Winter season is a time when your immunity needs a helping hand. And if you think adding vitamin C rich foods and supplements to your diet can help, you are, of course, right. But have you also thought about the benefits of maintaining your vitamin D levels within a healthy range?
Having to deal with recurrent bouts of flu and respiratory tract infections is pretty common during dark winter months, not to mention the down-trodden spirits, seasonal affective disorder, muscle stiffness and fatigue. Vitamin D can help in a number of ways to make sure you are able to overcome these challenges and sail through the winter months with ease. Vitamin D is not all about healthy bones. With the help of recent research, the role of the sunshine vitamin is becoming increasingly clear.
You certainly need vitamin D to keep your bones healthy as it helps absorb calcium and phosphorous from your food. But you also need it to fight infections and allergies, prevent the risk of autoimmune disorders, maintain healthy pregnancy, prevent the risk of age-related macular degeneration and so much more. It even plays an important role in keeping your emotional well-being, something that takes a huge hit during the dark, freezing winter season when there is little or no sunshine -depending on where you live.
Vitamin D, indeed, plays a bigger role in keeping you healthy than you may have thought. The good news is you can easily make your own vitamin D with sensible exposure to sunlight. Sadly, nowadays, we are getting little or no sun exposure and it is turning out to be one of the main reasons why vitamin D deficiency is so common in people across the world.
And what about winter months? Does this season make you more vulnerable to develop vitamin D deficiency? And how do you get enough vitamin D in winter? Let’s discuss this issue.
Vitamin D in winter
Studies show that vitamin D levels vary with seasons and tend to drop in winter months.  And there is substantial evidence showing that people who live in higher latitudes are typically low in vitamin D. And this situation gets worse in the months from October through March. This phenomenon is known as ‘vitamin D winters’, lasting for about four to six months in the northern hemisphere.
What happens is that:
- Your skin needs sunlight to make vitamin D
- But you can only make vitamin D with the help of UVB rays
- You get UVB rays at a particular time of the day and this happens when the sun is higher than 45 degrees above the horizon.
At places that lie at a latitude higher than 37 degrees North or South of the equator, the sun is below 45 degrees for most of the day during winters. UVB rays are stronger and more direct near the equator. If you live near the equator, the sun is mostly at the angle where it allows for easy absorption of sufficient UVB rays. The further you are living from the equator, the more time you need in the sun to make healthy levels of vitamin D. This means you have a very small window when your body can make vitamin D. And then there is an additional issue of not stepping outdoors in winters, when it is freezing outside, which compounds the problem. Furthermore, clouds, glass, ozone issues and pollution also block the UVB rays from coming through.
You are making vitamin D during sun exposure when your shadow is shorter than you really are. If your shadow is taller than your height, this means the sun is lower than 45 degrees, and not an ideal situation to make vitamin D due to lack of UVB rays.
People living in Northern Europe are at an increased risk of developing low vitamin D status, especially in winters. Of course, there are many other reasons why you may develop vitamin D deficiency. Most importantly, both adults and children are increasingly spending more time indoors.
Whether we blame it on longer working hours, a fear of skin cancer, excessive use of sunscreen or spending more time on smart phones and laptops, the truth is that we all are making less efforts to step out and feel bright, cheerful sunrays.
Unfortunately, lack of sun exposure is not only causing vitamin D deficiency, but it is also contributing to a lot of situations that are impacting your health. It is adversely affecting your bones, hormonal balance, mental and emotional health, sleeping pattern and immunity. Studies also show that people who get more exposure to sunlight in their adolescent years are at a reduced risk of developing myopia or near-sightedness.   And in many cases, sunlight offers health benefits that go beyond its role in vitamin D production. For example, one study found that UV light increases the activity of T cells, white blood cells that specialize in hunting and destroying harmful micro-organisms.  T cells can even destroy cancer cells.
Other factors that lead to poor vitamin D levels include:
- People with kidney or liver dysfunction
- People on statin drugs (statins block the synthesis of cholesterol in the liver, and you need cholesterol to make vitamin D)
- Dark skin
- Strict vegetarian diet
- Clothes that prevent healthy sun exposure (this could be due to occupational or cultural requirements)
Vitamin D deficiency and magnesium
There is another important factor that makes your vitamin D levels go south: magnesium deficiency. Magnesium is an extremely important mineral and like vitamin D, its role in your overall health is poorly understood. You need magnesium to facilitate hundreds of bio-chemical reactions in the body. You need magnesium to make energy, regulate calcium levels, synthesize and repair DNA, and produce glutathione. While its role in reducing painful muscle cramps is quite well-known, magnesium is quite helpful for people with insomnia, depression, anxiety and PMS.
Well, it turns out that you also need magnesium to utilize vitamin D. Unfortunately, this is something most doctors would not bother telling you. They would prescribe high doses of vitamin D to correct your vitamin D deficiency but fail to highlight that you won’t be able to properly use this vitamin D if you don’t have healthy levels of magnesium. Just like you need vitamin D to absorb calcium and vitamin C to absorb iron, you need magnesium to absorb vitamin D.
This is how nutrients in your body work together and the reason why there is so much emphasis on a healthy, balanced diet that is loaded with all kinds of vitamins, minerals and antioxidants that work hand in hand to offer comprehensive health benefits.
