Vitamin B12 has always been an important and essential nutrient, but as more and more people turn to vegetarian and vegan diets or simply reduce their meat consumption, focus on this vitamin has increased. Most natural sources of vitamin B12 are animal products.
Vitamin B12 is a complex, water-soluble vitamin required for proper red blood cell formation, cell metabolism, neurological function, and DNA synthesis. The U.S. nutritional recommendation for B12 is 2.4 mcg per day for adults. While B12 can remain stored in the liver for several years, markers of B12 deficiency usually begin to appear within a few months of insufficient supply.
The best way to get B12 is through natural food sources. The vitamin is most abundant in beef and chicken (which have the most), fish, other poultry, eggs, milk, and milk products. Honey is the only animal product that does not contain B12. Since plant foods lack this vital nutrient, vegans should consume B12-fortified foods, nutritional yeast, and supplements. Although seaweeds and blue algae contain B12, most experts agree the body cannot properly absorb and utilize the nutrient in this form.
Vitamin B12, bound to protein in food, is released by the activity of hydrochloric acid and gastric protease in the stomach. A healthy body can absorb about 50 to 60% of the vitamin B12 it consumes, because the capacity of intrinsic factor, a gastric glycoprotein that aids in B12 absorption, is limited. When oral doses of B12 exceed one or two mcg at a time, the body's ability to absorb the nutrient decreases. Therefore, experts recommend obtaining multiple small doses through food, or a larger supplemental dose, to maintain optimal B12 levels.
Since we need B12 for many functions in the body, a deficiency is not something to take lightly. The National Institute of Health (NIH) estimates that 1.5% to 15% of Americans are deficient in vitamin B12. Early symptoms of B12 deficiency are numbness and a pins and needles sensation known as paresthesia. People may also experience problems with balance, tiredness, joint pain, weakness, constipation, mood swings, lack of appetite, unexplained weight loss, poor memory, and megaloblastic anemia. Additionally, approximately 50% of patients with a deficiency begin to exhibit the symptoms while their lab values still show normal B12 levels -- various interactions can mask deficiencies.
The percentage of people with B12 deficiencies may seem strangely uncertain. This is because other nutrients, such as folic acid, can mask vitamin B12 deficiencies until they advance. Large quantities of folic acid can help correct megaloblastic anemia, a condition caused by B12 deficiency. However, even folate cannot reduce the cognitive decline and neurological damage that a lack of B12 will eventually cause. Some studies suggest folate may even worsen the symptoms. Healthy adults should not have more than 1,000 mcg of folic acid per day.
The National Institutes of Health recommends pregnant women consume 2.6 mcg of B12 daily and nursing mothers 2.8 mcg of B12 per day. Folic acid has many benefits for developing babies, and so does vitamin B12. Good levels of folate can help prevent spina bifida, neural tube, and other neurological defects. Increasing vitamin B12 with supplements and diet changes that incorporate fortified foods and those that naturally contain B12 can ensure enough of the vitamin is being absorbed to provide for the growing fetus. During pregnancy, vitamin B12 crosses the placenta to support nervous system development. After birth, babies get vitamin B12 from breast milk or formula.
Despite consuming animal products, the elderly population is at high risk for developing B12 deficiencies. As we age, our bodies absorb less B12 because the amount of hydrochloric acid in the stomachs decreases. The Institute of Medicine recommends adults over the age of 50 get most of their vitamin B12 from fortified foods or vitamin supplements due to absorption issues.
While most vegans eat enough B12 to avoid neurological damage and anemia, many do not get enough to reduce the risk of heart disease or pregnancy complications. B12-fortified breakfast cereals, almond milk, and soy milk are quite common. By fortifying foods with vitamins or minerals often deficient in specific populations, individuals have greater access to these nutrients.
B12 plays a role in nerve growth and brain cells, so it makes sense that it is linked to mood regulation. The vitamin helps produces brain chemicals responsible for improved mood, which may help treat depression, stress, and anxiety disorders. One of the symptoms of B12 deficiency is mood swings, and research shows many people with clinical depression are deficient in the vitamin. Supplementation can help balance hormones and restabilize neuron function. A nourished brain is more likely to feel positive emotions than a malnourished one.
B12 is a key player in cell reproduction, which is essential for healthy skin, nails, and hair. The vitamin also plays an important role in the formation of red blood cells. Healthy blood cells lead to improved circulation to the scalp and support healthy hair follicles. Vitamin B12 deficiency has been linked with changes in skin pigment and cracking and inflammation at the corners of the mouth.
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