Vitamin B12

Top Benefits

Vitamin B12 is an important nutrient to the body responsible for keeping our nerve cells, red blood cells and DNA in check. It’s found in a variety of animal foods and fortified foods like cereals or nutritional yeast. How vitamin B12 can help our bodies, as well as what happens when we are deficient in it, has been much studied. Here are the top researched health benefits of vitamin B12: 

  1. Helps form red blood cells and make DNA
  2. Supports bone health 
  3. Helps to prevent anemia 
  4. Improves memory
  5. May help prevent birth defects 
  6. Supports eye health 
  7. Plays a role in mood and depression


Vitamin B12 is a nutrient that is not only the largest but also the most structurally complicated vitamin. It serves many different important functions in the body, including keeping nerve cells healthy, helping red blood cells form, and making DNA. It is an essential vitamin that our body greatly needs but cannot produce on its own. 

Also known as cobalamin, vitamin B12 is a waste soluble vitamin, like all other B vitamins. That simply means it can dissolve in water and travel through the bloodstream. Interestingly enough, our bodies can store vitamin B12 for up to four years. Any excess amount is simply excreted through urine. 

Vitamin B12 is found naturally in a wide variety of animal foods, and it is sometimes added to fortified foods like cereals or nutritional yeast. Plant foods have no vitamin B12 unless they’re fortified. B12 is found in almost all multi-vitamins and can be taken as an oral supplement or an injection.

Most people get enough B12 from the food they eat, while other people have trouble absorbing it no matter how much they ingest. Older adults, people suffering from pernicious anemia, and those with digestive disorders like Crohn’s disease or Celiac disease may all have trouble getting enough vitamin B12. The same can often be true of people who eat little or no animal foods like vegans or vegetarians. Fortunately, fortified foods, dietary supplements and B12 shots can help if levels become too low. 

But how do you know if your B12 level is too low? Deficiency causes symptoms like weakness, tiredness, constipation, loss of appetite, weight loss and megaloblastic anemia. Tingling of the hands and feet or poor balance may also occur. Consult your doctor if you are having these symptoms and suspect a B12 deficiency. A simple blood test can help determine if there is enough present or not. 

Vitamin B12 can benefit our bodies in a variety of different ways. It supports the health of our bones, our eyes, our memories, our mood and even our energy levels. Babies require an adequate amount of vitamin B12 from their mothers in order to develop properly. B12 can also help to keep our bodies from becoming anemic. 

Nutritional Information 

There are a variety of sources of vitamin B12 both in food and supplement form. The best sources are beef, liver and clams. Other sources include fish, meat, poultry, eggs, milk and other dairy products. Some foods like cereal and nutritional yeasts are fortified with B12. 

This chart contains the best places to find vitamin B12, listing their servings in micrograms and the corresponding daily value percentage. 


mcg %DV

Clams, cooked, 3 ounces 84.1 1,402

Liver, beef, cooked, 3 ounces 70.7 1,178

Nutritional yeasts, fortified with 100% of the DV for vitamin B12, 1 serving

6.0 100

Trout, rainbow, wild, cooked, 3 ounces 5.4 90

Salmon, sockeye, cooked, 3 ounces 4.8 80

Trout, rainbow, farmed, cooked, 3 ounces 3.5 58

Tuna fish, light, canned in water, 3 ounces 2.5 42

Cheeseburger, double patty and bun, 1 sandwich 2.1 35

Haddock, cooked, 3 ounces 1.8 30

Breakfast cereals, fortified with 25% of the DV for vitamin B12, 1 serving

1.5 25

Beef, top sirloin, broiled, 3 ounces 1.4 23

Milk, low-fat, 1 cup 1.2 18

Yogurt, fruit, low-fat, 8 ounces 1.1 18

Cheese, Swiss, 1 ounce 0.9 15

Beef taco, 1 soft taco 0.9 15

Ham, cured, roasted, 3 ounces 0.6 10

Egg, whole, hard boiled, 1 large 0.6 10

Chicken, breast meat, roasted, 3 ounces 0.3 5


Bone Health 

Having the proper amount of vitamin B12 in your diet may be beneficial to bone health. It has a positive effect on bone building cells. When bones don’t receive the proper nutrients and have decreased mineral density, they can become weakened and fragile over time. 

