Vitamin B12 Needs Calculator
Estimate your daily vitamin B12 requirements based on age, diet type, and absorption factors.
Vitamin B12 (cobalamin) is an essential water-soluble vitamin that plays a crucial role in nerve function, red blood cell formation, and DNA synthesis. Unlike most vitamins, B12 is primarily found in animal-based foods, making supplementation important for certain dietary groups.
Recommended Daily Intake (RDI) by age:
- Infants 0-6 months: 0.4 mcg
- Infants 7-12 months: 0.5 mcg
- Children 1-3 years: 0.9 mcg
- Children 4-8 years: 1.2 mcg
- Children 9-13 years: 1.8 mcg
- Teens 14-18 years: 2.4 mcg
- Adults 19+ years: 2.4 mcg
- Pregnant women: 2.6 mcg
- Breastfeeding women: 2.8 mcg
Factors affecting B12 absorption: Your body does not absorb all the B12 you consume. Absorption depends heavily on intrinsic factor, a protein produced in the stomach. Several conditions can reduce absorption significantly.
Diet type matters greatly:
- Omnivores typically get adequate B12 from meat, fish, eggs, and dairy
- Vegetarians may need supplements since they avoid meat and fish
- Vegans almost always need supplementation as plant foods contain virtually no bioavailable B12
- Flexitarians may get enough but should monitor their intake
Age-related absorption decline: Adults over 50 often experience reduced stomach acid production, which impairs B12 absorption from food. Supplemental B12 in crystalline form does not require stomach acid for absorption, making supplements particularly important for older adults.
Signs of B12 deficiency: Fatigue, weakness, numbness or tingling in hands and feet, difficulty walking, mood changes, and cognitive difficulties. Severe deficiency can cause irreversible nerve damage if left untreated.
Food sources ranked by B12 content per serving: Clams (84 mcg), liver (70 mcg), fortified cereals (6 mcg), trout (5.4 mcg), salmon (4.8 mcg), tuna (2.5 mcg), milk (1.2 mcg), yogurt (1.1 mcg), cheese (0.9 mcg), and eggs (0.6 mcg).