Why proper vitamin and mineral intake matters
Vitamins and minerals are essential for energy, immunity, and disease prevention, but taking the wrong dose can be harmful.
Many people over-supplement unnecessarily, while others miss key deficiencies.
This guide simplifies science-backed recommendations in an easy-to-scan table, plus:
✔ How to choose supplements safely
✔ Critical interactions to avoid
✔ Best food sources for natural absorption
Key risks of over-supplementation
Before diving into dosages, note:
🔹 Fat-soluble vitamins (A, D, E, K) can accumulate and become toxic.
🔹 Water-soluble vitamins (B, C) are safer but still have limits.
🔹 Minerals like iron and zinc compete for absorption—balance is key.
Always consult a doctor if you:
- Take medications (e.g., blood thinners, thyroid drugs)
- Have kidney/liver issues
- Are pregnant
Table: Complete vitamin/mineral reference chart
| Vitamins ou Minerals | Features | Recommended daily nutritional intake | Precautions |
|---|---|---|---|
| Vitamin A or retinol |
- Antioxidant - Boost immune system - Vision - Skin (scarring, acne, wrinkles) - Iron metabolism |
- Man, 14+: 900µg (3 000IU) - Woman 14+: 700µg (2 330IU) - Pregnant woman: 750µg ( 2 500IU) |
- Safe by oral ingestion or injection up to 10,000IU
- Long-term high dose use may cause side effects
|
| Biotin (B8 or B7) or vitamin H |
- Crucial role in metabolism - Assimilation of vitamins and amino acids - Skin (dermatitis, acne, seborrheic dermatitis) - Strengthens the nails - Hair loss - Anti-fatigue |
- Adult: 50µg - Breastfeeding woman: 55µg - Senior woman: 60µg |
- Safe, excreted in urine - Assimilation blocked by antibiotics and epilepsy treatment
|
| Vitamin B12 |
- Anti-anemic - Vitamin B9 assimilation - Nerve cells protection - Cardiovascular prevention |
- Adult: 2,4µg - Pregnant woman: 2,6µg - Breastfeeding woman: 2,8µg |
- Safe at the recommended dose - Blocked assimilation by potassium supplement - Reduced assimilation by taking antacids, certain antibiotics
|
| Folic acid or vitamin B9 | - Cell renewal (blood cells, skin) - Strengthening the immune system - Prevention of neurological disorders - Cardiovascular prevention (with B12) - Hair loss - Nails (reinforcement) |
- Adult: 400µg |
- Very high dose neurotoxic (do not exceed 1mg per day) - Compromised assimilation by oral contraceptives - Highly recommended for pregnant woman
|
| Vitamin B1 or thiamin |
- Energy production - Nervous system support - Muscle functioning - Alcohol breakdown (withdrawal aid) |
- Adult: 1,4mg | - Safe, excreted in urine - Alcohol inhibits its action - Reduced assimilation by antacids
|
| Vitamin B2 or riboflavin |
- Carbohydrate, lipid, protein metabolism - Energy production - Keratin production - Maintain skin, nails, hair - Vision |
- Adult: 1,5mg - Pregnant woman: 1,6mg - Breastfeeding woman: 1,8mg |
- Safe, excreted in urine - Vitamin B2 deficiency manifests in eye and skin problems
|
| Vitamin B3 or Niacin |
- Energy production - Fight cholesterol - Atherosclerosis prevention - Brain support - Skin - Antifatigue - Healing |
- Man: 16mg - Woman: 14mg - Pregnant woman: 18mg - Breastfeeding woman: 17mg |
- Do not exceed 100mg per day - Medical advice required before supplementation |
| Vitamin B5 or panthotenic acid |
- Fight cholesterol - Nervous system support - Skin regeneration - Mucous membrane protection |
- Adult: 5mg - Pregnant woman: 6mg - Breastfeeding woman: 7mg |
- Safe - Risk of skin irritation when applied - Interaction with statins and antibiotics
|
| Vitamin B6 or Pyridoxine |
- Energy production - Reduce pregnancy nausea - Relief of premenstrual syndrome - Cardiovascular prevention (with B9 and B12) - Psychic balance |
- Adult: 1,3mg - Pregnant woman: 1,9mg - Breastfeeding woman: 2,0mg - Pregnancy nausea: 30mg le matin |
- Do not exceed 100mg per day - Many drugs block the absorption of vitamin B6
|
| Vitamin C |
