The Vitamins and Minerals Most People Actually Fall Short On
Where some of the most settled nutrition science exists
Vitamins and minerals supply no energy, but their absence or shortage is where some of the most measurable, least controversial nutrition science exists. Deficiency diseases — scurvy (a vitamin C deficiency causing bleeding gums and fatigue), rickets (a vitamin D deficiency causing softened, weakened bones), goitre (an enlarged thyroid gland, from iodine deficiency), and pellagra (a niacin/vitamin B3 deficiency causing skin, gut, and neurological symptoms) — were largely solved by twentieth-century nutrition science and remain rare in food-secure populations, but suboptimal intake — short of overt deficiency — is still common.
The nutrients worth paying specific attention to
| Nutrient | Why it matters | At-risk groups |
|---|---|---|
| Vitamin D | Bone health, immune function; synthesised via sunlight exposure on skin. Low levels can show up as fatigue and bone or muscle aches | Anyone with limited sun exposure, darker skin tones, northern latitudes in winter[39][40] |
| Iron | Oxygen transport via haemoglobin (the protein in red blood cells that carries oxygen); deficiency causes fatigue and anaemia | Menstruating women, vegetarians/vegans, endurance athletes |
| Calcium | Bone mineralisation, muscle and nerve function. Deficiency is usually silent until bone density loss shows up later | Low dairy intake, post-menopausal women[40] |
| Iodine | Thyroid hormone production. Low intake can cause visible neck swelling (goitre) | Those avoiding iodised salt, dairy, and seafood |
| Vitamin B12 | Nerve function, red blood cell formation. Deficiency can cause tingling or numbness, brain fog, and fatigue | Vegans and vegetarians (plant foods contain negligible B12) |
| Folate | DNA synthesis; critical pre-conception and in early pregnancy. Low levels can cause fatigue and mouth sores | Women planning pregnancy or in the first trimester |
| Magnesium | Muscle and nerve function, energy metabolism. Low levels often show up as cramps or muscle twitches | Diets low in vegetables, legumes, nuts, and whole grains |
| Potassium | Blood pressure regulation, fluid balance. Low levels can cause muscle weakness or heart palpitations | Diets low in fruit and vegetables, high in processed food[41] |
Sodium: more nuanced than “just eat less salt”
Too much salt is linked to higher blood pressure, and most high-income countries eat well above the recommended limit — mostly from processed and restaurant food, not the salt shaker at home[42]. People also vary a lot in how sensitive they are to salt. And it's not just individual variation: a large study (PURE) found that both very low and very high sodium intake were linked to higher heart risk than the middle ground, and the same researchers argue current sodium targets are stricter than the evidence justifies for people without high blood pressure[43]. Experts are genuinely split on this one — but for most people, just cooking from scratch more often brings sodium to a sensible level without needing to track it.
Science Verdict
Recommendation: Cook more from scratch and rely less on processed/restaurant food, and sodium takes care of itself for most people. Don't obsess over exact mg targets unless you have hypertension or another doctor-flagged reason to.
Evidence strength: Moderate
Experts genuinely disagree on how strict population-wide targets should be — see above.
Do you need a multivitamin?
If you eat a varied diet with enough calories, a daily multivitamin hasn't been shown to meaningfully cut disease risk or improve outcomes in large trials — think of it as insurance against minor gaps, not a performance or longevity boost. It makes more sense in specific situations: a restrictive diet, pregnancy, older age, or limited variety in what you eat. It's not a fix for an otherwise poor diet.
A simple test for micronutrient adequacy
If your plate regularly includes a variety of colours from vegetables and fruit, a protein source, and is not overwhelmingly built from refined, processed foods, overt micronutrient deficiency is unlikely. The exceptions in the table above — particularly vitamin D, B12, and iron for specific groups — are worth deliberately checking rather than assuming variety alone covers them.
What this means in practice
Eat a variety of colours of vegetables and fruit daily — this single habit covers most micronutrient bases without supplements.
If you're vegan/vegetarian, pregnant, over 65, or eat a restricted diet, get vitamin D, B12, and iron specifically checked rather than guessing.
A multivitamin is a reasonable insurance policy in those specific situations — not a substitute for fixing the underlying diet.