Why micronutrients matter
Macronutrients fuel the body. Micronutrients regulate the systems that use them. Deficiencies cause fatigue, poor recovery, mood issues, and chronic disease — even when calories and macros are right.
The major vitamins
Fat-soluble (stored in body):- Vitamin A — vision, skin, immunity. Sources: liver, eggs, dairy, leafy greens (beta-carotene).
- Vitamin D — bone health, immunity, mood. Sources: sun, fatty fish, fortified dairy. Most people are deficient.
- Vitamin E — antioxidant. Sources: nuts, seeds, oils.
- Vitamin K — blood clotting, bone health. Sources: leafy greens.
- B vitamins (thiamin, riboflavin, niacin, B6, B12, folate, etc.) — energy metabolism. Sources: whole grains, meat, eggs, dairy, leafy greens.
- Vitamin C — collagen synthesis, immune function. Sources: citrus, berries, peppers, broccoli.
The major minerals
Macrominerals:- Calcium — bones, muscle contraction. Sources: dairy, leafy greens, fortified foods.
- Phosphorus — bones, ATP. Sources: protein-rich foods.
- Magnesium — 300+ enzymatic reactions, sleep, muscle relaxation. Sources: leafy greens, nuts, seeds, whole grains.
- Sodium, potassium, chloride — electrolytes.
- Sulfur — protein structure.
Common deficiencies in modern populations
Vitamin D — most adults indoors most days are insufficient. Get tested. Supplement if low. Iron — common in menstruating women, vegetarians, endurance athletes. Symptoms: fatigue, pale skin, hair loss, poor recovery. Get tested before supplementing — too much iron is also harmful. Magnesium — most adults under-consume. Symptoms: poor sleep, muscle cramps, irritability. Omega-3 fatty acids — most diets are heavy in omega-6, light in omega-3. Sources: fatty fish 2-3×/week or a quality fish oil supplement. B12 — common in vegans/vegetarians. Animal foods are the only reliable natural source. Iodine — common in those who don't use iodized salt and don't eat seafood or dairy.How to assess
For most clients, food-first works. If symptoms suggest deficiency, recommend a blood panel through their doctor:
- Vitamin D, B12, iron studies (ferritin, transferrin saturation), magnesium
Food-first vs supplementation
A varied diet covers most micronutrients:
- Leafy greens daily
- Protein at each meal
- Fruit and vegetables daily
- Whole grains, nuts, seeds, dairy (if tolerated)
- Fatty fish 2-3×/week
- Vitamin D (most adults)
- Omega-3 (if not eating fatty fish)
- A basic multivitamin (insurance, not substitute)
- Magnesium (if symptoms suggest deficit)
What NOT to do
- Don't recommend megadoses (fat-soluble vitamins build up to toxic levels)
- Don't prescribe supplements as a trainer — recommend with physician confirmation
- Don't trust "tests" sold by supplement companies — go through a real medical lab
TL;DR
Vitamins (fat- vs water-soluble) and minerals regulate every body system. Common deficiencies: vitamin D, iron, magnesium, omega-3, B12. Food first; supplements as insurance or for confirmed deficiency. Recommend physician testing — don't diagnose.