We’re not getting enough sun. And not just because we’ve had a few weeks of April showers in August. We’re just not exposing ourselves to sunshine enough to generate the health-boosting levels of vitamin D in our bodies we need to function.

So say scientists from McGill University in Canada, whose study found those born genetically predisposed to vitamin D insufficiency were twice as likely to have the neurological condition multiple sclerosis.

[Read more: How to be supplement savvy]

The possible link is just the latest in a series of health problems discovered to be connected to a lack of vitamin D – a vitamin so essential to our wellbeing that some experts have suggested it ought to be added to foods to protect our health.

Parents are already being advised by the government to give children under five vitamin D supplements to prevent conditions including rickets – which is on the rise, with 40% of children estimated to have vitamin D levels under the recommended amount.

[Read more: 6 ways to boost your vitamin D intake]

“Vitamin D is very important in maintaining a healthy body, says LloydsPharmacy pharmacist Alison Freemantle.

“It can be found naturally in sunlight, oily fish, eggs as well as fortified spreads, bread and cereals. Keeping yourself topped up with enough of the vitamin can aid prevention of Type 2 diabetes and hypertension.

“There has also been some suggestion that it can help Seasonal Affective Disorder, cold and flu prevention and generally help your immune system.”

Here are some of the conditions vitamin D deficiency has been linked to…

Osteoporosis

Vitamin D is needed to help the body absorb calcium and phosphate from our diet. These minerals are essential to keep bones and teeth strong. But just a mild to moderate vitamin D deficiency, can lead to bone pain and osteoporosis, which is a weakening of the bones that makes them more likely to break.

Osteoporosis affects around three million people in the UK, with some 300,000 receiving treatment for fragility fractures each year, according to the NHS.

Low mood

Seasonal affective disorder (SAD) and low mood in the winter months occur in part because our levels of vitamin D drop when the sun’s not up for as long.

“It is known that vitamin D has important roles in keeping our immune system healthy, and our bones and teeth strong,” says Dr Marilyn Glenville, nutritionist and author of The Nutritonal Health Handbook for Women.

“But there is also a possible link between reduced vitamin D levels and low mood in winter. Most nutritional therapists now recommend that adults take at least 1,000 to 2,000 iu of vitamin D over the winter months, so add an extra supplement if your multivitamin doesn’t already include this amount.”

Rickets

Known as osteomalacia in adults, this condition, which causes poor growth and bone deformities such as bow legs, was pretty much wiped out in the Western world, but is making a comeback in today’s children, partly due to them staying indoors more, as well as our fear of skin cancer.

But the NHS advises that the hands and face only need to be exposed to sunlight for about 15 minutes a few times a week during spring and summer to provide you with enough vitamin D.

Erectile dysfunction

The most common sexual problem among men can be caused by other health conditions such as diabetes and prostate cancer, but a study published last year in the Journal of Sexual Medicine found men with severe cases of erectile dysfunction had much lower levels of vitamin D than those with mild cases.

Dementia

Last year, a study published in the journal Neurology found the risk of dementia, including Alzheimer’s disease, was doubled for older adults with a vitamin D deficiency.

While the scientists couldn’t say the deficiency caused dementia, they found a definite association and believe the so-called ‘sunshine vitamin’ might help to clear plaques in the brain linked to dementia.