Feeling fatigued or forgetful? You may be low in B12

Vitamin B12 deficiency is more common than you may think, but it can be reversed with supplements and the right food choices — learn these four ways to make sure your levels are up
Feeling fatigued or forgetful? You may be low in B12 Getty Images

Fatigue is one of the main complaints that I hear from new patients at my clinic. The reasons behind fatigue can range from insomnia and excessive stress to food allergies or a hormonal imbalance, but more often than not I find that low levels of vitamin B12 — and often iron, as the two go hand in hand — are partially to blame.

What causes vitamin B12 deficiency?

Vitamin B12 is water soluble, which means that the body is unable to store it in large amounts — this makes it especially important to get it in regular doses, either in your diet or through supplements. This can be difficult for some people, particularly vegetarians, vegans, or those with absorption issues related to conditions like celiac disease or Crohn's disease.

The symptoms of a deficiency in vitamin B12 include muscle weakness, low blood pressure, vision problems, memory issues, megaloblastic anemia, fatigue, and mood disturbances.

The good news is that that vitamin B12 is one of the easiest vitamins to supplement, when it's taken in the right form and dosages. Here are four key tips to make sure you hit your B12 requirements and avoid deficiencies.

1. Get your B12 levels checked


Vitamin B12 affects brain function by lowering homocysteine, an amino acid that can have negative health effects when its levels are too high — elevated homocysteine is a risk factor for heart disease, osteoporosis, Alzheimer’s disease, stroke, and increased risk of birth defects.

For this reason, I recommend requesting that your B12 levels are checked when you next see your doctor, especially if you're older than 30. Folic acid/folate and vitamin B6 are also related to keeping your homocysteine levels in check — the optimal value for your fasting homocysteine blood test is less than 6.3. 2. Look inside your medicine cabinet

Prescription and over-the-counter medications can help us treat a particular disease or condition, but they sometimes come with a nutritional cost by increasing our need for certain vitamins and minerals. For example, the birth-control pill causes a decrease in B12, along with zinc, folic acid/folate, B6, and vitamin C, while metformin, which is used to treat diabetes, might reduce the absorption of vitamin B12. These and some other medications can interfere with the absorption of vitamin B12 from food by slowing the release of hydrochloric acid into the stomach. If you have inadequate B12 levels to begin with, or take these medications for a lengthy period of time, you may be more susceptible to a vitamin B12 deficiency.

3. Add B12 to your supplement arsenal

Not all vitamin B12 supplements are created equal. A compromised digestive system can affect your absorption of certain vitamins and minerals, so I prefer to boost a patient’s vitamin B12 levels through lozenges or vitamin B12 injections — both of these methods allow nutrients to bypass digestion and enter directly into the bloodstream.


When selecting a lozenge, look for hydroxocobalamin on the back of the label. When opting for injectible B12, you should request methylcobalamin — it's the form found in food, which makes it easier for your body to absorb. I suggest taking 2,000mcg to 4,000mcg daily, either with or without food. The recommended daily intake of B12 from food is 2.4mcg for adult women, 2.6mcg for pregnant women, and 2.8mcg for lactating women — but absorption of B12 from food is much stronger than from supplements.

I also highly recommend doing the HCL challenge, which is designed to restore the acidity levels of your stomach — low stomach acid can affect your ability to absorb many vitamins and minerals, including B12, from your food.

4. Get more vitamin B12 from your diet In addition to a trip to the health food store, you can boost your vitamin B12 levels by including the following foods in your diet:

  • Liver, beef, braised, one slice: 48.0 micrograms (mcg) per serving
  • Clams, cooked, 3 ounces: 34.2 micrograms (mcg) per serving
  • Trout, rainbow, wild, cooked, 3 ounces: 5.4 micrograms (mcg) per serving
  • Salmon, sockeye, cooked, 3 ounces: 4.8 micrograms (mcg) per serving
  • Trout, rainbow, farmed, cooked, 3 ounces: 3.5 micrograms (mcg) per serving
  • Haddock, cooked, 3 ounces: 1.8 micrograms (mcg) per serving
  • Yogurt, plain, 1 cup: 1.4 micrograms (mcg) per serving
  • Beef, top sirloin, broiled, 3 ounces: 1.4 micrograms (mcg) per serving
  • Tuna, white, 3 ounces: 1.0 micrograms (mcg) per serving
  • Milk, 1 cup: 0.9 micrograms (mcg) per serving
  • Cheese, Swiss, 1 ounce: 0.9 micrograms (mcg) per serving
  • Ham, cured, roasted, 3 ounces: 0.6 micrograms (mcg) per serving
  • Egg, large, one whole: 0.6 micrograms (mcg) per serving
  • Chicken, roasted, half breast: 0.3 micrograms (mcg) per serving

Natasha Turner, N.D. is a naturopathic doctor, Chatelaine magazine columnist, and author of the bestselling books The Hormone Diet and her newest release, The Supercharged Hormone Diet, now available across Canada. She is also the founder of the Toronto-based Clear Medicine Wellness Boutique.



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