Vitamin B Complex Calculator
B12, Folate, B6 and All 8 B Vitamins
Find your exact daily needs for all 8 B vitamins based on your age, gender, pregnancy, and diet. Deficiency risk check, food sources, WhatsApp share, and free PDF report. Based on NIH and EFSA guidelines.
What Are the B Vitamins?
Despite being grouped together as the "B complex," each B vitamin has distinct functions and different risk factors for deficiency. Understanding which B vitamins matter most for your life stage -- pregnancy, older age, vegan diet, or high activity level -- helps you make more targeted nutrition decisions. This calculator uses NIH Office of Dietary Supplements and EFSA (European Food Safety Authority) reference values to generate your personalised requirements. Check your overall nutritional status with our Macro Calculator and Protein Calculator.
Vitamin B12 (Cobalamin) -- The Most Critical to Get Right
Vitamin B12 is arguably the most clinically important of the B vitamins because deficiency is common in specific populations, develops silently over months or years, and can cause serious and sometimes irreversible neurological damage if left untreated. The recommended daily intake is 2.4 mcg for most adults, rising to 2.6 mcg during pregnancy and 2.8 mcg during breastfeeding.
Who Is at Risk of B12 Deficiency?
- Vegans and vegetarians: B12 is found almost exclusively in animal products. Vegans must supplement; many vegetarians also fall short
- Adults over 50: Stomach acid production declines with age. Stomach acid is needed to release B12 from food proteins. People over 50 are advised to get B12 from fortified foods or supplements, which do not require acid for absorption
- People taking metformin: This common diabetes medication reduces B12 absorption
- People with digestive conditions: Crohn's disease, coeliac disease, and gastric bypass surgery all impair B12 absorption
- People taking proton pump inhibitors (PPIs): Acid-reducing medications impair B12 release from food
Symptoms of B12 deficiency include fatigue, weakness, numbness or tingling in hands and feet, balance problems, pale skin, mood changes, and cognitive decline. Because the liver can store B12 for years, deficiency often develops slowly and is missed until significant damage has occurred. Check your blood sugar and cardiovascular markers alongside B12 status -- use our Blood Pressure Checker and Diabetes Risk Score.
Folate (Vitamin B9) -- Critical Before and During Pregnancy
Folate (the natural form found in food) and folic acid (the synthetic form used in supplements and fortified foods) are both forms of vitamin B9. Folate is essential for DNA synthesis, cell division, and amino acid metabolism. The recommended daily intake for most adults is 400 mcg DFE (dietary folate equivalents), rising to 600 mcg DFE during pregnancy.
Adequate folate intake in the weeks before conception and during the first trimester of pregnancy is strongly associated with reduced risk of neural tube defects (spina bifida and anencephaly). Most national health authorities recommend women planning pregnancy take 400-800 mcg of folic acid daily starting at least one month before conception. If you are pregnant, track your due date and trimester with our Pregnancy Calculator and monitor your pregnancy weight gain.
Best Food Sources of Folate
The best dietary sources of folate are dark leafy green vegetables (spinach, kale, asparagus), lentils, chickpeas, black beans, fortified breakfast cereals, avocado, and broccoli. Note that folate is heat-sensitive -- cooking vegetables can reduce their folate content by 50-90%, so raw or lightly steamed is preferable where possible. Track your iron intake alongside folate, as both are critical during pregnancy.
Vitamin B6 (Pyridoxine) -- Energy, Brain, and Immunity
Vitamin B6 is involved in over 100 enzyme reactions in the body, primarily related to protein and amino acid metabolism, neurotransmitter synthesis (including serotonin and dopamine), glycogen breakdown for energy, and immune system function. Adults aged 19-50 need 1.3 mg daily. Requirements rise slightly after age 51 (1.5 mg for women, 1.7 mg for men) and during pregnancy (1.9 mg) and breastfeeding (2.0 mg).
B6 is also widely used to relieve morning sickness during pregnancy, with some research supporting doses of 10-25 mg under medical supervision. Best food sources include chicken, fish, potatoes, bananas, chickpeas, and fortified cereals. B6 toxicity from food is essentially impossible, but high-dose supplementation (above 100 mg daily long-term) can cause peripheral neuropathy.
B1, B2, B3, B5, and B7 -- Quick Reference
| Vitamin | Main Role | Adult RDA | Best Sources | Deficiency Signs |
|---|---|---|---|---|
| B1 Thiamine | Energy from carbs, nerve function | 1.1-1.2 mg/day | Wholegrains, pork, legumes, nuts | Fatigue, nerve problems, heart issues |
| B2 Riboflavin | Energy metabolism, cell growth | 1.1-1.3 mg/day | Dairy, eggs, almonds, lean meat | Cracked lips, sore throat, skin rash |
| B3 Niacin | DNA repair, energy, skin health | 14-16 mg/day | Chicken, tuna, peanuts, mushrooms | Pellagra: dermatitis, diarrhoea |
| B5 Pantothenic Acid | Hormone synthesis, energy metabolism | 5 mg/day (AI) | Beef liver, avocado, sunflower seeds | Rare -- fatigue, numbness |
| B7 Biotin | Fat and carb metabolism, hair/nails | 30 mcg/day (AI) | Eggs, nuts, salmon, sweet potato | Hair loss, skin rash, brittle nails |
Vegans, Vegetarians, and B Vitamins
Plant-based diets are generally nutrient-rich, but B12 is a critical exception. B12 is produced by microorganisms and found almost exclusively in animal products. No plant food reliably provides adequate B12 -- common misconceptions about algae, fermented foods, or nutritional yeast as B12 sources are not supported by evidence.
- Vegans: Must supplement B12. Most nutrition authorities recommend at least 250 mcg daily or 2000 mcg weekly of cyanocobalamin or methylcobalamin
- Vegetarians: Dairy and eggs contain some B12, but many vegetarians still fall below optimal levels. A blood test is the only reliable way to check B12 status
- Both groups: Monitor iron (check our Iron Calculator), calcium (check our Calcium Calculator), vitamin D (check our Vitamin D Calculator), and zinc, which are also less bioavailable on plant-based diets
Signs of B Vitamin Deficiency
- B12 deficiency: Fatigue, weakness, tingling or numbness in hands and feet, pale or yellowish skin, balance problems, memory issues, depression, megaloblastic anaemia
- Folate deficiency: Megaloblastic anaemia, fatigue, mouth sores, neural tube defects in pregnancy
- B6 deficiency: Skin rash, cracked lips, weakened immunity, confusion, depression
- B1 deficiency: Fatigue, irritability, nerve damage, heart problems (more common in heavy alcohol users)
- B2 deficiency: Cracked lips and corners of the mouth, sore throat, swollen tongue, eye sensitivity
- B3 deficiency: Pellagra -- skin rash on sun-exposed areas, diarrhoea, dementia (rare in developed countries)
