Supplements & Nutrients (Human)

Start with the question 'do I actually need this?' before the question 'which brand?' Most supplement use happens without baseline testing — meaning people supplement what they think they need rather than what testing would show.

First synthesised Mar 25, 2026·Last reviewed Mar 25, 2026·1341 min of expert content·Built from 21 expert discussions

The Health Path

The sequence experts consistently converge on.

1

Test before you supplement — and only supplement what you actually need

Most supplement use happens without baseline testing. Vitamin D, B12, ferritin (iron stores), magnesium status, and the omega-3 index can be checked through standard labs. Test, correct deficiency if found, retest at 3 to 6 months. Megadose protocols without testing produce a small risk of toxicity and a larger certainty of wasted money. Healthy adults with a varied diet, regular sunlight exposure, and no specific symptoms may have very little to supplement at all. Start with the question 'do I actually need this?' before the question 'which brand?'

2

Vitamin D — correct deficiency, don't pursue 'optimal' upper-range levels

Vitamin D deficiency is genuinely common — particularly in northern latitudes, in people with limited outdoor exposure, and in darker-s…

What influences the path

Each step in the full Health Path is strengthened by five additional evidence layers:

  • Benefits from other Health Areas
  • Mistakes to avoid
  • Context that changes the advice
  • Where experts disagree
  • What's changing now
Continue the Health Path

See all 6 steps in order, the reasoning behind each, and how this area connects to every other Health Area.