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Vitamin B-12 Deficiency

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May 25, 2015 (Updated: August 16, 2018)
Lily Moran

When new patients come to my practice, I run a battery of tests to get an overall “baseline” look at their health. Along with the standard workup that includes complete blood count, metabolic panel, and lipoprotein profile, I always check vitamin B status.

Many of my patients scoff about this. They tell me, “You don’t need to test my B levels. I feel great! I’m not tired at all!” But a few days later, about half of these people are shocked to learn they have low levels of one key B vitamin—B12.

Why do B vitamins matter so much? Well, you probably know that they’re closely linked to energy and vitality. But that’s really just the tip of the iceberg. This family of nutrients performs countless unique and important functions throughout the body.

Here’s a rundown of the entire complex of B vitamins and just a few of their jobs, apart from cellular energy production:

  • Thiamin (B1) is required for the synthesis of DNA and RNA.
  • Riboflavin (B2) acts as an antioxidant by fighting harmful free radical damage throughout the body.
  • Niacin (B3) is involved in hundreds of chemical reactions and the production of sex and stress-related hormones. It also helps to maintain heart health, lower cholesterol, improve memory, and even alleviate arthritis.
  • Pantothenic acid (B5), like B3, plays a role in hundreds of cellular reactions. It synthesizes essential fats, steroid hormones, cholesterol, melatonin and various neurotransmitters.
  • Pyridoxine (B6) aids in the normal function of red blood cells, certain hormones, as well as the nervous system. It also metabolizes glucose and various amino acids.
  • Biotin (B7) is integral for the health of your hair, skin, and nails.
  • Folic acid (B9) synthesizes DNA and aids in the creation of red blood cells. It’s most commonly known for preventing birth defects (of the spinal cord and nervous system) in developing fetuses.
  • Cobalamin (B12) plays largest role in cellular energy. It’s also necessary for proper functioning of the nervous system and for red blood cell formation.

While you can have low blood levels of any of these nutrients, true deficiencies are pretty rare (at least in developed countries) because the B vitamins are so abundant in our food supply. However, even with good nutrition, the most common deficiency, by far, is B12.

Here’s how you can make sure you’re getting enough of this critical nutrient.

Bone Up on B12

By some estimates, up to 40 percent of the population does not have sufficient levels of B12.

This vitamin is found primarily in animal-sourced foods—all meats, dairy products, eggs, and shellfish. Liver, sardines, and salmon contain the greatest amount.

Knowing this, you would think that vegetarians and vegans are the only people at risk for B12 deficits. But even many meat eaters can lack B12, mainly due to poor absorption of the vitamin.

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In younger people, use of acid-blocking medications, and disorders such as Crohn’s disease, leaky gut, diarrhea, and other gastrointestinal problems, affect the body’s ability to absorb and use the vitamin. And in older people, a condition called hypocholorhydria—when the stomach does not produce enough acid to facilitate nutrient uptake—can be blamed.

B12 deficiency can cause a wide variety of debilitating symptoms ranging from exhaustion and lethargy to depression, anxiety, memory loss, confusion, and other Alzheimer’s-like symptoms.

B12 affects neurological function so much because it is heavily involved in the production of myelin sheath—the layer of protective insulation surrounding the nerves in your brain and throughout your body. Without the proper insulation, nerve impulses and message transmissions can “misfire” and run amok.

The Dietary Reference Intake (DRI) for B12 is between 2-3 mcg daily. The Center for Food Safety and Applied Nutrition actually recommends 6 mcg daily, based on a 2,000-calorie diet.

In my opinion, it’s better to err on the side of the higher dose—especially since absorption problems are so common with age. Plus, it’s nearly impossible to overdose, since B12 has very low toxicity.

If you have severe B12 deficiency, I recommend injections of the vitamin, which the body absorbs very rapidly. Most doctors across the country can now administer these quick and easy shots right in their office.

For everyone else—especially vegetarians, vegans, and those age 50 and older—I suggest taking an oral B12 supplement every day. The methylated form of B12 (methylcobalamin) is best. Unfortunately, it’s not always easy to find in your average grocery store. Your best bet is to visit your local health food store or shop a reputable online supplement retailer.

If you’re experiencing any of the symptoms I mentioned earlier, start taking B12 today. Your body—and especially your mind—will thank you.

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