needed.

Deficiency risk assessment.

Based on diet, lifestyle, and health factors, AI identifies where you might be at risk of deficiency.

Evidence evaluation.

"I'm thinking of taking X." AI provides honest evidence assessment—not marketing claims.

Interaction awareness.

Some supplements interact with medications or each other. AI helps identify potential issues.

Cost-effectiveness.

Is this expensive supplement worth it? AI helps evaluate bang for buck.

Questions to Ask Before Supplementing

Is there evidence of benefit?

Actual human studies showing meaningful effect, not animal research or theoretical mechanisms.

Am I deficient?

Many supplements only help if you're deficient. Testing confirms whether you need them.

Could I get this from food?

Nutrients from food are generally better absorbed and come with additional beneficial compounds.

What's the quality of this product?

Supplement quality varies. Third-party testing (USP, NSF) provides some assurance.

Is there risk of harm?

Some supplements can be harmful in excess (iron, vitamin A) or interact with medications.

What's the opportunity cost?

Money spent on useless supplements could go toward better food, gym membership, or other health investments.

The Honest Bottom Line

Most people need few or no supplements if they eat reasonably well and address specific deficiencies.

The supplements with best evidence:

• Vitamin D (if deficient—get tested)

• Omega-3s (if you don't eat fish)

• B12 (if vegan/vegetarian or over 50)

• Creatine (if strength training)

• Condition-specific supplements based on diagnosed needs

The vast majority of supplement marketing is just that—marketing. You're not missing out by ignoring most products.

Focus on food, sleep, exercise, and stress management. These matter more than any supplement, and they're not for sale in pill form.

Frequently Asked Questions

Should I take a multivitamin?

Probably not necessary if you eat a varied diet. They're unlikely to harm but unlikely to help meaningfully either.

Are supplements regulated?

Minimally. They don't require efficacy proof before sale. Quality control varies. Look for third-party testing certifications.

How do I know if I need a supplement?

Blood testing identifies deficiencies. Without testing, you're guessing. Ask your GP for relevant tests based on your risk factors.

Are expensive supplements better?

Not necessarily. Price doesn't guarantee quality or effectiveness. Third-party testing matters more than price.

Can supplements replace a good diet?

No. Supplements provide isolated nutrients. Food provides nutrients plus fiber, phytochemicals, and other beneficial compounds that supplements can't replicate.

Are there any supplements that are dangerous?

Yes. Iron (if not deficient), vitamin A (in excess), and some herbal supplements can be harmful. More isn't better, and some interactions are dangerous.