Vitamin B12 is a vital nutrient that your body requires for many essential functions, such as making red blood cells, DNA, and energy, as well as supporting your brain and nervous system health. However, your body cannot produce vitamin B12 on its own, so you need to obtain it from your food or from supplements.
Why is vitamin B12 important?
Vitamin B12 helps your body in several ways, such as:
Producing healthy red blood cells. Vitamin B12 works with another vitamin called folate to make red blood cells that carry oxygen throughout your body. If you lack vitamin B12, you may develop a type of anemia called megaloblastic anemia, which can cause symptoms like tiredness, weakness, and shortness of breath.
Supporting your brain and nervous system. Vitamin B12 is involved in the creation of neurotransmitters, which are chemical messengers that help your brain cells communicate with each other. Vitamin B12 also helps maintain the protective coating around your nerve fibers, called the myelin sheath. Low levels of vitamin B12 can affect your memory, mood, and cognitive function.
Making DNA and energy. Vitamin B12 is needed for the replication and repair of your genetic material, or DNA. It also helps convert the food you eat into energy that fuels your cells and organs.
Protecting your heart health. Vitamin B12 may lower your risk of heart disease by lowering the levels of a harmful amino acid called homocysteine in your blood. High homocysteine levels can damage your blood vessels and increase your risk of blood clots, stroke, and heart attack.
How much vitamin B12 do you need?
The amount of vitamin B12 you need depends on your age, gender, and health status. The recommended dietary allowance (RDA) for vitamin B12 for adults is 2.4 micrograms (mcg) per day. However, some people may need more or less depending on their medical conditions or medications.
For example, pregnant and breastfeeding women need more vitamin B12 to support the growth and development of their babies. The RDA for pregnant women is 2.6 mcg per day and for breastfeeding women is 2.8 mcg per day.
On the other hand, some people may have trouble absorbing vitamin B12 from food or supplements due to certain factors, such as:
Age. As you get older, your stomach produces less acid, which is needed to release vitamin B12 from food. This can reduce the amount of vitamin B12 you absorb by up to 50%. People over 50 years old are advised to get most of their vitamin B12 from fortified foods or supplements.
Diet. If you follow a vegan or vegetarian diet, you may not get enough vitamin B12 from plant-based foods alone. Animal products are the only natural sources of vitamin B12, so you may need to eat fortified foods or take supplements to meet your needs.
Medical conditions. Some diseases or surgeries can affect your ability to absorb vitamin B12 from food or supplements. These include pernicious anemia, Crohn’s disease, celiac disease, gastric bypass surgery, and infections in your stomach or intestines.
Medications. Some drugs can interfere with the absorption or metabolism of vitamin B12 in your body. These include metformin (for diabetes), proton pump inhibitors (for acid reflux), antibiotics (for infections), and anticonvulsants (for seizures).
If you belong to any of these groups, you may need to take higher doses of vitamin B12 supplements or get injections from your doctor to prevent or treat a deficiency.
What are the signs and symptoms of vitamin B12 deficiency?
Vitamin B12 deficiency can cause a range of symptoms that may vary depending on the severity and duration of the condition. Some common signs and symptoms include:
Anemia. This is the most obvious sign of vitamin B12 deficiency. It can cause pale skin, fatigue, weakness, dizziness, shortness of breath, chest pain, and rapid heartbeat.
Neurological problems. Vitamin B12 deficiency can damage your nerves and affect your brain function. It can cause tingling or numbness in your hands and feet, balance problems, difficulty walking, confusion, memory loss, depression, and dementia.
Glossitis. This is a condition where your tongue becomes inflamed, swollen, red, and painful. It can also affect your taste buds and make it hard to eat or speak.
Skin problems. Vitamin B12 deficiency can cause changes in your skin color, such as patches of hyperpigmentation (darkening) or hypopigmentation (lightening). It can also cause vitiligo, which is a loss of skin pigment that results in white spots.
