How to enhance the absorption of vitamin D

Did you know that there is a debate about whether vitamin D should continue to be considered as a vitamin? Vitamins are substances that are generally not synthesised in the body, and dietary or supplementary intake is required. Interestingly, vitamin D can be made in the skin from a pro-vitamin under the influence of ultraviolet light.  

Although we can use the sun to make our own vitamin D, there are still circumstances in which we might not be able to get enough sun exposure or to be able to synthesize enough vitamin D in our body. For instance, in countries where the summer is shorter than the winter, people would have less months in which they can enjoy the sun and produce enough vitamin D. In the United Kingdom, people could get enough UV light only between April and September. This is why the government advises that everyone within the UK should consider taking a daily supplement containing 10ug (micrograms) of vitamin D.

How to enhance the absorption of vitamin D

Let's start with the fact that vitamin D is a fat-soluble vitamin. Fat-soluble vitamins are absorbed in the intestines in the presence of fat. The concurrent presence of fat in the gut enhances the absorption of fat-soluble vitamins, including Vitamin D.

What would this mean?

This would mean that if we are having our vitamin D with a fat-containing meal, we can enhance the absorption rate of the vitamin. A study done in 2010 reported that taking vitamin D with the largest meal improves absorption and results in about a 50% increase in serum levels of 25(OH)D levels. Moreover, the presence of fat in a meal with which a vitamin D supplement is taken can significantly enhance the absorption of the supplements.

Although it is still not clear how much fat we need to get the maximum absorption of vitamin D, it is evident that if we consume fats in our meals and snacks throughout the day we will increase the vitamin D's absorption rate. Thus leading to the desired increase in vitamin D blood levels.

Which foods contain fat?

Some foods that are rich in fats are:

• fatty fish such as salmon and sardines
• avocado
• eggs
• milk and milk products
• Greek yoghurt
• kyr
• cheese
• ghee
• olives and olive oil
• nuts and seeds (walnuts, cashews, sunflower seeds, pumpkin seeds)
• coconut

Which foods contain vitamin D?

• