Health Reference LibraryWhat supplements should I take? A three-tier answer
This entry is part of the Nutri Tailor Health Reference Library — cited research on supplements, nutrients and adjacent areas of health.
Summary
Three tiers apply in order. The baseline covers nearly everyone in the UK, meaning vitamin D at 10 micrograms a day October to March, year-round with little sun or darker skin, per the NHS, folic acid at 400 micrograms for anyone who could become pregnant, and B12 for vegans. The tested tier runs ferritin, B12, vitamin D and TSH, because they are cheap tests and correcting a measured low beats any guess, with each result read on its hub. The goal tier runs one evidenced supplement per named situation, one at a time, judged at four to twelve weeks. Nobody needs twelve bottles.
Free blood test result interpreter
Paste your results once and every recognised value is picked out for you to check. Nothing you enter leaves this device. Nothing is saved. No AI is used, only published UK guideline thresholds.
How it works
Supplements work by correcting a shortfall or serving a mechanism, and both are personal. A nutrient you are replete in does nothing at the margin, which is why multivitamin trials in well-fed populations keep coming back flat, and why the same iron that transforms a depleted runner does nothing for a replete one and harms someone with haemochromatosis. The UK baseline exists because sunlight, not diet, is the vitamin D source and the UK winter sun is too weak; because neural tube development happens before most pregnancies are known; and because B12 does not occur in plants. Everything beyond the baseline is either measured, ferritin, B12, D, TSH, or situational, where a specific trial base supports a specific use.
Timing
Vitamin D starts in October. Folic acid starts before conception. Test-tier corrections are judged at twelve weeks with a re-test. Goal-tier trials run four to twelve weeks each, one at a time.
Safety profile
More is not better: vitamin D above 100 micrograms a day, iron without a low result, B6 above the guidance, and high-dose iodine all carry real harms covered on their pages. Supplements interact with prescriptions, thyroid hormone timing, blood thinners, diabetes prescriptions among them, which is why the check comes before the purchase. Anyone pregnant, breastfeeding, under 18 or managing a diagnosed condition starts with the GP or pharmacist. Nutri365 checks for interactions and contraindications before suggesting anything.
Special populations
Vegans: B12 always, iodine and omega-3 reviewed. Over-65s: vitamin D year-round, B12 absorption falls with age, protein rises in priority. Menstruating women and endurance athletes: ferritin is the test that pays. Pregnant and planning: folic acid plus vitamin D, and everything else through the midwife or GP. On metformin or a proton pump inhibitor long-term: B12 checked.
Guideline positions
NHS: everyone should consider 10 micrograms of vitamin D daily in autumn and winter, and year-round for people seldom outdoors, in care settings, usually covered up, or with darker skin; adults need around 700 mg of calcium from diet; 400 micrograms of folic acid daily for anyone who could become pregnant, until 12 weeks of pregnancy. NHS vegan guidance: reliable B12 source required. The testing thresholds live on the hubs: [ferritin](/apps/learn/ferritin-blood-test-results-explained-uk-what-your-number-means), [B12](/apps/learn/b12-blood-test-results-explained-uk-what-your-number-means), [vitamin D](/apps/learn/vitamin-d-blood-test-results-explained-uk-what-your-number-means), [TSH](/apps/learn/tsh-blood-test-results-explained-uk-what-your-number-means).
Practical framework
Tier one is taken without testing, meaning vitamin D at 10 micrograms through the winter, or all year where the sun rarely reaches, with the D3 and K2 form question on the [vitamin D hub](/apps/learn/vitamin-d-blood-test-results-explained-uk-what-your-number-means), folic acid at 400 micrograms where pregnancy is possible, and B12 for vegans. Tier two tests then corrects, with the fatigue panel, meaning ferritin, full blood count, B12, folate, vitamin D, TSH and HbA1c, especially where tiredness, shedding hair, low mood or hard training fits, with the method on [supplements for fatigue](/apps/learn/supplements-for-fatigue-what-the-evidence-supports). Tier three runs one goal, one supplement, one fair trial: [sleep](/apps/learn/supplements-for-sleep-what-the-evidence-supports), [anxiety and stress](/apps/learn/supplements-for-anxiety-what-the-evidence-supports), [joint pain](/apps/learn/supplements-for-joint-pain-what-the-evidence-supports), [hair](/apps/learn/supplements-for-hair-loss-what-the-evidence-supports), [PMS](/apps/learn/supplements-for-pms-what-the-evidence-supports), [immune](/apps/learn/immune-supplements-what-the-evidence-supports), [blood sugar](/apps/learn/supplements-for-blood-sugar-what-the-evidence-supports), and [weight](/apps/learn/supplements-for-weight-loss-what-the-evidence-supports). One thing is added at a time, given its trial window, and judged on the symptom it was for. Nutri365 runs this whole method continuously as results and seasons change, checks everything else taken for interactions and contraindications, and refers questions outside scope to a health specialist.
Common misconceptions
A multivitamin is not a diet insurance policy with evidence behind it, because the trials in well-fed adults are flat. Expensive urine is real. More capsules do not mean more health, and twelve bottles usually mean none of them is being judged. Greens powders are not vegetables. The best supplement decision most people can make this year is a blood test.
Sources
- 2024. Vitamin D. NHS.
- 2024. B vitamins and folic acid. NHS.
- 2024. Calcium. NHS.