Snapshot series 8: Water soluble Vitamins

Water-soluble vitamins perform a wide range of important functions, including the extraction of energy from food, cell signalling, synthesis of DNA and conduction  of nerve impulses. Water-soluble vitamins comprise nine compounds – vitamins B1, B2, B6, B12, C, niacin, folate, biotin and pantothenic acid – distinguished by their chemistry and function. They are required regularly in small amounts in the human diet as they are not stored in the body; excess intake is removed by the kidneys. Symptoms of deficiency may occur if a diet lacks any one of these vitamins. 

For example, a diet lacking in vitamin C can lead to the development of scurvy, characterized by impaired wound healing, joint pain, tiredness and shortness of breath; a diet lacking in vitamin B12 may lead to anaemia and degeneration of the spinal cord. It has proved difficult to know exactly how much of each vitamin is required daily to stay healthy. Early experiments (that would be considered unethical today), systematically deprived human volunteers of vitamin C to determine how much of this vitamin reversed symptoms of scurvy.

 Such studies formed the basis of dietary reference values for water-soluble vitamins.  

A varied diet that includes fruit and vegetables, cereals, meat, fish and dairy products is likely  to satisfy a person’s requirements.

Claims that high-dose supplements of watersoluble vitamins confer special health benefits, or help us to live longer, are generally not well-founded. 

Although people with poor diets or higher requirements may need vitamin supplements to prevent symptoms of deficiency, supplement use is most common amongst healthy people consuming a varied and nutritious diet.

 Indeed, very high-dose vitamin supplement use may have adverse health effects, including a possible increase in cancer risk.