VITAMIN B12—ARE YOU GETTING ENOUGH?
I keep reading that most vitamin supplements aren’t necessary if one is eating a balanced diet. So I’ve given up almost all of the pills that I used to take daily. The only exceptions are: Vitamin D3 in winter; And Vitamin B12, which plays a vital role in producing red blood cells plus supports nerve cell function and DNA synthesis. I’ve heard older adults often have low levels of B12, so I take a 500mcg tablet each day.
I found useful information on this nutrient in an April 2015 Harvard online article by Linda Antinoro, R.D., L.D.N., J.D., C.D.E. Getting Enough Vitamin B12. Here are excerpts:
Vitamin B12 deficiency occurs when there are low levels of stored B12 in the body. This can lead to:
Anemia- Fatigue
- Weakness
- Soreness of the mouth and tongue
- Constipation
- Decreased appetite
- Weight loss
- Numbness and tingling in the hands and feet
- Dizziness, light-headedness
- Poor memory and confusion
Unfortunately, more people are at risk for deficiency.
-
Aging
As we age, our stomachs produce less gastric acid—a condition called atrophic gastritis. It reduces the body’s ability to absorb vitamin B12 that’s bound to protein in foods. Synthetic B12, which is found in fortified foods and supplements, doesn’t require stomach acid for absorption. To avoid deficiency, the Institute of Medicine and the Dietary Guidelines for Americans recommend that people 50 and older eat B12-fortified foods or take a supplement.
-
Certain medications
Medications for indigestion and reflux work by shutting off gastric acids. These include proton pump inhibitors (PPI), such as esomeprazole (Nexium), omeprazole (Prilosec) and lansoprazole (Prevacid), and histamine-2 receptor agonists (H2RAs), such as famotidine (Pepcid) and ranitidine (Zantac). With less stomach acid, the body can’t absorb as much B12. Metformin, a hypoglycemic agent taken by some diabetics, may also reduce the absorption of B12 by possibly altering intestinal motility.
-
Gastrointestinal disorders or past gastrointestinal surgery
People with certain medical conditions, such as celiac disease and Crohn’s disease, may be unable to absorb adequate B12 from food. Surgery to remove part or all of the stomach can also result in the inability to absorb this vitamin.
-
A vegan diet
Vegans can develop vitamin B12 deficiency because they lack the nutrient in their diets. There are no known plant foods that are natural sources of B12. Fortunately, eating fortified foods, such as breakfast cereals, soy milk and vegetarian meat substitutes, can help prevent a potential deficit. However, research shows that vegans who don’t take a B12 supplement often have inadequate levels.
How Much Dietary B12 Do I Need?
A blood test can determine your B12 levels. Depending on the laboratory, a normal range is anywhere between 200 to 900 picograms per milliliter (pg/ml). Most experts agree that values less than 200 pg/ml make up a B12 deficiency. Others say that a blood level of at least 350 pg/ml is optimal.
The recommended dietary allowance (RDA) for adults is 2.4 micrograms (mcg) a day. Some nutrition experts question if this amount is enough, especially among the elderly. The U.S. Food and Drug Administration sets the Daily Value (DV) for vitamin B-12 at 6 micrograms. People at risk for deficiency probably will benefit from more than 2.4 mcg. There’s no official upper limit for B12 intake so toxicity or overdoing is not a concern.
Best Sources of B12
B12-fortified foods are a good way to get enough of this nutrient, especially if your diet is low on animal foods, such as meats, fish, poultry, milk, cheese and eggs. Some foods are better sources of B12. In a large population-based study, milk and fish were better sources of B12 than meat and eggs. Dairy foods especially are a highly “bioavailable” source of the vitamin. Vitamin B12 in meat may be less bioavailable due to losses during cooking and the presence of collagen, which isn’t digested as well with decreased gastric secretion.
You might want to ask your doctor to check your B12 level. But routinely including B12-containing and fortified foods in your diet—and for us seniors perhaps taking a supplement as well—should do the trick.