Vitamin B12

• Making red blood cells. Deficiency can cause anaemia and tiredness. Extra B12 is not an all-purpose energy pill if you have enough already. [1] [3]
• Keeping nerves working. Longstanding shortage may cause tingling, walking or memory problems, even without anaemia; delaying treatment can leave lasting harm. [3]
• Preventing deficiency on a vegan diet. Use reliable fortified food over the day and a suitable B12 supplement; seaweed is not a dependable substitute. [1]

Meat, fish, dairy and eggs supply B12; some foods have B12 added. Vegetables, fruit and grains without added B12 are not dependable sources. Some algae or seaweed contain B12-like substances the body may not be able to use. Check labels on plant milks and meat substitutes instead of assuming all plant products contain useful B12. [1][2]

Voedingscentrum advises vegans to use foods with added B12 across the day as well as a B12 supplement. If all your B12 comes from one tablet or one sitting, you may need a different amount because the body absorbs less at once. Ask for personal food advice instead of assuming one tablet matching the daily food guideline is enough. [1]

Dutch daily food advice is 2.8 micrograms for adults, 3.3 micrograms during pregnancy and 3.8 micrograms while breastfeeding. These are food amounts, not treatment doses for a confirmed shortage. Children need different amounts. [1]

The NHS lists about 1.5 micrograms for UK adults aged 19–64. That UK advice does not replace Dutch advice for vegans. People eating animal foods usually do not need extra B12 unless intake or absorption is limited for another reason. [1][2]

A stomach protein called intrinsic factor helps you absorb B12 from food. Stomach or bowel problems, pernicious anaemia or some medicines can interfere, even with a varied diet. Absorption difficulties may become more common with age. [1] [3]

If you have symptoms, a long vegan diet without supplements or a possible absorption problem, discuss food and medicines with a clinician. Do not stop prescriptions on your own; confirmed deficiency may need treatment-strength tablets or injections. [3]

Tiredness and anaemia can occur, but tingling, difficulty walking or memory changes may appear without anaemia. Have persistent or new nerve symptoms checked promptly: delayed care cannot always reverse the damage. [3]

A clinician weighs symptoms, diet, medicines and blood tests, then decides if high-dose tablets or injections are needed. Animal foods alone may not be enough when absorption is impaired. [1] [3]

Voedingscentrum reports no established upper limit for B12 and no known harm from high intakes; that is not a reason for a megadose without indication. Its general advice does not recommend routine extra B12 for people with adequate diets, while vegans have a specific supplementation recommendation.[1]

Treatment doses or injections for confirmed deficiency are different from a daily nutritional target. High folic acid intake can mask B12 deficiency while nerve damage continues. Tell your clinician about existing supplements, and seek timely assessment for persistent tingling, changes in walking or memory problems.[2][3]