One study that looked at 2,500 people who had a vitamin B12 deficiency. Tests showed that they had lower than normal bone mineral density. A different study done at Tufts University reported that low levels of vitamin B12 were linked to a higher risk of osteoporosis in both men and women. Additional studies have also linked low B12 levels with poor bone health and osteoporosis. 

Since vitamin B12 is found mainly in meat and fish, vegans may be at risk for bone loss. Fortunately, B12 supplements, injections or vegan-friendly fortified foods may help. 


Vitamin B12 may play a role in preventing brain atrophy — a loss of neurons often associated with dementia, or memory loss. Vitamin B12 is necessary for healthy brain function as well as maintaining the protective covering around our nerves. In older adults, deficiency in vitamin B12 has been associated with memory loss. 

A study conducted on people with early-stage dementia showed that by combining B12 with omega-3 fatty acid supplements, researchers were able to slow mental decline. A different study reported that when B12 levels are on the low side, it contributed to poor memory performance. 

More research is needed to determine the full effect vitamin B12 may have on memory and cognitive function. 


One of the common signs of vitamin B12 deficiency is lack of energy. If you have a significant deficiency, taking vitamin B12 either as food or a supplement can likely improve your energy level. 

Although B12 is sometimes praised for providing a surge of energy, at the current time, there is no scientific evidence to suggest that it can boost energy levels if you already have a sufficient amount in your system. That’s because B12 doesn’t necessarily provide energy, but it does play a role in your body’s energy production. 

The bottom line is, have the right amount in your body so you can ward off fatigue, but don’t think it’s a cure all if you already have enough B12.

Hair Skin and Nails 

Because of the role vitamin B12 plays in cell production, maintaining proper levels can help to support healthy hair, skin and nails. 

Low levels of vitamin B12 can cause several different dermatological conditions, including nail discoloration, vitiligo, hyper pigmentation, as well as angular stomatitis, or cracked mouth corners. 

By supplementing with B12, people with deficiencies can improve dermatologic symptoms. However, it is important to note that if you are not deficient in B12, taking a supplement is unlikely to improve skin, strengthen nails or make hair healthier. 


Macular Degeneration 

Macular degeneration is a degenerative condition that affects the central part of the retina. It results in distortion or loss of central vision. 

Research is showing that adequate levels of vitamin B12 may help to prevent the risk of age-related macular degeneration. That’s because B12 lowers the amino acid homocysteine in your blood. 

A study that looked at 5,000 women who were 40 or older showed that by supplementing with vitamins B12 and B6 along with folic acid, the risk of macular degeneration was reduced. In this 7 year study, the likelihood of any form of the condition developing was 34% lower, and an impressive 41% lower for more severe types. 

More studies are needed to fully understand how vitamin B12 can promote vision health and help battle macular degeneration. 


One of Vitamin B12’s most important roles is helping to form and develop red blood cells. Healthy red blood cells are small and round in shape. 

However, if you are deficient in B12, the red blood cells become large and oval instead. When that happens, they are unable to move from the bone marrow into the blood stream at the proper rate. This causes mesoblastic anemia. 

When you’re anemic, you don’t have enough red blood cells to do the important job of transporting oxygen to your vital organs. That’s why many people with anemia feel week and fatigued. 

Having the proper level of B12 in your body, easily measured by a blood test, could be important in helping to prevent anemia. 

Depression and Mood 

Vitamin B12 plays a vital role in synthesizing and metabolizing serotonin, a chemical that is responsible for helping regulate mood. A deficiency in B12 may lead to decreased serotonin production, which may cause the feelings of depression. Research supports using B12 supplements for people who are deficient and battling depression. 