Hair and nail problems. Vitamin B12 deficiency can affect the growth and quality of your hair and nails. It can cause hair loss, brittle nails, and ridges or grooves on your nails.
If you have any of these symptoms, you should see your doctor and get tested for vitamin B12 deficiency. A simple blood test can measure the level of vitamin B12 in your body and help diagnose the condition.
What foods are high in vitamin B12?
The best way to get enough vitamin B12 is to eat a balanced diet that includes foods that are rich in this nutrient. Some of the foods that are high in vitamin B12 are:
Animal liver and kidneys. These organ meats are some of the most concentrated sources of vitamin B12. A 3.5-ounce (100-gram) serving of lamb liver provides an incredible amount of vitamin B12, more than 3,000 times the daily value. Lamb, beef, and veal kidneys are also very high in vitamin B12, providing about 3,000 times the daily value per 3.5-ounce (100-gram) serving.
Clams. These shellfish are also packed with vitamin B12. You can get more than 7,000 times the daily value in just 20 small clams (190 grams). Clams are also a good source of iron, protein, and antioxidants.
Sardines. These small fish are another excellent source of vitamin B12. A 1-cup (150-gram) serving of drained sardines provides more than 500 times the daily value for vitamin B12. Sardines are also rich in omega-3 fatty acids, which can benefit your heart health.
Beef. This red meat is a good source of vitamin B12, especially if you choose lean cuts. A 3.5-ounce (100-gram) serving of cooked beef provides about 85% of the daily value for vitamin B12. Beef is also high in protein, iron, zinc, and selenium.
Fortified cereal. This is a great option for vegetarians, vegans, or people who don’t eat much animal products. Fortified cereals are grains that have been enriched with vitamins and minerals, including vitamin B12. A 1-cup (29-gram) serving of some fortified cereals can provide up to 100% of the daily value for vitamin B12. However, you should check the nutrition label to make sure the cereal you choose has added vitamin B12 and not just other nutrients.
Tuna. This popular fish is another good source of vitamin B12. A 3-ounce (85-gram) serving of canned tuna in water provides about 70% of the daily value for vitamin B12. Tuna is also high in protein, selenium, and omega-3 fatty acids.
Trout. This freshwater fish is similar to salmon in terms of its nutritional profile. A 3-ounce (85-gram) serving of cooked trout provides about 70% of the daily value for vitamin B12. Trout is also rich in protein, omega-3 fatty acids, selenium, and phosphorus.
Salmon. This fatty fish is one of the most nutritious foods you can eat. A 3-ounce (85-gram) serving of cooked salmon provides more than 50% of the daily value for vitamin B12. Salmon is also loaded with protein, omega-3 fatty acids, selenium, potassium, and vitamin D.
Milk. This dairy product is a good source of vitamin B12, especially if you choose low-fat or skim varieties. A 1-cup (240-milliliter) serving of milk provides about 45% of the daily value for vitamin B12. Milk is also high in calcium, protein, phosphorus, and riboflavin.
Yogurt. This fermented dairy product is another good source of vitamin B12, especially if you choose plain or low-fat varieties. A 6-ounce (170-gram) serving of yogurt provides about 25% of the daily value for vitamin B12. Yogurt is also high in calcium, protein, probiotics, and iodine.
Eggs. These versatile foods are a good source of vitamin B12, especially if you eat the whole egg and not just the white. One large egg provides about 10% of the daily value for vitamin B12. Eggs are also high in protein, choline, and lutein.
These are some of the foods that are high in vitamin B12. However, you should also be aware of the factors that can affect your vitamin B12 absorption and status, such as age, diet, medical conditions, and medications. If you have any concerns or questions about your vitamin B12 intake or level, you should consult your doctor. They can help you determine the best way to meet your vitamin B12 needs and prevent or treat a deficiency.
Dr. Karuturi Subrahmanyam, MD, FRCP (London), FACP (USA)
Internal Medicine Specialist
Phone : 85000 23456