- Strengthening immune system - Increases iron absorption - Prevention of respiratory diseases (pneumonia) - Cold treatment and prevention - Vision (cataract, macular degeneration) - Prevention of cognitive disorders - Treatment of asthma - Antioxidant |
- Adult: up to 2000mg *Cold prevention: 250mg to 1g per day |
- Safe at the recommended dose Aspirin, anti-inflammatories and oral contraceptives block its absorption
|
| Vitamin D ou Cholecalciferol |
- Osteoporosis prevention - Prevention of certain cancers (bladder, breast, prostate) - Prevention of respiratory infections - Diabetes Type 1 and 2 prevention - Cardiovascular prevention - Strengthening the immune system - Prevention of autoimmune diseases - Psoriasis treatment - Rickets treatment - Tooth decay prevention - Cognitive decline |
- Adult: 600UI - Over 70: 800UI - Maximum daily intake : 4000UI |
- Safe at the recommended dosage - Contraindication: hypocalcemia - Antiepileptics, anticonvulsants, corticosteroids and AIDS treatment block the absorption of vitamin D
|
| Vitamin E or tocopherol |
- Strengthening the immune system - Menstrual problems - Cardiovascular prevention - Cancer prevention - Alzheimer's, Parkinson's prevention - Vision (cataract, macular degeneration) - Arthritis - Diabetes - Antioxidant |
- Adult: 15mg (22,5UI) - Breastfeeding woman: 19mg (28,5UI) Menstrual problems: 200 à 500UI 2 days before period and for 5 days) |
- Safe at the recommended dosage - High dose contraindication with anticoagulants and antiplatelets
|
| Vitamin K |
- Osteoporosis prevention and treatment - Cardiovascular prevention - Infections - Asthma |
- Man: 120µg - Woman: 90µg |
- Safe at the recommended dosage
|
| Calcium |
- Osteoporosis slowdown - Osteoporosis prevention (with vitamin D) - PMS - Cholesterol reduction - Blood pressure reduction - Weightloss |
- Man: 1000mg - Woman: 1200mg - Pregnant woman: 1300mg - Breastfeeding woman: 1300mg |
- Recommended dosage to respect - 2 hours staggered intake with medication: antibiotics, thyroid treatment - Calcium + vitamin D interfere with beta-blockers
|
| Copper | - Metabolism support - Antioxidant - Iron assimilation - Osteoporosis - Strengthening the immune system - Arthritis |
- Adult: 900µg - Pregnant woman: 1000µg - Breastfeeding woman: 1300µg |
- Recommended dosage to respect - Zinc decreases the absorption of copper
|
| Iron | - Energy production - Cell growth regulation - Joint pain - Anti-fatigue |
- Adult: 8mg | - Recommended dosage to respect - Interaction with antibiotics, anti-inflammatories, antacids and calcium
|
| Magnesium | - Cardiovascular prevention - Type 2 diabetes prevention - Migraine relief - Osteoporosis prevention - Cramps relief - Prevention of asthma attacks - PMS relief |
- Man: 420mg - Woman: 320mg - Pregnant woman: 350mg - Breastfeeding woman: 320mg |
- Safe at the recommended dosage - Possible laxative effect depending on the chosen form - Contraindication: kidney disease
|
| Manganese | - Metabolism - Insulin production - Preserves bone mass |
- Man: 2,3mg - Woman: 1,8mg - Pregnant woman: 2mg - Breastfeeding woman: 2,8mg |
- Maximum dose : 11mg/jour
- Calcium and iron decrease its absorption |
| Nickel | - Blood sugar regulation - Anemia treatment - Hypotensor |
- Adult: 75 μg |
- Toxic in excess - Often allergenic - Iron, copper, zinc, vitamin C decrease its absorption |
| Phosphore | - Ensures strong bones and teeth - Osteoporosis prevention - Anti-fatigue - Ensures growth - Maintain blood PH - Trouble concentrating |
- Adult: 700mg |
- Safe at the recommended dosage - Medical advice recommended - Antacids based on aluminum and calcium decrease its absorption |
| Potassium (electrolyte) |
- Essential for muscle contraction - Maintain nerve impulses - Hypokalaemia treatment - Hypertension prevention - Cardiovascular prevention - Stroke prevention - Ostéoporosis prevention - Relieves tooth pain |
- Adult: 4700mg - Pregnant woman: 4700mg - Breastfeeding woman: 5100mg |