One study of depressed patients who were low in B12 levels found that when they received both antidepressants and vitamin B12, they were more likely to show improvement than those treated with antidepressants only. 

In the Journal of Psychopharmacology, researchers conducted a study in 2005 that reviewed depression and low B12. They found significant evidence that a decrease in B12 serum correlates with an increase in depression. Their research further stated that high B12 status may be connected to better treatment of depression. 

It should be noted that research has found that vitamin B12 supplements may improve mood and depression in people with a deficiency. However, current studies do not suggest that it has the same effect on patients with normal B12 levels. 

Birth Defects 

For a fetus’s brain and nervous system to develop properly, sufficient levels of B12 are needed from the mother. In fact, they are crucial. In the beginning stages of pregnancy, vitamin B12 deficiency may increase the risk of birth defects. It may also contribute to premature births and miscarriages. 

One study showed that women with low B12 levels (lower than 250 mg/dL) were 3 times more likely to give birth to a child with defects, as opposed to those mothers who had adequate B12. In women who had levels below 150 mg/dL, they had 5 times the chance of having a child with birth defects as opposed to women with levels above 400 mg/dL. 

If you are pregnant or trying to become pregnant, check with your health care provider to make sure your vitamin B12 levels are at the appropriate level. It’s not only important to your health, but also to the health of your child. 


Side Effects 

When taken at appropriate doses, vitamin B12 supplements are generally considered safe. To date, the side effects are very limited. It is not even considered to be toxic in high quantities, like 1000 mcg. There was one reported case in Germany in 2001 of someone having rosacea as a result of B-12. Cases of acne triggered by B12 have also been documented.

However, a B12 deficiency may occur when the body either doesn’t get enough B12, or can not absorb what it needs. Deficiencies can occur in the following: those over age 50, vegans and vegetarians, those who have had stomach or intestinal surgery (like weight loss surgery), or people with Celiac Disease or Crohn’s Disease. 

If you have a low level of B12, you may experience the following symptoms: anemia, loss of balance, weakness or fatigue, numbness or tingling in the arms and legs.


Vitamin B12 can interact or interfere with certain medications. In fact, in some circumstances, medicines can lower B12 levels in the body. Here are examples of medicines than can interfere with your body’s ability to absorb B12: 

  1. Chloramphenicol (Chloromycetin®), an antibiotic that is used to treat certain infections.
  2. Proton pump inhibitors, such as omeprazole (Prilosec®) and lansoprazole (Prevacid®), that are used to treat acid reflux and peptic ulcer disease.
  3. Histamine H2 receptor antagonists, such as cimetidine (Tagamet®), famotidine (Pepcid®), and ranitidine (Zantac®), that are used to treat peptic ulcer disease.
  4. Metformin, (Glumetza, Glucophage, Fortamet) a drug used to treat diabetes.
  5. Colchicine (Colcrys, Mitigare) an anti-inflammatory drug used to prevent and treat gout attacks. 
  6. Vitamin C (ascorbic acid) supplements might reduce the available amount of vitamin B-12 in your body.
  7. Aminosalicylic acid, a drug used to treat digestive problems.  

Tell your healthcare providers about any dietary supplements and medicines you take. They might be able to recommend changing drugs, or timing doses differently to help offset interactions. 


The amount of vitamin B12 that is needed each day depends on a person’s age. Here is the average daily recommend dose in micrograms, or mcg. 

Life Stage Recommended Amount

Birth to 6 months 0.4 mcg

Infants 7-12 months 0.5 mcg

Children 1-3 years 0.9 mcg

Children 4-8 years 1.2 mcg

Children 9-13 years 1.8 mcg

Teens 14-18 years 2.4 mcg

Adults 2.4 mcg

Pregnant teens and women 2.6 mcg

Breastfeeding teens and women 2.8 mcg


General Information and Overview

Nutritional Information

Bone Health



Hair, Skin and Nails

Depression and Mood

Red Blood Cell Formation


Macular Degeneration

Side Effects, Interactions and Dosing