Vitamin A and viral infections

Vit A is needed for the integrity and defence of our skin and the mucous membranes that line our mouth, nose, gut and lungs. Without this we are vulnerable to attack by viruses and other microorganisms. There are tiny hair like projection in the windpipe called cilia that waft any particles we have breathed in up and out of the lungs. They too depend on vitamin A. Some viruses enter the body through the surface of the eye. Vit A helps to lubricate it and defend it from infection. It is essential in the formation of mucus, again a protective layer, against attack by germs. It also plays a role inside the body supporting our immune system. It is needed for our immediate response to invaders. White cell such as neutrophils and macrophages are our front line troops that instantly go after what is recognized as foreign. Real vitamin A is called retinol. This is only available from animal foods. The richest sources are liver, eggs, cod liver oil and high fat dairy. It is a fat soluble vitamin and is best absorbed with fat. Many people think that carrots are a good source of vit A and that they help with night vision. Indeed there are about 600 compounds called carotenoids, named after carrots, that can undergo conversion by the body to vit A. These compounds are termed pro-vitamin A. In some individuals this conversion is poor. In about 25% of the population have a marked reduction in the ability to convert the carotenoids to real vit A. Is it worth the risk? Carotenoids are not an essential food as a result.