Tag Archives: Dietary Reference Intake

The In’s & Out’s of Vitamin B-12 Deficiency

A severe B12 (cobalamin) deficiency will eventually result in anemia if uncorrected. Anemia refers to an insufficient number of healthy red blood cells, which impairs the ability of oxygen to be carried to your body’s tissues. Pernicious anemia – the type caused specifically by cobalamin deficiency – can gravely impair neurologic function. Subclinical deficiency is much more common, in which a low cobalamin level appears on a blood test, but has yet to cause anemia.

Recall from my previous post on vegetarian diets that absorption of vitamin B12 is dependent on intrinsic factor (IF), which is produced in the gut.  Causes of deficiency include inadequate dietary intake and impaired intestinal malabsorption, possibly due to lack of IF or insufficient  gastric acid secretion (as is the case in the elderly). If your blood labs do not improve after dietary manipulation or supplementation, speak with your doctor about other tests that can determine if your deficiency is related to malabsorption.

The severity of your B12 deficiency dictates the level of supplementation required. A B12 level less than 400 pg/mL may be cause for concern, but it’s all about lab value trends. Correction of vitamin B12 levels to within the acceptable range may simply require a daily multivitamin (that usually contains 6 µg per tablet). The recommended daily intake for American adults is 2.4 µg. Research shows that for people (like vegetarians) who have normal B12 absorption, doses greater than 5 µg per day exceed the binding capacity of IF and only a tiny fraction can be absorbed anyway.

On the other hand, a more critical deficiency may require several weeks of high-dose supplementation (e.g. 1,000 µg daily oral dose) to be taken under the direction of your doctor. Sublingual B12 supplements, which dissolve under your tongue, are very effective in delivering the nutrient directly to your bloodstream, similar to an injection. These oral supplements come in 1,000 or even 5,000 µg doses or more! “Mega-dosing,” however, is excessive for someone who is still only moderately low in B12. While no toxic level of B12 supplementation has been found to date, it’s always wise to stick with the lowest dose possible that will effectively achieve healthful results.

Leave a comment

Filed under Medical Conditions, Supplements, Vitamins & Minerals

Planning A Vegetarian diet

The quality of any diet – inclusive of meat or not – depends on whether nutritionally-sound food choices are made. The term ‘vegetarian’ refers to people who steer clear of most or all animal-derived foods, including eggs and dairy. Lacto-ovo vegetarians, on the other hand, consume milk products and eggs, but exclude meat and seafood. Ovo-vegetarians include eggs, but do not eat meat, seafood or dairy. Lastly, pesco-vegetarians eat seafood, eggs and dairy, but not meat or poultry. Depending on what type of “vegetarian” you are, a carefully planned diet must include good sources of calcium, iron, zinc and B12:

Calcium: If you don’t eat dairy products, you should select calcium-fortified juices, soy milk and breakfast cereals. Other good sources of absorbable calcium include figs, fortified tofu, some beans, and certain green vegetables, such as broccoli, kale and turnip greens.

Iron: The iron in plant foods, such as beans, dark green leafy vegetables and whole-grain breads is poorly absorbed.Luckily, vegetarians tend to eat produce that’s rich in vitamin C, which helps the body absorb iron more efficiently.

Zinc: Meat is the richest source of bioavailable zinc. Since soy interferes with zinc absorption, it’s important to include whole grains, nuts, and beans such as black-eyed peas, pinto beans and kidney beans in your diet.

B12: This vitamin, also known as cyanocobalamin, is only found in animal products. While soy products may contain some B12, it is not in the active form. The recommended daily intake for male and female adults is 2.4µg/day, although percent daily values (% DV) on food labels are based on 6µg. Your body stores about 5 years of B12, after which a deficiency in this vitamin can be extremely detrimental to your health. Strict vegetarians should not ignore this nutrient. B12 is absorbed with the help of intrinsic factor (IF), which is produced in your stomach. If you’re 60 or older, the loss of IF and low stomach acid levels may lead to B12 deficiency, whether or not you adhere to a vegetarian diet. If the deficiency is due to the loss of IF, you may need an intramuscular B12 injection.  If you’re younger, low B12 levels are more likely due to inadequate dietary intake and an oral vitamin supplement and careful food planning will help. Depending on what type of vegetarian you are, non-meat sources high in B12 include mollusks (e.g. clams), salmon, trout, tuna, egg, yogurt, American cheese and fortified cereal.

2 Comments

Filed under Food Groups, Meal Tips, Vitamins & Minerals