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What dosage of vitamin B12 is typically used for adults?

If you regularly eat animal foods -- fish, chicken, red meat, eggs or dairy -- you may not need to take vitamin B12 supplements at all. Fortified cereals are a good source of the vitamin as well.

Adults need 2.4 micrograms (mcg) of vitamin B12 every day. That's about the amount in three ounces of light tuna fish. Some fortified breakfast cereals have six mcg in each serving.

Some people, especially older adults and people with certain medical conditions, can't absorb B12 well from foods and may require supplements. Vegans, who eat no animal products, sometimes need supplements too.
The government guidelines recommend a daily intake of 2.4 micrograms (mcg) of B12 to prevent deficiency, but for optimal health and disease prevention, we recommend a daily dose of 25 mcg. To get this much -- particularly if you're a strict vegetarian -- you'll probably need to rely on supplements or fortified foods. In fact, B12 may be easier to absorb in supplement form.

If you're over 50 years of age, have acid reflux, or have been told by your doctor that your body has trouble absorbing B12, aim for 400-800 mcg per day to give your body a better chance of absorbing what it needs. Don't worry about overdoing it -- there's no upper limit on B12, which means there's no evidence that high levels (up to 1,000 mcg) are harmful.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.