All you need to know about Vitamin D (Vitamin D2 and D3)
Vitamin D, also known as calciferol, is an essential fat-soluble vitamin stored in our bodies until needed. It is obtained naturally from only a few foods and sun exposure; however, it can also be found in dietary supplements and fortified foods. Vitamin D plays a critical role in many bodily functions, including boosting our immune system, supporting our bone health, facilitating the absorption of calcium into our body, protecting us against certain types of cancers, and reducing the risk of illnesses like heart disease, amongst many other important benefits.
Types of Vitamin D
There are two major types of vitamin D: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). However, when people talk about vitamin D, they are inadvertently referring to Vitamin D3.
How is Vitamin D made?
Vitamin D is the only vitamin that can be made in the body. When the ultraviolet energy of the sun interacts with a certain type of cholesterol in our skin (7-dehyrocholesterol), vitamin D3 is formed. This is also why vitamin D is called the 'sunshine vitamin'.
Once formed in the skin, Vitamin D is inert and must undergo two steps to be fully activated – once in the liver and then a second time in the kidney. Vitamin D, as found in supplements and foods, is also inert and has to be activated similarly to vitamin D from the sun before use.
During the first activation step, Vitamin D is converted to 25-hydorxyvitamin D (calcitriol) in the liver. The second activation occurs in the kidney to form active Vitamin D, also known as calcitriol or 1,25-dihydrodymvitamin (calcitriol). This is the active form of vitamin D.
Exposure to the sun doesn’t provide adequate levels of vitamin D, making it important that we obtain vitamin D supplementation from our diet and vitamin D dietary supplements. Since only a small number of foods, like fish, shellfish, and vitamin D-fortified foods, contain significant vitamin D levels, deficiency in vitamin D is very common. Sadly, most people who are vitamin D deficient are unaware of it.
What happens if you don’t get enough Vitamin D?
It is estimated that at least 1 billion people are vitamin D deficient, with the incidences being worse in countries that experience decreased sunlight during the summer and winter months.
The most common symptom of vitamin D deficiency is rickets, a disease that causes irregular growth patterns and deformities in children. Other common symptoms of vitamin D deficiency include bone loss, bone pain, osteoporosis, increased risk of certain cancers, increased risk of certain heart problems, hair loss, fatigue/tiredness, general weakness, and impaired wound healing. Since vitamin D, when present, boosts our immune system, a deficiency in vitamin D can lead to an increase in certain types of illnesses.
How do you check Vitamin D levels?
Vitamin D levels can easily be measured by blood work ordered by your doctor. The two forms of vitamin D can technically be measured in the blood, though the blood test measures the most stable form, 25-hydroxyvitmain D. If the result shows vitamin D deficiency, your doctor will most likely order some supplements to boost your vitamin D level until it reaches acceptable blood ranges of 20–50 ng/ml.
What is the recommended Vitamin D supplement per day?
When our diet does not provide sufficient vitamin D, we often have to take supplements as recommended by a physician. A Vitamin D dose is measured in International Units (IU) and the recommended doses included:
Children up to 12 months – 400 International Units (IU)
Ages 1 to 70 years old – 600 IU
Ages 70 and above – 800 IU
Generally for adults, the recommended dose is 400–800 IU (10–20 micrograms) per day, although some experts think that’s too low, so you will also find a recommended daily dose (RDA) of 800–1000 IU per day as an option. To make things more confusing, you will find most dietary supplement labels suggest a dose of 1000–2000 IU (25–50 micrograms) per day. Regardless of what recommendation you follow, doses higher than 4,000 IU per day are not considered safe, do not offer any additional health benefits, and thus are not recommended. However, some studies show that doses up to 10,000 IU per day can been used without any noticeable side effects, but under the supervision of a physician, for special population, and on a case-by-case basis. Both Vitamin D2 and Vitamin D3 supplements are equally effective at boosting blood levels of Vitamin D, so you can take any of them.
Vitamin D2 is available as a prescription as well as an over-the-counter (OTC) supplement. Vitamin D3 is available only as an OTC. If you are vegan, be aware that some Vitamin D2 products may come from animal products, so be sure to look for vegan brands.
What are the Health benefits of Vitamin D?
Vitamin D has several health benefits, including (but not limited to):
Fighting flu and related viruses
Cancer prevention and reduction
Managing depression
Protecting the heart and reducing chances of heart disease
Reduction in incidence of type 1 diabetes
Increasing strength and stamina
Helping us control our weight
Reducing depression and improving mood
How to improve vitamin D levels in the body
Luckily, there are several sources of vitamin D as well as things we can do to improve our overall vitamin D levels, including:
Spending at least 30 mins in the sun daily
Eating eggs and butter
Eating fish at least twice a week
Drinking vitamin D fortified milk and orange juice
Taking fish oil supplements
Taking vitamin D supplements
What are the differences between vitamin D2 vs. vitamin D3?
Even though both types of vitamin D sound similar, there are many differences in how they are formed and where they are found.
Source of Vitamin D2 vs. Vitamin D3
Vitamin D2 comes from plant sources like mushrooms that are grown in UV light, dietary supplements, and also fortified food like milk, orange juice, cereal, and oatmeal. Vitamin D2 is cheaper to make than vitamin D3, so it is the more common version of vitamin D used in fortified foods.
Vitamin D3, on the other hand, is primarily made by our skin when exposed to sunlight. Unlike Vitamin D2 that comes from plants, Vitamin D3 comes from animal sources, including salmon, tuna, herring, sardines, butter, liver, egg yolks, as well as dietary supplements.
Effectiveness of Vitamin D2 vs. D3
Even though both vitamin D2 and vitamin D3 are important, studies have shown that vitamin D3, which is made from the reaction of the sun with our skin, is what sustains our blood vitamin D levels during the winter months when we don’t get enough sunlight. Our body generally absorbs vitamin D3 better, making it more effective in improving vitamin D levels in our body, almost twice as effective as vitamin D2.
At Vanda’s kitchen, we use ingredients rich in vitamin D when possible, such as that found in our salmon and vegan dishes. However, vitamin D is critical for general health and wellness, and since vitamin D deficiency is prevalent in the population, we advise that you not only make eating food rich in vitamin D part of your regular diet, but that you also talk to your physician about your vitamin D blood levels to make sure you are within a healthy range.