Why is vitamin D so important?
Vitamin D is important to stay healthy. Unfortunately, many people have a vitamin D deficiency. In the Netherlands almost 60 percent of people have a vitamin D deficiency and in many other EU countries the rates are comparably high. In the United States, an estimated 70 percent of people has a vitamin D deficiency. In this blog we discuss why vitamin D is so important and how you can make sure you get enough of it.
What does it do for our body?
Vitamin D is mostly important for our bone health. Most people think of calcium when they think of healthy bones, but vitamin D actually plays an important role in keeping your bones strong as well. Vitamin D helps absorb calcium from food and helps transport that calcium to the bones. A deficiency can therefore lead to fractures or other bone problems. For that reason it’s also important for your dental health. A severe lack of vitamin D can even lead to osteomalacia, which causes the bones to become weak and painful. A smaller deficiency can lead to osteoporosis.
In addition, vitamin D helps absorb phosphorus from food and contributes to a healthy immune system. It also helps to keep our muscles healthy so a deficiency can also lead to weaker muscles and muscle cramps. Furthermore, some research suggests that vitamin D might reduce the chance of getting certain cancers or depression. However, more research on this is needed.
Vitamin D from sunlight
The most important source of vitamin D is sunlight. When exposed to sunlight, our skin makes vitamin D by itself. The first humans lived near the equator and gained plenty of vitamin D through sunlight exposure. Also in areas further away from the equator, such as Europe, people used to be able to get enough vitamin D from sunlight. Nowadays, most people don’t spend enough time outdoors anymore. To make enough vitamin D, your head and hands need to be exposed to sunlight for 15 to 30 minutes every day between 11:00 and 15:00. When sunbathing, even a few minutes are enough to make your daily amount of vitamin D. Staying in the sun for longer does not lead to our skin making much extra vitamin D. Therefore, sunbathing for a long time is not recommended, especially as it’s also very bad for your skin.
As many people don’t spend enough time outside and there are also cloudy days, many people don’t make enough vitamin D from sunlight exposure. In countries such as the Netherlands, people with a light skin usually make about two thirds of the vitamin D they need from sunlight. The rest has to come from other sources, especially in winter. People with a darker skin need more sunlight to make the same amount of vitamin D and therefore need extra vitamin D from other sources.
Vitamin D from food
Vitamin D can also be absorbed from food, both from plant-based and animal products. Most animal products contain vitamin D, while plant-based sources are rare. Mushrooms can contain vitamin D if they’ve spend enough time in sunlight. Unfortunately, many mushrooms are grown in the dark and therefore don’t contain vitamin D. Luckily, there are plant-based products that contain added vitamin D, such as margerine, plant-based milks or other dairy and cornflakes. When a product contains added vitamin D, be sure to check whether this is plant-based or animal vitamin D. When it says vitamin D2, it is usually plant-based. When it contains added D3 or only mentions vitamin D, it’s often from an animal source, as that’s the cheapest source of vitamin D.
Vitamin D2 versus D3
The two best-known types of vitamin D are D2 and D3. D3 mostly comes from animal products and when it is added to a product, it’s mostly made from lanolin, also known as wool wax. To make this type of vitamin D, a sheep’s wool is cooked. The fat is then seperated from the wool and certain fats are isolated. By exposing these to UV light, they become vitamin D.
There is also plant-based vitamin D3 made from lichen. Unfortunately, this is much more expensive and is therefore mostly used in vegan products only. Vitamin D2 is almost always plant-based. Usually plant-based ergosterol is exposed to UV light to make vitamin D2 or it’s made by fungus. Vitamin D3 is absorbed by our bodies slightly better, but vitamin D2 also works fine. Especially when consuming a small dosis, there’s not much of a difference.
Supplements
As many people have a vitamin D deficiency, it can be a good idea to regularly take vitamin D supplements. Even when you regularly eat food that contains vitamin D and spend time outside, the chance of getting a deficiency is still quite high in areas such as Northern Europe, especially in winter. Certain groups in particular, such as young children, the elderly, pregnant women, people with a dark skin and people who don’t spend much time outdoors are advised to take vitamin D supplements
People need on average about 10 mcg of vitamin D. This can come from exposure to sunlight, but also from other sources such as a supplement. Especially in winter it’s a good idea to use a supplement. Some vegan dieticians advise vegans to take supplements of 15 to 25 mcg and most health organisations advise elderly people to use supplements of 20 mcg every day. Pay attention when you buy supplements to make sure they’re vegan. All vitamin D2 supplements are vegan, but most D3 supplements aren’t. Vitamin D is best absorbed in combination with fat or oil. It’s therefore best to take the supplement together with a meal.
The risk of too much vitamin D is very small. 100 mcg is considered the maximum safe amount of vitamin D per day. Only when people ingest too many supplements and exceed this amount, health problems can occur. When consuming the recommended daily amount, there’s no risk of any health problems. Long exposure to sunlight also doesn’t increase the risk of getting too much vitamin D in your body. Our body only makes the amount it needs and the skin doesn’t continue producing lots of vitamin D when you keep sitting in the sun.
Bronnen:
Vegan Wiki, Voedingscentrum & Gezondheidsraad
Tripkovic, Lambert, et. Al. (2012) “Comparison of Vitamin D2 and Vitamin D3 Supplementation in Raising Serum 25-hydroxyvitamin D Status: A Systematic Review and Meta-analysis”. American Journal of Clinical Nutrition; 95(6): pp. 1357–1364.
Boonman-de Winter, Leandra J.M.; Albersen, Arjen; Mohrmann, Karin; Bakx-van Baal, Carla M.A.C.; Meijer Timmerman Thijssen, Dirk W. & Bressers, J.P.H.M. (2015). “Hoge Prevalentie van Vitamine D-deficiëntie in Zuidwest Nederland”. Nederlands Tijdschrift voor Geneeskunde 159:A8167. https://www.ntvg.nl/artikelen/hoge-prevalentie-van-vitamine-d-deficientie-zuidwest-nederland [Accessed on 13-04-2018].
