As winter approaches and the days become shorter, many Canadians will find themselves daydreaming about beach vacations.

This longing, it turns out, may not be psychological, but biological.

In recent months a number of studies have been published pointing to Vitamin D's crucial health properties.

Although this essential nutrient comes from some foods, most of it is made when skin is exposed to sunlight.

Canadians, with their long and cold winters, tend to become particularly deficient of the "sunshine vitamin." Some experts believe that 80 per cent of Canadians have inadequate levels.

A lack of Vitamin D in the body has been linked to poor bone health, rickets and -- more recently -- weakness or pain in joints and muscles, regardless of age.

The findings are prompting many health experts to prescribe Vitamin D supplements during the winter months.

For many patients, the vitamin boost is making a critical difference in their daily life. Julie Trottier knew she had something more serious than a case of the winter blahs.

"I was always tired...I'd have no energy...and I knew that wasn't normal," Trottier told CTV News.

She eventually went to her doctor and found out she had seriously low levels of Vitamin D in her blood and was prescribed supplements.

"I feel like myself, I have the energy to do stuff that I want to do," Trottier said. "It has absolutely 100 per cent improved the quality of my life."

Although more research needs to be done, health experts are impressed with this previously overlooked nutrient.

"There are so many little lotteries where Vitamin D is winning ... confirming it is a big win for public health," Dr. Reinhold Vieth from Toronto's Mount Sinai Hospital told CTV News.

Vieth hopes more health care professionals will begin promoting the benefits of the nutrient.

"It's a frustrating thing because nobody feels vitamin D is worth it, almost as if 'I haven't heard about it, it can't be important.' It's tough to get the message out," he said.

Nutritional consultant Aileen Burford-Mason also wants to get the word out.

She regularly advises clients to take vitamin D pills, particularly during the winter.

"It's quite extraordinary the difference in some people's health when you give them the Vitamin D they have clearly been missing," Burford-Mason told CTV News. "You start to ask why aren't we doing this for everyone."

The supplement can help from everything from depression to common joint pain.

"The most startling fact is when they do have stiffness and joint pain and that disappears," Burford-Mason said.

New studies are linking high levels of Vitamin D to a variety of health benefits including:

• Lower rates of bone fractures in patients with osteoporosis
• Lower rates of breast, colon and prostate cancer
• Improved survival in those with lung cancer

According to Burford-Mason, studies are also showing that people need more Vitamin D than previously thought.

Most multivitamins contain 400 International Units of Vitamin D, though Mason suggests most people need 1,000 I.U. or more a day.

However, the proper dose is different for each person.

"You have to work with a knowledgeable practitioner and doctor to ensure that you get an adequate blood level," Burford-Mason said.

To ensure adequate levels of Vitamin D all year round, doctors recommend people visit their doctor for an annual blood test.

With a report from CTV's Avis Favaro