Q: I don’t eat meat or dairy. Should I take a B12 supplement?
Meat-eater or not, you need to pay attention to vitamin B12. The nutrient helps make DNA and red blood cells, which carry oxygen to all parts of the body, and is crucial for nerve and brain function.
Even if you do eat meat (a good source of B12), you could still run short on the vitamin if you don’t consume enough of it, if you can’t absorb it properly or if you take certain medications. And if you’re over 60, a low B12 level is relatively common.
What foods are high in vitamin B12?
Healthy adults and teens need 2.4 mcg of vitamin B12 each day. Children aged 9 to 13 require 1.8 mcg and younger children need 0.9 to 1.2 mcg depending on age.
B12 is found naturally only in animal foods – meat, poultry, fish, dairy products and eggs. Excellent sources include mussels (20 mcg per 3 ounces), mackerel (16 mcg per 3 ounces), trout (6.7 mcg per 3 ounces) and beef (3 mcg per 3 ounces). One cup of milk has 1.2 mcg and one large egg supplies 0.4 mcg.
Foods fortified with B12 include ready-to-eat breakfast cereals, plant-based “milks,” soy “meats” and some brands of nutritional yeast.
What are the side effects of a vitamin B12 deficiency?
A mild deficiency may cause no symptoms, but if untreated it could lead to megaloblastic anemia, an anemia that occurs when red blood cells don’t develop properly. Symptoms include fatigue, weakness, shortness of breath and fast heart rate.
A lack of B12 can also affect the nervous system, causing numbness and tingling in the hands and feet, muscle weakness and problems walking. Mood changes, poor memory and difficulty thinking may also occur.
B12 deficiency can damage the nervous system even in people who don’t have anemia, so it’s important to get treated as soon as possible. A deficiency that occurs for years can cause irreversible nerve damage.
If you’re concerned you may be B12 deficient, consult your doctor.
Who is at risk of B12 deficiency?
The main causes of B12 deficiency include poor B12 absorption from food, low dietary intake and pernicious anemia, an autoimmune condition that makes it hard for the body to absorb B12 from foods and supplements.
Some groups of people are at greater risk of B12 deficiency than others.
Up to 30 per cent of adults over 60 are thought to have atrophic gastritis, a condition in which the stomach doesn’t produce enough hydrochloric acid. Hydrochloric acid is key for B12 absorption; it’s needed to cleave the vitamin from proteins in food.
Vegans are at risk since they don’t eat animal foods. But even vegetarians who eat fish, dairy and/or eggs may be at risk if they don’t eat these foods regularly.
Medications used to treat acid reflux and ulcers, such as proton pump inhibitors (e.g., Losec, Nexium, Prevacid) and H2 blockers (e.g., Tagamet, Zantac, Pepcid), interfere with B12 absorption by reducing the stomach’s production of hydrochloric acid.
The medication metformin, used to control blood sugar, interferes with B12′s absorption in the small intestine. Numerous studies have linked long-term metformin use to depleted B12 levels.
Digestive conditions such as celiac disease and Crohn’s disease, heavy alcohol use and weight loss surgery (e.g., gastric bypass) may also cause B12 deficiency.
How to prevent and treat a B12 deficiency
To prevent a B12 deficiency, include a variety of animal foods in your regular diet. If you’re over 50, it’s recommended that you get most of your daily B12 from a supplement (e.g., multivitamin, B complex) or fortified foods.
Vegans should include B12-fortified foods in their diet and take a daily supplement supplying 250 mcg (0.25 mg) of B12, an amount found in higher dose B complex supplements. Other vegetarians should supplement with 250 mcg of B12 a few times a week.
Long-term users of acid-blocking medication or metformin should also take a B12 supplement.
If your doctor identifies a B12 deficiency, a supplement of 1000 mcg B12 will be recommended to replenish stores. In some cases, B12 injections are required.
Vitamin B12 is water-soluble and is generally considered safe, even at high doses.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD
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