Recommended Daily Intake of Vitamins and Minerals
The recommended daily intake of vitamins and minerals varies by nutrient, with specific milligram (mg) requirements established through Dietary Reference Intakes (DRIs) that aim to prevent deficiency while avoiding toxicity. 1
Adult Recommended Daily Allowances (RDAs) for Key Vitamins
- Vitamin B1 (Thiamine): 1.1 mg/day for women, 1.3 mg/day for men 1
- Vitamin B2 (Riboflavin): 1.1 mg/day for women, 1.3 mg/day for men 1
- Vitamin B6: 1.3 mg/day with an upper limit of 100 mg/day 1
- Vitamin B12: 2.4 μg/day 1
- Niacin: 14 mg/day for women, 16 mg/day for men with an upper limit of 35 mg/day 1
- Vitamin C: 75 mg/day for women, 90 mg/day for men with an upper limit of 2,000 mg/day 1
- Vitamin E: 15 mg/day α-tocopherol with an upper limit of 1,000 mg/day 1
- Folic acid: 400 μg/day with an upper limit of 1,000 μg/day from fortified foods and supplements 1
Adult RDAs for Key Minerals
- Calcium: 1,000 mg/day for adults ≤50 years, 1,200 mg/day for adults >50 years with an upper limit of 2,500 mg/day 1
- Iron: 8 mg/day for men and postmenopausal women, 18 mg/day for premenopausal women with an upper limit of 45 mg/day 1
- Magnesium: 320 mg/day for women, 420 mg/day for men with an upper limit of 350 mg/day from supplements 1
- Zinc: 8 mg/day for women, 11 mg/day for men with an upper limit of 40 mg/day 1
- Selenium: 55 μg/day with an upper limit of 400 μg/day 1
Special Considerations for Vitamin Supplementation
Thiamine (Vitamin B1)
- For mild deficiency: 10 mg/day orally for one week, followed by 3-5 mg/day for at least 6 weeks 1, 2
- For maintenance after proven deficiency: 50-100 mg/day orally 1, 2
- For hospitalized patients or critical illness: 100-300 mg/day intravenously 1, 2
- For refeeding syndrome: 300 mg IV before nutrition therapy, then 200-300 mg IV daily for at least 3 days 1, 2
Vitamin D
- For adults: 600 IU/day (15 μg/day) 1
- For infants: 400 IU/day 1
- For children and adolescents: 600 IU/day 1
- Upper limit: 4,000 IU/day for adults and adolescents 9-18 years 1
Vitamin E
- For adults: 15 mg/day α-tocopherol 1
- For infants and children <11 years: ≤11 mg/day 1
- For preterm infants: 2.8-3.5 mg/kg/day, not exceeding 11 mg/day 1
Medication Dosing Principles
- For medications like ibuprofen: Use the lowest effective dose for the shortest duration consistent with treatment goals 3
- For ibuprofen specifically: 1,200-3,200 mg daily (divided doses), not exceeding 3,200 mg total daily dose 3
Factors Affecting Nutrient Requirements
- Individuals with diabetes should be educated about acquiring daily vitamin and mineral requirements from natural food sources 1
- Supplementation with a multivitamin is advisable for elderly individuals, pregnant or lactating women, strict vegetarians, or individuals on calorie-restricted diets 1
- Calcium intakes above normal requirements can decrease magnesium balance 4
- Obesity may increase magnesium requirements due to inflammatory stress 4, 5
- Dietary factors affecting magnesium absorption include protein intake, fiber type, and fructose consumption 4
Potential Risks of Excessive Intake
- Vitamin B6: Sensory neuropathy at doses >100 mg/day 1
- Niacin: Flushing at doses >35 mg/day 1
- Vitamin C: Diarrhea and gastrointestinal disturbances at doses >2,000 mg/day 1
- Vitamin E: Hemorrhage at doses >1,000 mg/day 1
- Iron: Gastrointestinal disturbances at doses >45 mg/day 1
- Zinc: Interference with copper absorption at doses >40 mg/day 1
Special Populations
Bariatric Surgery Patients
- Multivitamin-mineral: Two adult supplements/day containing iron, folic acid, zinc, copper, selenium, and thiamin (200% of the RDA) 1
- Calcium citrate: 600 mg/day (1,200 mg/day after BPD) 1
- Vitamin D: 3,000 IU/day 1
- Iron: 45-60 mg elemental iron/day 1
- Vitamin B12: 250-350 μg/day or 1,000 μg/week sublingual 1
- Thiamin: DRI for thiamin should be included in routine multivitamin 1