B12 is one of the most recognizable vitamins that make up the B-complex group of vitamins, largely because it has been touted by supplement and energy-drink/food manufacturers as having performance-enhancing effects without the negative aspects of more common ingredients like caffeine and sugar. While some have found this use of the vitamin helpful, it really does do so much more than that.
What Is It?
Vitamin B12 is a water-soluble vitamin that is part of the group of vitamins comprising the B-vitamin complex.
What Is Its Biological Role?
Vitamin B12 is responsible for helping in the creation of DNA, a basic requirement for the formation of all cells. Vitamin B12 consumed from foods is bound to the protein in those foods, and so before it can be used by the body it must be made available by detaching it from those proteins.
This process happens naturally during digestion. Along with folate, vitamin B12 also has a significant role in lowering levels of homocysteine in the blood. Interestingly, recent studies have suggested that B12 may be used therapeutically to treat conditions like Alzheimer’s and dementia; dementia patients seem to have very high levels of homocysteine in the blood compared to unaffected members of their demographic.
The hope is that therapeutically high doses of B12 may help treat these conditions because B12 has such a strong ability to lower the body’s homocysteine levels.
How Does It Help Bodybuilders and People Who Work Out?
Homocysteine is a free radical in the blood  that can have negative effects on your cardiovascular health. This particular free radical occurs in greater numbers when individuals undergo intense workouts.
The more intense the workout, the higher the amount of homocysteine the body produces. This can make it more difficult to recover after a workout as well. Vitamin B12 can significantly lower an individual's levels of homocysteine, decreasing both recovery time and risk of cardiovascular problems as a result of high homocysteine levels.
Also, vitamin B12 is frequently added to energy drinks and other performance enhancing products because of the propensity of B-complex vitamins to increase energy levels. While there is no officially recognized medical evidence that this is effective, many users of these types of products have found a performance enhancing effect can be achieved without the use of caffeine or sugar.
What Foods Contain It?
Vitamin B12 can be easily found in the diet of all omnivores, as it is bound to proteins in the food you eat. This includes meats, fish, eggs, milk, and other dairy products. Two of the best sources of B12 are beef liver and clams.
Beef liver, however, has very high levels of cholesterol and should be consumed in moderation for this reason. Most cold breakfast cereals are high in vitamin B12 and can be an easy way for vegetarians to get bioavailable B12 from their diet.
Ovo-vegetarians can also make a point of consuming eggs regularly to bolster their vitamin B12 consumption from dietary sources.
How Much Of It Do You Need?
Recommended daily intake levels for vitamin B12 vary throughout childhood, but normalize at 14 years of age. The recommended daily intake for anyone aged 14 and over is 2.4mcg per day.
This dosage can change if you are pregnant or breastfeeding. For pregnancy, recommended daily intake increases to 2.6mcg per day, and increases to 2.8mcg per day if you are breastfeeding.
Are There Risks Associated With Consuming Too Much Of It?
According to the National Institute of Health, there is no officially established upper limit for safe consumption of vitamin B12, and no side effects of excessive consumption that could be characterized as B12 toxicity. Presumably, this has to do with the way B12 is processed by the body, and the body’s ability to rid itself of excess B12 via urine and sweat.
Are There Risks Associated With Consuming Too Little Of It?
Not consuming enough vitamin B12 can have negative consequences. B12 deficiency can cause permanent damage to your nervous system, numbness or tingling in the extremities, tiredness, weakness, dizziness, and other similar symptoms.
Eventually, B12 deficiency can lead to a condition known as megaloblastic anemia where your red blood cells do not form properly and so cannot effectively carry oxygen to other tissues inside your body. Groups at particular risk for B12 deficiency are adults over age 50, who may have lower levels of the stomach acids required to make B12 bioavailable, and individuals with a condition called pernicious anemia.
Pernicious anemia involves the body’s inability to produce intrinsic factor, something normally present in the stomach that helps absorb certain vitamins like B12.
While ensuring that you get all of your needed nutrients, including vitamins and minerals, is important for everyone, vitamin B12 does seem to have particularly useful properties for fitness enthusiasts.
It just fits perfectly into a gym rat’s routine, helping preventing one of the few negative consequences of exercise and helping to improve energy. Anyone interested in working out or staying healthy and energetic may want to give the vitamin superhero some consideration.
 University of Maryland Medical Center. Vitamin B12 (Cobalamin). University of Maryland Medical Center, 2015.
 WebMD. Vitamin B12: Uses, Side Effects, Interactions, and Warnings. WebMD, 2016.
 WebMD. Homocysteine Levels and Heart Disease Risk. WebMD, 2016.