- cannot be made by the human body itself
- they need to be obtained via the diet
- are needed to maintain many vital functions, so symptoms of deficiency are very diverse and unspecific, in the case of vitamin B deficiency symptoms are often psychological in nature
Not all the vitamins we swallow also reach the blood, the capacity of the digestive tract to absorb them is limited.
They are also obstructed by:
- Inflammation of the gastro-intestinal mucosa
- Medicines to protect the stomach
- Incorrect composition of the intestinal flora (dysbiosis)