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Boost Your Immune System with Vitamin D During Darker Days

by sahodd85

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As the days get shorter and colder, you may find yourself wearing a few more layers or maybe taking a couple less or shorter walks than usual. This is a totally natural response to living in a cold climate; it’s our form of winter “hibernation.” But did you know that our slow shift to the indoors can strip our body of the beneficial effects of sun exposure?

Yes–excessive sun exposure can contribute to damaging health effects like an increased risk for skin cancer and cataracts, or making your skin age faster. However, our reduced sun exposure through colder months also gives us less access to the sun’s health promoting benefits. The benefits of sun exposure include things like:

Vitamin D is a powerful ally in supporting our physical and emotional health. And so, what steps can we take to keep our vitamin D supplies up through the cold and dark seasons?

What vitamin D is, where we get it from and why it’s so important for our bodies

Vitamin D is a nutrient that is essential for building and maintaining our health in many ways. It is the only vitamin that is converted into a hormone in our bodies. It’s fat-soluble, and so it dissolves in fats and oils and can be stored in our bodies for a long time.

It’s unique because it can be produced or “synthesized” by our bodies after exposure to the sun’s ultraviolet rays. The sun emits ultraviolet B (UVB) radiation that penetrates and is absorbed into our skin. UVB stimulates our bodies to produce or “synthesize” vitamin D3. Vitamin D3 is produced in animals, whereas you can find vitamin D in plants, phytoplankton, yeast and fungi. Vitamin D3 is more effective at raising your vitamin D levels than vitamin D2. But, I refer to both forms as vitamin D throughout this post because the function of D2 and D3 is almost the same.


Ultraviolet radiation

The best source of vitamin D is from the sun. The larger the area of skin we exposure, the more vitamin D3 we produce. So as the colder months roll in and sunlight levels decrease, our bodies have less and less opportunity to make vitamin D3.

There are various factors that may affect how much vitamin D we get from ultraviolet light, like the season, time of day, latitude, altitude, air pollution, sunscreen use, and aging. Some sources say that people with darker skin types, such as those with African descent, may be vulnerable to vitamin D deficiency in the northern hemisphere. This would be because melanin absorbs UV radiation from the sun, and therefore reduces exposure to UVB. Other research shows that people with darker skin types don’t always suffer from deficiency symptoms. For instance, one study shows that people with African descent actually tended to have stronger bone density.

The jury is still out on the interplay between factors that affect our synthesis of vitamin D.


Food sources

There are only a few foods where small amounts of vitamin D occur naturally. Therefore, food is an insignificant source of vitamin D.

Common natural sources of vitamin D3 include fatty fish like salmon, rainbow trout and mackerel, and egg yolks. Other natural sources of vitamin D2 include shiitake, morel and chanterelle mushrooms. Meats such as pork, lamb, beef, veal, liver and poultry can also include vitamin D3, but at minimal levels and to a varying degree.

Many countries add vitamin D to foods to “fortify” them. In Canada, it’s mandatory to add vitamin D to cow’s milk and margarine. It can also be added to goat’s milk, fortified plant-based beverages like soy milk and calcium-fortified orange juice, as well as yogurt, cheeses and breakfast cereals. In other countries, like the United Kingdom, cow’s milk is not fortified with vitamin D. Check with your local health agency before relying on fortified foods as a source of vitamin D.


What does it do for us?

Vitamin D keeps our bones and teeth healthy and dense by increasing calcium and phosphorus absorption through our intestines. Having a healthy supply helps to ward off diseases like rickets which causes bone deformities (in children), bone pain caused by osteomalacia and bone thinness caused by osteoporosis (in adults). It also regulates the amount of phosphate in our bodies, which helps keep our muscles healthy.

Vitamin D enhances your natural immunity to illnesses such as respiratory tract infections by encouraging the expression of defensive molecules. These molecules, known as antimicrobial peptides, help your immune system to protect you from invading bacteria, yeasts, fungi, viruses and foreign cells.

Your mental health can benefit from maintaining your vitamin D supplies. The hormone in vitamin D, calcitriol, activates neuron receptors that help us to manage our behaviour and emotions. Vitamin D tells your body to release neurotransmitters like dopamine and serotonin. Dopamine makes us feel good; it’s connected to pleasure and satisfaction and is part of our reward system. Serotonin also makes us feel happy, and contributes to emotional stability, lower anxiety, tranquillity, focus and energy.


