Vitamin B12 is essential for DNA synthesis, brain function, nervous system function and red blood cell formation. It’s also essential for heart health as it aids in the breakdown of homocysteine which is associated with an increased risk of heart disease. Although required for proper metabolic function, the human body does not create this vitamin and must obtain it from dietary sources. The most common food sources include fish, liver, beef, eggs, cheese and poultry. This is because the only organisms to produce vitamin B12 are certain bacteria. Some of these bacteria are found in the soil , so when animals eat grass they take in B12. It is the most chemically complex of all the vitamins, having cobalt at the centre of the molecule (vitamin B12 is sometimes called cobalamin). See also the also the full B family of vitamins.
The total amount of vitamin B12 stored in body is about 2–5 milligram in adults. Around 50% of this is stored in the liver. There are 3 natural forms of vitamin B12 and one synthetic:
- Methylcobalamin. This is the most active form in the human body.
- Cyanocobalamin. (synthetic version of vitamin B-12 found in cheap supplements).
How much vitamin B12 do I need?
The RDA for adult vitmin B12 is 2.4mcg per day. You will also need more if you drink alcohol frequently. Absorption is also an issue in older men and women. Vegans are also at particular risk.
According to the USDA), nearly 40% of the U.S. population have marginal vitamin B12 status and 9% are deficient. A good whole food diet will easily give a good amount of vitamin B12, particularly if you consume liver, clams, oysters, mussels or fish. B12 is tightly bound to proteins and high acidity is required. Animal meat from industrial farms are low in B12 because they are not eating grass and good bacteria.
Dr Mercola cites: "If you're frequently beset by fatigue and general lack of energy, you may be experiencing the onset of B12 deficiency. Other seemingly unrelated symptoms such as poor memory, shortness of breath, loss of taste and smell, depression and tingling in your extremities, can be indicative of low B12".
Vitamin B12 Foods
Clams (100g): 49mcg. A study found that canned clams used in a soup provided 6-40mcg per bowl. Try and eat clam chowder. Clams are also really high in iron.
Beef liver (30g): 25mcg. Not everyone is a liver fan, but pâté is a great tasting alternative. You can make your own very easily. Try and avoid supermarket bought pate.
Oysters (100g): 16mcg
Mussels (100g): 12mcg
Crab (100g): 9mcg
Sardines (100g): 8mcg
Sockeye salmon (100g): 5mcg
Mackerel: (100g): 9mcg
Tuna fish (1 can): 2.5mcg
Haddock (100g): 2.5mcg
Lamb: (100g): 3mcg
Nutritional yeast (1 tbsp fortified): 2.4mcg
Beef (100g): 2.6mcg
Swiss cheese (100g): 3mcg
Eggs (1 medium): 0.5mcg
Vitamin B12 testing
We would recommend a vitamin B12 test (particularly for over 50 year olds) because the consequences of a deficiency are very serious. There are several ways to test your vitamin B12 levels. You can get a blood or take a urine test. These tests will look at the levels of your:
- Overall vitamin B12
- Methylmalonic acid (MMA)
- Holotranscobalamin (holoTC)
MMA and holoTC may be more accurate at reading low B12 levels because they represent active B12 vitamin. If you have low B12 you should have a large oral dose of methylcobolamin. You may also have additional blood tests to check for a condition called pernicious anaemia. You should certainly get tested if you have had exposure to laughing gas.
Visiting your dentist can wipe out your B12!
Nitrous oxide (laughing gas) is a gas that's used in hospitals and dentists. It's also the gas used in many pressurised canisters such as whipped cream and spray oil. Nightclubs have also been known to sell balloon full of laughing gas. Nitrous oxide can cause severe nitrous oxide induced B12 deficiency due to its conversion of the active monovalent form of vitamin B12 to its inactive bivalent form. So if you have laughing gas, eat plenty of liver and clams!
Medicines can affect B12 levels and cause dangerous deficiencies.
- Antibiotics (hugely affect the gut flora).
- Metformin for low blood sugar.
- Stomach acid-altering medications.
- Proton-pump inhibitor (PPIs) like Prevacid or Nexium or H2 blocker such as Pepcid or Zantac.
- Certain genetic conditions can hinder the body’s use of vitamin b12.
Take the correct B12 supplement
You should take Methylcobalamin. Typically when you go to your doctor and get a Vitamin B12 injection, or take a B12 supplement, you will get Cyanocobalamin. If you go to a knowledgeable Doctor, you will likely get the more expensive methylcobalamin. Cyanocobalamin contains a cyanide molecule. Although it's too small to be harmful, your body will still need to remove and eliminate this compound. As it has no use for the cyano-compound itself, it will set about converting any cyanocobalamin you take into methylcobalamin as soon as possible – it’s the methyl compound that the human body needs to function properly.
A multivitamin will typically contain vitamin B12. Centrum for men contains 21.6mcg of cyanocobalamin. So if you have a pretty awful diet and you rely on a multi-vitamin, you may be B12 deficient due to absorption issues.
Vitamin B12 for children
It is not uncommon for children to have pretty terrible diets, often the opposite of their parents. Many children and adolescents switch to become vegetarians or vegans. Whilst many vegetarians take dietary intake seriously, many take the "skittles and french fries approach". So getting enough B12 into their diet is critical for healthy growth.
Sources: ncbi.nlm.nih.gov, mercola.com, clinicaltrials.gov, draxe.com, drrostenberg.files.wordpress.com