So, whether you are making vitamin D with sunlight or getting it through supplements, magnesium converts this vitamin D to calcitriol – a form that your cells actually use. Secondly, nearly all enzymes that are involved in metabolizing the sunshine vitamin need magnesium to function. What happens when you are taking a high-dose vitamin D supplement as usually prescribed by your doctor, but you don’t have enough magnesium? Your body would draw the needed magnesium from tissues like bones and muscles, where it is primarily stored, leading to a further deficiency. Result? You are more likely to experience symptoms like muscle cramps, twitching, angina pain and irregular heartbeat. These are all signs of magnesium deficiency.
One must consider that magnesium deficiency is one of the main reasons why some people don’t get their vitamin D levels up despite taking vitamin D supplements.
Vitamin D deficiency and risk of certain disorders
One of the most well-known side effects of low vitamin D level is weak bones. It is quite obvious, as you need vitamin D to absorb calcium. Low levels can cause rickets in children and osteoporosis in adults – leading to weak, brittle bones. What else?
Well, vitamin D deficiency has been linked to a slew of many other health problems. Low levels are associated with an increased risk of various auto-immune disorders including multiple sclerosis, rheumatoid arthritis, lupus, thyroid disorder and irritable bowel syndrome, certain types of cancers, diabetes, allergies, asthma, wheezing disorders, infections, heart disease, poor pregnancy outcomes, depression and poor cognitive functions.
How is that possible? Research shows that almost every cell of your body has receptors for vitamin D. These vitamin D receptors, when activated by vitamin D, can regulate various genes. For example, when vitamin D activates receptors present in the immune cells, they turn on genes that make antibiotic proteins that fight infections and disease. This is one mechanism through which vitamin D boosts your natural immunity. Similarly, you have vitamin D receptors in intestines, brain, heart, bones, lungs, thyroid gland and other tissues. This is how vitamin D plays such a diverse role in your health.
A quick guide to get enough vitamin D in winter
It is true that sunlight exposure and supplements are the best sources to achieve healthy levels of vitamin D in the blood. What about foods? Fish such as salmon, tuna and mackerel are among the richest sources of vitamin D through food, but not enough to maintain healthy levels without sunlight or supplements. Fish liver oils, egg yolk, mushroom, cheese, shrimp and fortified foods such as milk, orange juice and cereals are also a good addition to your diet. But the fact remains that you can’t get substantial amounts through diet alone, and it would be wrong to simply rely on foods to increase your vitamin D levels.
You need to step out in the sun (at the right time and for the right duration), and without sunscreen. In addition, you must take vitamin D supplements, especially during winter and for people who live at a higher latitude. And even if you are living in an area that receives plenty of sunshine, it is best to expand your sources of vitamin D.
Living at a latitude higher than 37 degrees? It is easy to make vitamin D naturally with sensible sun exposure. A walk of 15-20 minutes in the sunshine (during the day, mostly between 10.00 am to 3.00 pm should help. Again, you know you are making the most vitamin D when your shadow is shortest during the day.) But what exactly is sensible sun exposure?
On average, spending about 15-20 minutes in the sunshine three to four times in a week is all you need to make good amounts of vitamin D. Turning a slight shade of pink is a fair indication that you have stayed enough, beyond which may give you a sun tan or a sun burn. The duration of sun exposure to make vitamin D also depends on skin colour. If you have fair skin, about 10 minutes in the sun should suffice. However, people with a dark skin tone may need up to 30 minutes or longer in the sun to make that kind of vitamin D.
And as we noted, the time of the day does matters. You need UVB rays to make vitamin D within the body and this type of sunlight is only available during a certain part of the day. And if you have a history of skin cancer or you are at a risk of developing skin cancer, it is always best to avoid sun exposure. Taking supplements is often the best route to avoid vitamin D deficiency in this case.
But how do you satisfy your vitamin D requirements when days are shorter and there is not enough sunshine? It is best to take a high-quality liposomal vitamin D supplement to maintain your vitamin D levels and beat the winter blues. And make sure you also increase your intake of magnesium as it will help your body to regulate the levels of calcium as well as vitamin D.
Don’t underestimate the power of eating a well-balanced, varied diet, whether it provides substantial amounts of vitamin D or not. Foods such as fatty fish, eggs and mushrooms not only provide some amounts of vitamin D (something is always better than nothing), but they are also a very good source of other vitamins and minerals that you need for your overall health, be it summer or winter.
Have you had your vitamin D levels checked lately?
- Kroll et al. Temporal Relationship between Vitamin D Status and Parathyroid Hormone in the United States. PLoS One. 2015.
- K.M Williams et al. Association Between Myopia, Ultraviolet B Radiation Exposure, Serum Vitamin D Concentrations, and Genetic Polymorphisms in Vitamin D Metabolic Pathways in a Multicountry European Study. JAMA Ophthalmol. 2017
- Tideman et al. Low serum vitamin D is associated with axial length and risk of myopia in young children. Eur J Epidemiol. 2016
- Phan et al. Intrinsic Photosensitivity Enhances Motility of T Lymphocytes. Scientific Reports. Article number: 39479. 2016