4 ways to boost your body’s vitamin D supply


Your body will thank you for taking extra steps to stay healthy going into the fall and winter seasons. The goal is to maintain your vitamin D stores to help your immune system ward off those seasonal colds and illnesses, and keep your mental health in good shape. There are lots of ways to do it. And so, we explored how to get more sun exposure, vitamin D-rich foods, supplement with vitamin D and use light therapy to keep your system humming.


1. Eat a meal with vitamin D rich foods

Although food is not a significant enough source of vitamin D to meet your daily intake needs, it can still be a healthy contributor. Try adding in meals and snacks that use vitamin D-rich ingredients like:

  • Oily fish: Salmon, rainbow trout, swordfish, sturgeon, whitefish, mackerel, tuna, halibut, herring, sardines, rockfish, tilapia, flounder and sole
  • Egg yolks.
  • Fortified foods: Cow’s milk (in Canada), goat’s milk, plant-based beverages, orange juice, yoghurt, cheese and breakfast cereals.

There are lots of different meals that feature these star ingredients. Here’s how a vitamin D-rich meal plan could look for a typical day:

  • Breakfast: Dig into a bowl of cereal or cook some oatmeal and top it off with fortified soy or almond milk. Boil up an egg to eat on the side with some toast, and grab a glass of fortified orange juice.
  • Lunch: Sauté up this simple vegetarian teriyaki dish with tofu and shiitake mushrooms, and eat with a side of steamed watercress (which is high in vitamin C).
  • Dinner: My mom used to make us Jamie Oliver’s Kedgeree recipe as kids; a rice-based dish with curried egg and fish which was a fan favourite. Just substitute the haddock for any of the oily fishes mentioned in the list above, like salmon or swordfish.


2. Consider taking a vitamin D supplement

People of all ages may benefit from supplementation, from infants to older adults. Most people should be able to get their vitamin D intake from the sun between late March/early April to the end of September in northern and far southern climates. This means that you may want to consider supplementation between October to March each year.

While vitamin D can support your health, over time taking more than recommended does can have the opposite effect. Taking too much vitamin D can cause hypercalcaemia where calcium builds up in the body. This can lead to weakened bones and damage to the heart and kidneys.

If you’re interested in taking a vitamin D supplement, speak with your healthcare professionals. Many local health agencies also provide information on how to take supplements safety. Here are a few links to get you started:


4. Catch some extra rays with light therapy

While we normally get our UV radiation from the sun, during darker times of year we may want to get it from artificial sources. In comes light therapy–where sun lamps exposure people to UV radiation to raise their vitamin D levels. Light therapy can be used to treat vitamin D deficiency and conditions such as rickets, lupus, psoriasis and vitiligo.

Boosting your vitamin D levels with light therapy may also create happy side effects. Studies have shown that UV light therapy may improve your mood, depressive symptoms and seasonal affective disorders.

Before opting in for light therapy, discuss it with your healthcare professionals. There are lots of online resources too that can help you pick the right light therapy box for you.


5. Get outside even when it’s chilly out there

Staying active outdoors at all times of year is super important for your body and mind on so many levels. However, winter UVB wavelengths may be insufficient to simulate enough vitamin D production to meet your daily needs. Getting sun exposure on winter days can still help you to maintain your vitamin D levels though. And so we brainstormed some ways to enjoy a chilly winter day.

  • Be prepared to brave the cold. I like to wear merino wool base layers in the winter because it’s thin, breathable and warm, and soft enough for my sensitive skin. Try these under your pants and sweaters.
  • Keep active outdoors. The cold weather can be a great time to go for walks, hikes or fat tire bike rides. Or to try out a new outdoor activity like skating, snowshoeing, cross country skiing or even horseback riding.
  • Stay hydrated. It’s easy to let drinking water slip your mind when it’s cold outside. But, winter dehydration is more common than you think. I like to keep an insulated mug full with a hot drink to sip on.

If you have a gastrointestinal symptoms or a syndrome like IBS, cystic fibrosis and gastric bypass surgery, you may be more likely to have a vitamin D3 deficiency. Talk to your healthcare professionals to see if supplementation or light therapy may be the right option for you.


Conclusion: Keep your vitamin D supplies up to stay healthier during the darker days

It’s important for your health to maintain your body’s vitamin D supply throughout the year. So, consider taking extra steps to support your body and mind.

There isn’t one magic ticket to increase your vitamin D during darker and colder months of the year. Instead, consider trying a combination of approaches including: going outside during the colder months, eating vitamin D-rich foods, taking vitamin D supplements or using UV light therapy. Always consult with your healthcare professionals before introducing a new supplement or therapy into your life.

Do you have any other strategies for keeping your vitamin D supplies up throughout the year? Let us know!

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