At this time of year, many people think more about their well-being but, according to medical experts, you may want to start taking an essential pill. NHS GP Doctor Shireen recently urged people to consider adding it to their daily routine, as it can have a vital use, especially during the winter months.

Doctor Shireen insisted that everyone should be taking it right now, as it could make a significant difference to their health. She issued the expert advice in a candid video, and told people exactly what they need to know to boost their immune systemsin a simple way.

It's not the first time she's opened up about how essential it is either. Back last year, she also spoke about the supplement's major benefits.

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Doctor Shireen said: "I'm an NHS GP, and today I'm going to tell you about one supplement that everybody should be taking right now. When you're deficient in this vitamin, it's not often a really obvious thing.

"It's just, it presents very subtly. So like tiredness, body aches, just feeling run down, getting more coughs and colds than normal [and] maybe a little bit of hair loss as well.

"It's vitamin D deficiency. Now we, as doctors, are always taught to advise food first, which is fine if we're living a very unbusy life, able to eat everything that we want to eat but, even with the best diet in the world, you're never going to get enough vitamin D from your diet alone.

"We need to supplement it because the place we mainly get it from is the sun and sunlight and obviously right now, during the winter months, we do not see enough sunlight to be able to maintain the vitamin D levels that we need to maintain.

"Check your levels but, even if you don't check your levels, everyone should be taking around 800 to 1,000 units of vitamin D a day from October to March, but also throughout the year if you work indoors."

According to the doctor, this is the key to boosting your immune system at this time of year. It's a really simple rule to implement, and it can be taken in the form of a pill or capsule.

Little you may know, vitamin D is an essential nutrient that works to aid healthy bones, teeth and muscles by aiding the absorption of calcium and phosphorus. As well as being produced by the skin upon exposure to sunlight, it can also be obtained from specific foods, including oily fish and fortified products or supplements.

A deficiency in vitamin D can cause bone problems like rickets in children and osteomalacia in adults. In addition, it can also impact immune function.

The NHS website states: "Government advice is that everyone should consider taking a daily vitamin D supplement during the autumn and winter. People at high risk of not getting enough vitamin D, all children aged one to four and all babies (unless they're having more than 500ml of infant formula a day) should take a daily supplement throughout the year.

"There have been some reports about vitamin D reducing the risk of coronavirus (Covid-19), but there is currently not enough evidence to support taking vitamin D solely to prevent or treat Covid-19.

"During the autumn and winter, you need to get vitamin D from your diet because the sun is not strong enough for the body to make vitamin D. But, since it's difficult for people to get enough vitamin D from food alone, everyone (including pregnant and breastfeeding women) should consider taking a daily supplement containing 10 micrograms of vitamin D during the autumn and winter.

"Between late March or early April to the end of September, most people can make all the vitamin D they need through sunlight on their skin and from a balanced diet. You may choose not to take a vitamin D supplement during these months."

More information about vitamin D can be found on the NHS website. Anyone concerned about taking a supplement should speak to their GP before making any changes.