Vitamin D is an essential nutrient that plays a vital role in bone health. Extraordinary about the vitamin is that the body can produce it under specific circumstances. However, when the production is limited (for example, in the winter months), supplementing is often necessary to avoid vitamin D deficiency.
So in this post, you’ll learn everything you need to know about vitamin D, including sources, benefits, how to prevent deficiency, and what common deficiency symptoms are.
- Function and benefits of vitamin D
- Who is at risk for deficiency?
- How much vitamin D should you take?
- Are plant foods a source of vitamin D?
- Are animal products a source of vitamin D?
- How can you test if you get enough vitamin D?
- How severe is a vitamin D deficiency, and what are the symptoms?
- Is it dangerous to take in too much vitamin D?
- How to meet your vitamin D need
- Everything you need to know about vitamin D at a glance
Function and benefits of vitamin D
Vitamin D is vital for calcium balance and, together with vitamin K, ensures a healthy bone metabolism. It is also essential for phosphate metabolism as well as the immune system. Moreover, it is needed for signal transmission and has several regulatory functions.
An adequate intake of vitamin D can help prevent high blood pressure, coronary heart disease, Diabetes mellitus, some autoimmune diseases, and chronic inflammatory bowel disease.
Who is at risk for deficiency?
If you spend enough time out in the sun in the warmer months (April - October), the body produces all the vitamin D it needs. However, in the colder months or if you don’t get out a lot, the body’s production is limited, and the risk of deficiency rises.
Then those on plant-rich or vegan diets have an increased high risk of deficiency as plants only contain minute amounts of the vitamin.
However, omnivores and vegetarians often don’t get enough either. Regardless of diet, the elderly also have an increased risk because, with age, the body loses its ability to produce adequate amounts.
Regular blood tests are recommended to ensure you get enough of the vitamin.
How much vitamin D should you take?
When the body’s production is limited, and you need to supplement, the recommended daily intake is 20 µg/day. This recommendation holds true for pregnant women and nursing moms as well. The only exception are babies under the age of 12 months, who should receive 10 µg/day.
Are plant foods a source of vitamin D?
Some plants (avocado, mushrooms) contain small amounts of the vitamin, but most don’t contain any at all. To meet the required intake with those plant foods, you would have to eat unrealistically high amounts.
Enriched vegan products like almond milk, can help meet the requirement but usually don’t provide enough to meet the need.
Are animal products a source of vitamin D?
Animals (like humans) can produce vitamin D. Therefore, foods of animal origin like fish, dairy, and liver contain the vitamin.
How can you test if you get enough vitamin D?
It is necessary that you check your vitamin D levels with a blood test periodically to monitor for possible deficiencies. The best parameter to test for is 25-Cholecalciferol in the blood serum. Values* over 50 nmol/l show that you are meeting the required intake. *Reference values may vary depending on the laboratory
Another possibility is to measure the active vitamin D3 in the blood. However, because this parameter is relatively constant, even if there is a deficiency, it is not the most reliable option.
How severe is a vitamin D deficiency, and what are the symptoms?
A lack of vitamin D disrupts the calcium and phosphate metabolisms, which in turn increases the risk of bone fractures and osteoporosis. Moreover, it can lead to muscle diseases, increased risk of infection, as well as nerve and blood flow problems.
In children, vitamin D deficiency can lead to rachitis, which can cause problems with bone growth, may deform the spine, and delay dental development. Additionally, there is an increased risk of infections and bone fractures, as well as less muscle power.
Further, studies suggest a connection between certain diseases and vitamin D deficiency. These diseases are heart disease, autoimmune diseases, cancer (various forms), and Diabetes mellitus.
Deficiency symptoms can be:
- Frequent infections
- Bone, muscle and back pain
- Hair loss
- Slower wound healing
- Bone loss
Is it dangerous to take in too much vitamin D?
Regardless of how much time you spend out in the sun, the body is not going to produce more vitamin D than it needs.
It is also not possible to absorb too much vitamin D with food.
The only way to “overdose” on vitamin D is through supplements. Thus, it would be best if you never took more than the recommended amount listed on the supplement.
Consuming more than 100 µg/day can be harmful because it increases calcium uptake and also releases calcium from the bones. This leads to a lot of calcium floating around in the body, which can deposit in the arteries, heart, lungs, and kidneys, and promote atherosclerosis and kidney stones.
The first symptoms of a vitamin D “overdose” can be increased thirst, having to use the bathroom more often, feeling sick, throwing up, and reduced muscle tension.
How to meet your vitamin D need
As mentioned before, the body can produce vitamin D under specific circumstances. If those circumstances are not met, taking a supplement may be necessary.
Let's take a look at the requirements for vitamin D production in the body
- The sun has to be strong enough to facilitate vitamin D synthesis.
- In many parts of the world, this is only the case during the summer months (April – October).
- You need to spend enough time out in the sun.
- So, a few times every week for 10-30 minutes each.
- It is also important that 25% or more of your skin is uncovered.
- Moreover, wearing sunscreen during that time (even with a low SPF of 15) can hinder vitamin D production
Further, skin color, skin thickness, age, and air pollution also play a role.
What you need to know about supplementing
The most popular ones are drops, tablets, and capsules. How much and how often you need to take it depends on the supplement. Some you need to take every day, and others you only need to take once a week or once every couple of weeks.
Since too much vitamin D can be harmful, you should carefully follow the intake instructions on the packaging. Moreover, it a good idea to consult your doctor.
Also, look for a vegan label as there are supplements that contain vitamin D sourced from animal products.
To increase the absorption of vitamin D, it is helpful to take the supplement with fatty meals or by eating nuts before taking it.
Side note: Some vitamin D supplements come in combination with vitamin K. This is because excess vitamin D can lead to calcium deposits in the arteries, which can promote atherosclerosis. Vitamin K can help reduce those deposits. However, if you take your vitamin D as recommended, it is not necessary for the supplement to also contain vitamin K.
Again, I want to emphasize the importance of getting a blood test done regularly to monitor your vitamin D supply and to adjust your supplementing accordingly.
Everything you need to know about vitamin D at a glance
Are you taking a vitamin D supplement, or are you lucky enough to live in a place where it is warm all year? #jealous 😀