The last mile, not the first
Most people overestimate what supplements add and underestimate what a good diet already delivers. Major guideline bodies — from the USPSTF to the European Society of Cardiology — consistently conclude that supplements rarely outperform a solid dietary pattern in a healthy adult without deficiency.1,3
That said, a few situations are where supplements measurably help: confirmed deficiencies, specific life stages (pregnancy, perimenopause, older adults), particular diets (vegetarian, vegan) and athletic performance. The trick is separating those few exceptions from the marketing-driven default of 'everyone needs a multi'.
Proven deficiency interventions
Four supplements have strong evidence when deficiency is documented:
- Vitamin D — widespread shortfall in Northern Europe, especially in winter; supplementation is cheap, safe and effective when 25-OH is measured low (< 50 nmol/L).
- Vitamin B12 — essential for vegetarians/vegans, older adults and users of metformin or proton-pump inhibitors; MMA is a more sensitive confirmation when borderline.4
- Iron — for women with heavy menstrual bleeding, vegetarians and athletes; ferritin is the most sensitive early marker and belongs on the first panel for fatigue complaints.5
- Folate — recommended throughout pregnancy (and ideally pre-conception) by every national guideline.
In all of these: measure, supplement, re-measure after 3-6 months. Don't blind-dose. The Optimize Baseline measures B12, folate, vitamin D and ferritin by default.
Conditional use cases
Four supplements with evidence in specific situations:
- Omega-3 (EPA/DHA) — worthwhile when fish intake is low (< 2× per week); the large VITAL trial showed modest cardiovascular benefit in specific subgroups, with a stronger signal in those with elevated triglycerides.2 The omega-3 index in blood (4–8% is suboptimal, > 8% optimal) is the relevant marker.
- Creatine monohydrate — one of the best-supported sports supplements, with measurable gains in strength, muscle mass and even cognitive performance under sleep restriction. 3-5 g per day, no 'loading phase' required; cheap and well-studied.6
- Protein supplementation (whey/casein/pea) — useful when daily protein intake falls short (see the Nutrition guide for 1.2-1.6 g/kg/day), not magical.
- Magnesium — measurable effects in confirmed deficiency and in disturbed sleep; pick a well-absorbed form (glycinate or citrate) over oxide.
What doesn't hold up
Three categories that don't deliver what the marketing promises:
- Multivitamins for healthy adults — meta-analyses consistently show no effect on cardiovascular disease, cancer or all-cause mortality.1 For specific groups (pregnancy, older adults with documented deficiency) a targeted multi can be useful, but the default 'everyone takes a multi' isn't grounded in evidence.
- Megadosing — past a threshold, more rarely becomes better and sometimes becomes worse. Vitamin D above 4000 IU/day long-term without monitoring, iron megadoses without deficiency, or vitamin E megadoses provide no extra benefit while introducing risk.
- Nootropics, novelty and detox supplements — the evidence is generally thin, often manufacturer-funded, and rarely independently replicable. No rigorous evidence for meaningful liver or kidney 'cleansing' in healthy adults.
Measurement as the lever
The difference between guessing and targeted supplementation lives in measurement. Before taking a vitamin, it's almost always more useful to measure the marker first: vitamin D status, B12 (with MMA when borderline), ferritin, folate, omega-3 index. The Optimize Baseline measures the first four by default; omega-3 index is an add-on.
On quality: in Europe nutritional supplements are regulated differently than medication — quality varies widely. Choose brands with external lab verification (NSF, USP, Informed-Sport for athletes) and watch for heavy-metal contamination in cheaper fish oil and plant extracts. Many supplements also interact with prescription drugs (anticoagulants, antihypertensives, thyroid medication) — discuss new supplements with your physician if you take prescribed meds.
What you can do yourself
The order that holds up in research: lifestyle first (sleep, exercise, nutrition, stress, social connection), then measurement, then targeted addition. A supplement is a targeted answer to a measured problem — not a daily insurance policy.
Practical steps before supplementing: look first at what your diet doesn't provide (vegetarian → watch B12 + iron; little fish → consider omega-3; winter at northern latitudes → check vitamin D). Then a Baseline measurement for the relevant markers. And keep the stack small — four to six targeted, evidence-backed products is plenty for most people.
When to involve a physician or dietitian
Book a GP or dietitian when complaints persist despite resolving deficiencies (something else may be at play), when you're combining multiple supplements with prescription medication (interactions), when considering high doses (vit D > 4000 IU, iron > 50 mg, vit B6 > 100 mg), or in specific life stages where bespoke advice matters (pregnancy, perimenopause, post-bariatric surgery). At Optimize every result is reviewed by our physician with marker-specific guidance — including when a supplement makes sense and when it doesn't.