- Use under medical supervision |
| Selenium | - Cancer prevention: prostate, colorectal, lungs, skin, bladder - Cardiovascular prevention - Asthma treatment - Hypothyroidism - Antioxidant |
- Adult: 55 µg - Pregnant woman: 60 µg - Breastfeeding woman: 70 µg |
- Safe at the recommended dose - Possible allergic reaction - Not recommended in case of goiter
|
| Sodium (electrolyte) |
- Allows the distribution of water in the body - Blood pressure influence - Provides nerve impulses and muscle contraction |
- Adult: 1300mg - Pregnant woman: 1500mg - Breastfeeding woman: 1500mg |
- Maximum daily intake : 2300mg
- Potassium increases sodium excretion |
| Zinc | - Cold prevention and treatment - Acne treatment - Boosting the immune system - Cardiovascular prevention - Macular degeneration prevention |
- Man: 11mg - Woman: 8mg - Pregnant woman: 12mg - Breastfeeding woman: 13mg - Acne: 30mg |
- Safe at the recommended dosage - Delay taking 2 hours if antacid or antibiotic treatment
|
Practical tips for smarter supplementation
- Test first
- A blood test (vitamin D, B12, iron) prevents guessing.
- Pair nutrients properly
- Vitamin C boosts iron absorption—take together.
- Calcium blocks iron/zinc—space them out.
- Prioritize food sources
- Example: Almonds (magnesium), salmon (vitamin D), spinach (folate).
Related: What is the best form of magnesium supplement?
Smart supplementation: Why balanced nutrition becomes mega-dosing
While vitamins and minerals are essential for health, more isn’t always better—and in some cases, it can be dangerous.
The key takeaways:
✔ Target deficiencies first
- 35% of adults are deficient in vitamin D, while only 2% lack vitamin A (NIH data)
- Blood tests reveal your actual needs instead of guesswork
✔ Food beats pills
- Spinach provides iron + vitamin C for absorption
- Almonds offer magnesium with fiber
- Salmon delivers vitamin D with healthy fats
✔ Synergy matters
- Vitamin D boosts calcium absorption
- Zinc depletes copper over time
- Vitamin C enhances iron uptake
Before you buy another supplement:
- Test – Identify real deficiencies
- Adjust diet – Prioritize nutrient-dense foods
- Supplement smartly – Use precise doses for proven gaps
For personalized natural remedies:
→ 78 Natural Remedies for Common Ailments
FAQ: Your top vitamin questions
What's the best time of day to take vitamins?
The ideal time depends on the vitamin. Water-soluble vitamins like B-complex and vitamin C are best taken in the morning since they provide energy and any excess is flushed out. Minerals like magnesium and calcium are better in the evening as they promote relaxation and bone repair during sleep. Always take fat-soluble vitamins (A, D, E, K) with meals containing healthy fats for proper absorption.
Why do my vitamins make me feel nauseous?
Nausea from vitamins typically comes from three main causes: taking them on an empty stomach (especially iron or zinc), using forms that are harsh on digestion (like magnesium oxide), or sensitivity to certain additives in the supplement. This can usually be resolved by taking vitamins with food, switching to gentler formulations, or dividing doses throughout the day.
Do expired vitamins become dangerous?
While expired water-soluble vitamins like B and C simply lose potency, fat-soluble vitamins (A, D, E) can actually become harmful if they oxidize and go rancid. The oils in these supplements can spoil just like food. As a general rule, you should discard any supplements 2 years after opening them, or by the expiration date if listed.
Why does my urine turn bright yellow after taking vitamins?
That neon yellow color is completely normal and comes from riboflavin (vitamin B2), which your body excretes when it has more than it needs. While it looks alarming, it's harmless and just shows your body is eliminating the excess. If you prefer less intense color, you can reduce your B-vitamin dose slightly.