Seasonal colds and flu can be combated by boosting your immune system with vitamin D3 and are little to do with winters spent indoors with the central heating on, says Dr Graham Matthews. 10 amazing facts about vitamin D that just might stop you sneezing: Not a vitamin Vitamin D is technically a hormone not vitamin and, like all hormones, it has extensive influence over trillions of cells in the human body. Overlooked Vitamin D3 (the vital form of vitamin D) was only identified around 100 years ago and our understanding of its power was overlooked due to a lack of research. Rickets Medical experts previously only linked vitamin D3 to combating rickets, a condition largely associated with mid-20th century poverty. However, it’s now known that vitamin D influences almost 3,000 of our 25,000 genes. Its link in preventing cancer and other major illnesses could therefore be huge. Gloomy Britain In the USA it is estimated that over 50% of the population has a Vitamin D deficiency.(And if you think that it’s often sunny in the US, what does that say about vitamin D3 levels in the UK?) Limited D3 foods D3 deficiency occurs in part because it’s difficult to access this hormone from diet alone. Oily fish, red meat, liver, egg yolks and fortified foods (most fat spreads and some breakfast cereals) provide some vitamin D3. Cats and dogs In mammals, sunlight interacting with the oils within the fur produce vitamin D which is then licked and ingested. This may be a reason why our pets groom themselves so often. As hairless, clothed mammals, humans need other ways to get vitamin D so evolution has provided us with skin that makes this nutrient directly from sun exposure. Get out for lunch We all need to spend more time exposed to sunlight but it’s the UVB rays that we’re really interested in as these make vitamin D. These rays are best absorbed between 11am and 2pm when the sun is at its highest. Just 10 to 20 minutes per days generates sufficient vitamin D. Skin cancer UVA sunlight (the other kind) is detrimental to health and is responsible for the signs of ageing linked to sun exposure. UVA light is more prevalent when the sun is lower in the sky. Glass and even sun block filter out the good UVB but allows damaging UVA to pass through. Statistically indoor workers get more skin cancers than those that live and work outdoors. Fire up your immune system Vitamin D enables your body to produce well over 200 antimicrobial substances which are crucial in fighting infection. German researchers have found it increases your immune system by a factor of 3 to 5. Defend against viruses A robust immune system is the best defence against viruses including seasonal colds and flu. Optimising vitamin D levels is very important in this aim. Viral infections are notoriously difficult to treat medically and the only way to fight viral infections is to get your immune system to do it - vitamin D3 can help. Better than the flu vaccine A recent Japanese study showed that school children taking vitamin D3 supplements were 58 percent less likely to catch flu. That's a higher effectiveness than any flu vaccine can claim. Explore the proto-col nutrition range here. Graham is a Doctor of Chiropractic who has worked in successful clinics in Bath, Bristol and also Portugal for nearly two decades. Wellness Chiropractic is a drug-free health system based on natural health principles which treats all aspects of a person’s wellbeing, not just their bad backs. As a Doctor of Chiropractic, Graham’s extensive training includes neurology, orthopaedics, pathology, radiology, kinesiology and functional biochemistry. He lectures regularly across a wide range of wellbeing topics.