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What Strength B12 Supplement Is Right for Me?

author image Sarah Terry
Sarah Terry brings over 10 years of experience writing novels, business-to-business newsletters and a plethora of how-to articles. Terry has written articles and publications for a wide range of markets and subject matters, including Medicine & Health, Eli Financial, Dartnell Publications and Eli Journals.
What Strength B12 Supplement Is Right for Me?
A doctor showing an elderly patient a medicine bottle. Photo Credit 4774344sean/iStock/Getty Images

Also known as cobalamin, vitamin B12 is an essential nutrient that your body needs for the health of your nerves, genetic material, red blood cells and iron metabolism. Your doctor might recommend that you take a vitamin B12 supplement in a specific dose that’s appropriate for your health status. Don’t take vitamin B12 without first talking with your physician, so you can establish a customized dosage and discuss the possible health risks.


Vitamin B12 plays an important role in DNA and RNA replication, as well as supports normal function of your nerve cells, says the University of Michigan Health System (UMHS). Vitamin B12 also regulates your body’s levels of homocysteine, a substance that can influence your risk of heart disease. Coupled with iron, vitamin B12 helps to produce red blood cells, and combined with folate, the vitamin produces the substance S-adenosylmethionine or “SAMe” for mood and immune-system function, explains the University of Maryland Medical Center (UMMC).


Elderly people and vegans, as well as people with malabsorption disorders, ulcer-causing bacterial infections, eating disorders and HIV are all at risk of having a vitamin B12 deficiency, says the UMMC. You might also have a vitamin B12 deficiency if you have anemia, depression, cystic fibrosis, age-related cognitive decline, canker sores, indigestion, sickle cell anemia, dermatitis herpetiformis or phenylketonuria, according to the UMHS. With or without a specific deficiency, vitamin B12 supplements are also sometimes recommended for treating chronic pain, migraines, osteoporosis, type 2 diabetes, cyanide poisoning, Bell’s palsy, chronic fatigue syndrome, asthma, insomnia, bipolar disorder, bursitis and atherosclerosis. Talk to your doctor before taking extra vitamin B12 to treat or prevent any health condition.


If you’re an adult, age 19 years of age or older, the recommended daily allowance of vitamin B12 is 2.4 milligrams (mg), says the UMMC. The daily allowance for pregnant women is 2.6 mg; and for breastfeeding women, 2.8 mg. If you have pernicious anemia, your doctor might recommend that you take 1,000 micrograms (mcg) of vitamin B12 daily or receive injections of the vitamin, notes the UMHS. Elderly people may take 10 to 25 mcg of vitamin B12 each day. Your physician will know the right strength of vitamin B12 that you need to take based on your health conditions and diet.

Dietary Sources

In addition to or in lieu of a supplement, you can also alter your diet to increase your intake of vitamin B12. Steamed clams provide a whopping 84 mcg of vitamin B12, while steamed mussels provide 20.4 mcg, notes the University of Pittsburgh Medical Center. You can also get 60 mcg of vitamin B12 from just 3 ounces of cooked beef liver or 6 mcg from ¾ cup of fortified cereal. Other good sources of vitamin B12 include salmon, beef and rainbow trout. You can also get vitamin B12 in smaller amounts from dairy products like milk, yogurt and cheeses, eggs and chicken.


A B12 deficiency that’s untreated for long periods of time can cause permanent damage to your nerves, warns the University of Pittsburgh Medical Center. Vitamin B12 deficiencies can also increase your risk of heart disease due to elevated blood levels of homocysteine. Sometimes severe allergic reactions to vitamin B12 injections have occurred, notes the UMHS. Also, taking folic acid can hide a B12 deficiency, and taking vitamin B12 could cause an imbalance of other essential B-complex vitamins, says the UMMC. Vitamin B12 supplements could also interfere with certain medications, such as tetracycline antibiotics, anticonvulsants, diabetes and chemotherapy drugs, gout medications such colchicine, and many different types of stomach acid-lowering drugs for acid reflux.

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