Thinking of going vegan? Read this first.

What you need to know about vitamin B12, before deciding.

Vitamin B12 is the largest and most complex of all vitamins, found only in animal-based foods. Plants do not make, use, or contain this vitamin. Even so, many people make the conscious decision to avoid all foods containing natural B12. It is vital that they supplement their diets, and monitor their B12 status, because deficiency can have devastating consequences.

A water-soluble vitamin, B12 is crucial to the brain and nervous system, red blood cell formation and DNA.

This vitamin is made exclusively in the guts of animals by bacteria. It then migrates from the gut to muscle. The higher predatory animals are the best sources, along with seafood and fish.

Absorption — bioavailability — of B12 can vary, depending on the source. About 50% of B12 from meat and fish is absorbed into the bloodstream. However, only around 9% of B12 in eggs is bioavailable. Milk contains surprisingly little B12.

Early, mild symptoms of vitamin B12 deficiency include:

• Fatigue
• Depression
• Anxiety
• Loss of appetite
• Pallor
• Numbness or tingling in the hands…