Here in the northern hemisphere, the days are getting colder and shorter. The leaves are turning golden and red and there is a hint of frost in the morning air.
At this time of year, our metabolisms start slowing down and conserving energy for the winter ahead. It’s a time for warming and nourishing soups, stews and apple pies.
This time of year also heralds the decrease in daily UV rays from the sun, which means our ability to manufacture the wonderful vitamin D is drawing to a close. This is part of nature’s cycle, so why all the fuss about topping up our vitamin D levels?
What is Vitamin D?
Vitamin D is one of the few nutrients we make ourselves (for the most part). While we need to eat a balanced diet to ensure we get sufficient vitamins, minerals, protein and antioxidants, we were created to make our own vitamin D. The ‘manufacturing’ plant is our skin. We receive UVB rays from the sun and the cholesterol under our skin converts the rays into vitamin D. It is then transported to the liver and kidneys where it is converted into usable forms of vitamin D that different tissues need.
However, modern lifestyles mean that we spend more time indoors which means we aren’t able to make this key nutrient. In addition, we are now more cautious of over-exposure to the sun, so when we are outdoors, we are well covered up with clothes and/or sunscreen.
Why do we need it?
Perhaps the fact that we are designed to make our own vitamin D indicates how important it is for our overall health – we’re able to make it regardless of how much food there is available to eat!
Vitamin D is required for the proper absorption of calcium, which makes it essential for strong bones and healthy teeth, and to prevent rickets. Therefore, in order to maintain healthy bones and avoid possible osteoporosis in the future, you need to have adequate levels of vitamin D as well as adequate calcium.
However, vitamin D is critical to our health in more ways. Research conducted over the last few years indicates that vitamin D deficiency may be associated with a number of illnesses and conditions. These include:
- SAD (Seasonal Affective Disorder), also known as ‘winter blues’, symptoms of which include depression, lethargy and anxiety
- Poor immunity (frequent illness)
- Multiple sclerosis
- Cardiovascular disease
Many of these conditions are more prevalent in the northern hemisphere, possibly due to lower levels of UVB rays during the year. Levels of vitamin D deficiency are also highest in the northern hemisphere, particularly in Europe.
Some research has shown that every cell in the body has a vitamin D receptor, which suggests that it may be required for way more essential processes than we currently know of.
Who needs it most?
It is now widely accepted that people of all ages need adequate vitamin D.
This means that even pregnant mothers need to ensure they have enough for themselves and their baby – particularly if the last trimester falls in winter.
Growing children and teenagers also need adequate levels to keep them healthy, achieve peak bone mass and prevent chronic illnesses down the road. In fact, if a young person’s diet is full of processed foods and soda, and they are spending longer indoors on devices or watching TV, then they are doing even more damage to their immune and skeletal health, so adequate vitamin D is imperative.
Adults and the elderly also need to maintain good vitamin D levels. Conditions such as osteoporosis are a long time in the making – keeping on top of your health throughout childhood and adult life is really your best insurance policy for a healthy and vibrant old age. Furthermore, as we age, our skin becomes less efficient at producing vitamin D, so the elderly need to pay particular attention to their levels.
It’s also important to remember that the darker your skin or the higher your BMI, the more vitamin D your body requires.
How can we get it?
The best way to get vitamin D is to make it yourself, through sensible exposure to the sun (that’s the way nature intended!).
It is generally recommended to get 20 minutes of exposure (without sunscreen) daily in order to make and store sufficient levels of vitamin D for optimum health.
I stress optimum health, because RDA guides will prevent you from being deficient. When you’re deficient, you can start to manifest health problems, so you really want to have levels that are above the baseline for deficiency!
Of course, over-exposure to the sun can cause problems, so be sensible. 20 minutes at the hottest times of the day can send some fair-skinned types into lobster territory. You know your skin – if you can do 10 minutes in the morning and 10 minutes at say, 3pm, then that’s fine. Ensure you have your arms and legs exposed for maximum absorption. But if you can only nip out of the office during lunch, then just roll up your selves and soak up as much sunshine as you can. Sensibly.
Now, sunbeds are a source of UVB rays and are recommended by many as a *safe* way to top up your vitamin D levels if sun exposure is not an option. However, if you are considering this option, I would caution you to ensure that you only stay under the lights for the shortest time possible to manufacture some vitamin D.
You can get some vitamin D through food. The best sources include herring, oysters, salmon, trout, mackerel, sardines, mushrooms and organic/free range eggs.
However, you generally will only be able to get about 10% of the vitamin D you need through food.
That’s why a good supplement in the winter is a good option for those with low levels. A supplement with the active D3 is the best and should be taken with a meal, as vitamin D needs fat to be absorbed.
So, in summary:
- More and more studies are showing that vitamin D is essential for good health and prevention of disease
- Many in the northern hemisphere are vitamin D deficient (due to lower exposure to UVB rays)
- You need to ensure that you get adequate exposure to the sunshine when you can
- Eat vitamin D-rich foods to top up
- Consider taking a vitamin D3 supplement if your levels are below optimum.
- Sun exposure times will vary depending on skin pigmentation and weight. An average of 20 minutes is recommended, but this could be more depending on your individual requirements.
- Women who are pregnant or of child-bearing age and young children should not eat more than 2-3 portions of oily fish per week in order to reduce exposure to heavy metals.