Vitamin D: The new insights

Vitamin D is one of the most commonly supplemented vitamins. A tremendous amount has already been written and researched about its effects at different dosages and the importance of the various forms of vitamin D. To this day, numerous studies are still underway, continuously generating new knowledge and potential applications.

All forms of vitamin D

Vitamin D is usually associated solely with vitamin D3, but it actually occurs in several forms (vitamers). D3 is the main form and is produced by the body. But are you familiar with the other forms? Here they are at a glance:

• Vitamin D1: formed from a 1:1 combination of ergocalciferol (vitamin D2) and lumisterol.
• Vitamin D2: ergocalciferol. This vitamer is produced only in fungi or yeasts and is added to margarine and breakfast cereals in some countries.
• Vitamin D3: cholecalciferol. It is produced when bare skin is exposed to UV-B light and plays a role in the formation and maintenance of bones and the absorption of calcium.
• Vitamin D4: 22-dihydroergocalciferol. This vitamer occurs naturally only in mushrooms.
• Vitamin D5: sitocalciferol. This synthetically created vitamer is also used in treatments for prostate cancer because, unlike D3, it does not cause hypercalcaemia at higher doses.

With so much information available about vitamin D3, some confusion is inevitable. For example, D3 is often referred to as the “sunshine vitamin”, although this is not entirely accurate. This is because the vitamin D3 produced by our skin under the influence of sunlight is not the same form as the one found in nutritional supplements and therefore does not have exactly the same properties. You can find more about this and other interesting information about vitamin D3 supplements here.

What you may not know about vitamin D3

As mentioned, recent scientific research into vitamin D3 continues to produce a steady stream of new information. Previous assumptions are sometimes challenged, while new discoveries are made about the absorption of vitamin D3 and which nutrients and behaviours may promote or inhibit this process. The influence of human behaviour on nutrient absorption should not be underestimated, as it can play a significant role in determining how much of the vitamin D3 you consume can actually be used effectively by your body. For example, were you aware of the following facts about vitamin D3 absorption?

• Excessive alcohol consumption inhibits the absorption of vitamin D3 in the small intestine and its processing in the liver. Long-term alcohol consumption can damage the delicate intestinal lining of the small intestine, making it less effective at allowing nutrients to pass through. After absorption, vitamin D3 is metabolised in the liver into biologically available components. With excessive alcohol consumption, the liver, which is also responsible for breaking down alcohol, is placed under considerable strain and can suffer irreversible long-term damage, reducing its ability to function properly.
• Determining whether you have sufficient vitamin D3 in your blood can be difficult without a blood test. One method sometimes used to estimate this yourself is the compression test: using your thumb, apply light pressure to the centre of your breastbone or your shins. Does it hurt? This may indicate a possible vitamin D3 deficiency. You can read more about the compression test here.
• If a blood test shows that your vitamin D3 status is low, you could consider this an indication of your need for essential sunlight – are you getting enough sun exposure without sun protection? Interestingly, vitamin D3 produced through sunlight cannot cause an overdose! Unprotected sun exposure may seem controversial according to current consensus, but sunlight on bare skin has numerous important properties. We explore this in greater detail in a blog about the advantages and disadvantages of sunlight.
• Not only humans but also edible mushrooms produce vitamin D when exposed to UV light. While this generates D3 in humans, mushrooms mainly produce D2 and, to a lesser extent, D3 and D4. By eating fresh mushrooms, you can contribute to your daily vitamin D intake in a natural, plant-based way – this vitamin is otherwise found predominantly in animal sources.
• In addition to the possibility that caffeine can interfere with optimal calcium metabolism, a similar effect has also been observed in the metabolism of vitamin D3. During a scientific study involving a daily caffeine intake of 300 mg or more – with the effect becoming stronger as the caffeine dose increased – D3 receptors in osteoblasts (cells responsible for bone mineralisation and formation) absorbed less vitamin D3, resulting in less D3 being metabolised. Consistently consuming large quantities of caffeinated beverages may therefore have negative consequences for bone density over the long term.
• According to preliminary results from recent research, resveratrol (available as a nutritional supplement and also found in red wine) may be able to improve vitamin D3 absorption by potentially activating D3 receptors in the body and encouraging them to bind with vitamin D3. Drinking red wine is healthy – in moderation!

Vitamin D and the immune system

Vitamin D's involvement in the normal functioning of the immune system is well known, and scientific research has repeatedly demonstrated this property. At the same time, a large proportion of the population may require more vitamin D than they are able to obtain through food alone. This is particularly relevant during the darker months, when less D3 can be produced through exposure to sunlight, and for people who spend less time outdoors or who could benefit from a healthier diet. It is therefore no coincidence that vitamin D has recently been mentioned again by various news sources as the days become shorter and spending more time indoors becomes increasingly relevant.

In the United Kingdom, the prime minister even decided to respond to this in a remarkable way: In Scotland, the NHS (the UK's public healthcare system) had already decided to provide all Scottish residents for whom additional vitamin D intake was considered particularly important with a four-month supply of vitamin D supplements. A similar measure was also being considered in England.

What do you think? Should all governments provide their populations with free vitamin D supplements to support their immune defences, or would better education about responsible sun exposure and nutrition be a better approach?

Our favourite Vitamin D products

The one and only Extra Virgin Cod Liver Oil

• Traditional & patented process
• Source of omega-3 fatty acids
• Rich in vitamins A and D
• 500 mg per softgel
• 90 softgels

Vitamin D3 1000 IU - 180 softgels - Doctor's Best

Vitamin D3 - 5000 IU - 60 capsules - Momentous