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This week, I’m continuing my focus on nutrition and immune function and discussing the important contribution of Vitamin A to immunity.
Vitamin A : What’s it All About?
Vitamin A is essential for immune function and is euphemistically known as the anti-infective vitamin due to its powerful infection-preventing properties.
Vitamin A is an essential vitamin, which means that humans are unable to manufacture it themselves and must obtain it through the diet.
There are 2 forms of dietary vitamin A, namely:
· Retinoids : these are found in animal food sources, for example liver, cod liver oil, cow’s milk, fish (particularly prawns, salmon, halibut, scallops, sardines), egg, cheese and yoghurt
· Carotenoids: these are found in plant sources, for example sweet potatoes, carrots, spinach kale, bell peppers, tomatoes etc. In fact, any colourful fruit or vegetable will supply a good source of the Vitamin A carotenoids.
The two forms of Vitamin A are chemically different and exert different effects in the body, but both are important for immune function. Under certain circumstances carotenoids may be converted to retinoids in the body, but the conversion rate of this depends on the health status of the individual and their genetic predisposition.
The retinoids are important for skin health which is our first line of defence against bugs and germs since the skin acts as a barrier to keep infection out of the body. Retinoids are also important to maintain the health of our digestive and urinary tracts and also our airways by forming a moist substance which coats the linings of these systems and prevents the adhesion and infiltration of bacteria and viruses.
The carotenoids are also important since they increase the number of infection-fighting cells in the body and also act as potent anti-oxidants which protect our cells against the damaging effects of free radicals, which, if left unchecked, can cause a number of serious diseases.
The Ear, The Nose and The Throat of It!
Even a mild deficiency of Vitamin A is linked to a higher incidence of coughs, colds and ear infections, and is also implicated in autoimmune disease (e.g. Crohn’s Disease, Rheumatoid Arthritis) so it’s important to pay attention to your vitamin A intake in order to support optimal immune function. High levels of vitamin A deficiency are linked to extreme impairment of immune performance with loss of protective mechanisms to fight infection.
Maximise to Optimise
To maintain a healthy immune system, Vitamin A requirements are best obtained from food sources, as opposed to supplementation. I advise eating good quality sources of protein (e.g. grass-fed meat and poultry, wild salmon, small oily and unfarmed fish, free range eggs) and a wide variety of colourful vegetables (and a little fruit) to optimise your Vitamin A intake. Since vitamin A is a fat- soluble vitamin, it requires the presence of fat in the gut for optimum absorption, so always eat vitamin A-rich foods with some fat (e.g. carrots with a knob of butter) to obtain maximum nutrition.
There are a number of caveats regarding vitamin A consumption. Pregnant women should avoid excess intake of retinoid foods since high consumption is linked to birth defects. There is also on-going debate whether supplementation with retinoid forms of vitamin A leads to osteoporosis in older adults, hence my advice to stay safe and obtain vitamin A intake from food sources rather than supplements.
Juliet Schaffer from Evolve Nutrition is a fully qualified and accredited Nutritional Therapist with a Bachelor of Science degree in Nutritional Medicine. If you are seeking nutritional advice regarding a specific health concern, or would like guidance for achieving and maintaining a health-promoting diet, take the option of a free 20 minute telephone consultation to see how professional nutritional advice can benefit you. Check out Evolve Nutrition’s website at www.evolve-nutrition.co.uk for contact details or phone 01279 726640 to book a free initial telephone consultation.
Juliet Schaffer, Nutritionist, Evolve Nutrition