Facebook friends are filling my feed with photos of stunning sunrises that they are seeing on their way to work. Everyone marvels at them, yet all I can focus on is how we are about to be plunged into months of darkness.

It’s that time of year.

If you’re looking to get a head start on beating the winter darkness blues, order a SAD lamp – life-changing, let me tell you – stock up on vitamin D, and get ready to be the smug-yet-helpful expert in your friend group about this vitamin.

The fantastical world of how we get vitamin D

Vitamin D isn’t just one vitamin. It’s a quirky group of fat-soluble vitamins variants that are all cholesterol-like substances called sterols. Unlike other vitamins, D requires participation from almost the whole body. The skin, bloodstream, liver, and kidneys all play a part in forming fully active vitamin D.

On a bright, warm day, the UV light from the sun comes into contact with the cholesterol in our skin cells and together they form cholecalciferol. That newly created substance goes to the liver or kidneys and is converted into one form of vitamin D called calcidiol. It then goes – or stays – in the kidneys and poof! It’s converted into vitamin D3 – the most active form of vitamin D.

When we ingest vitamin D through supplements or food, it gets absorbed with other fats through the intestinal walls and makes its way to the liver. In the liver, a special protein – called the Vitamin D Binding Protein (DBP) – is made specifically to carry vitamin D through the bloodstream.

Functionally, vitamin D operates more like a hormone than a vitamin. Its structure looks similar to that of estrogen and cortisone – other hormones – and it relies on a feedback system for production in response to the body’s needs.

The many uses of vitamin D

Vitamin D plays countless roles. Some of the many health conditions that have been connected to vitamin D through research over the years include:

  • Supporting bone health. Vitamin D helps regulate calcium metabolism and the normal calcification of bones. It also helps to increase the absorption of calcium from foods we eat and supplements we take. Even when our calcium intake is adequate, without enough vitamin D, we don’t benefit from it as much as we could.
  • Preventing colds and flus. Research has found that vitamin D can affect our immune responses. A deficiency has been associated with an increased susceptibility to infection.
  • Decreasing the risk of dementia and Alzheimer’s disease. A study following over 1,600 healthy seniors found that those with a deficiency had a 53 per cent increased risk of developing dementia and a 69 per cent greater risk of developing Alzheimer’s disease.
  • Soothe stress and anxiety. Preliminary studies have found an association between vitamin D deficiency and symptoms of depression and anxiety in early pregnancy and in patients with fibromyalgia.

Getting enough vitamin D

Supplements – including vegetarian and vegan options – are readily available in health food stores and from online retailers. While the tendency and recommendation is often to megadose, caution should be exercised. As a fat-soluble vitamin, D will not be simply excreted if an excess is consumed. Toxicity is indeed possible and a real concern. Increase amounts gradually and with care.