From the FDA Drug Label
DOSAGE AND ADMINISTRATION Oral administration is preferred. Although most patients with malabsorption cannot absorb food folates, they are able to absorb folic acid given orally. Pernicious Anemia Parenteral Vitamin B12 is the recommended treatment and will be required for the remainder of the patient's life. The oral form is not dependable A dose of 100 mcg daily for six or seven days should be administered by intramuscular or deep subcutaneous injection. Chronic treatment should be with an oral B12 preparation
The optimal forms and timing of vitamin B12 and folate (B9) supplements are:
- Vitamin B12: 100 mcg daily for six or seven days by intramuscular or deep subcutaneous injection, followed by 100 mcg monthly for life in patients with pernicious anemia. For patients with normal intestinal absorption, chronic treatment should be with an oral B12 preparation.
- Folate (B9): up to 1 mg daily, with a maintenance level of 0.1 mg for infants, up to 0.3 mg for children under 4 years, 0.4 mg for adults and children 4 or more years, and 0.8 mg for pregnant and lactating women. There is no information in the provided drug labels about calcium, magnesium, vitamin D, and iron supplements. 1 2
From the Research
For optimal supplementation of key nutrients, I recommend specific forms and timing strategies to maximize absorption and prevent deficiencies. To achieve this, it's crucial to consider the most recent and highest quality studies.
Key Nutrient Supplementation Strategies
- For B12, methylcobalamin or adenosylcobalamin (500-1000mcg daily) are highly bioavailable forms best taken in the morning on an empty stomach, as suggested by general medical knowledge and supported by studies on nutrient absorption 3.
- For B9 (folate), choose methylfolate (400-800mcg daily) rather than folic acid, as it's more readily used by the body, especially for those with MTHFR gene variants, and take it with breakfast.
- Calcium is best absorbed as calcium citrate (500mg twice daily) since it doesn't require stomach acid for absorption, unlike calcium carbonate. Take it between meals with vitamin D for enhanced absorption, but separate from iron supplements by at least 2 hours.
- For magnesium, magnesium glycinate or malate (300-400mg daily) offer excellent bioavailability with minimal digestive discomfort. Take in the evening, as it can promote relaxation and sleep.
- Vitamin D3 (cholecalciferol, 1000-4000 IU daily) is superior to D2 and should be taken with a fatty meal to enhance absorption, as shown in a study on vitamin D absorption 4.
- For iron, ferrous bisglycinate (25-50mg elemental iron daily) causes less gastrointestinal distress than ferrous sulfate and has better absorption. Take iron on an empty stomach with vitamin C (like orange juice) to enhance absorption, but avoid taking with calcium, dairy, coffee, tea, or high-fiber foods, which inhibit absorption, as demonstrated by a study on iron absorption 5. If stomach upset occurs, take with a small amount of food.
Timing and Dosing Considerations
- Iron supplements should be taken in the morning, away from meals or coffee, and with an AA-rich food or beverage to maximize efficacy, as suggested by a recent study on iron absorption timing 5.
- Alternate-day dosing of oral iron supplements may be preferable because it sharply increases fractional iron absorption (FIA), as found in a study on iron dosing strategies 6.
- Providing lower dosages (40-80 mg Fe) and avoiding twice-daily dosing can maximize fractional absorption, as indicated by research on iron supplementation 7.
By following these specific forms and timing strategies, patients can maximize absorption while minimizing potential side effects or nutrient interactions, ultimately reducing the risk of deficiencies and improving overall health outcomes.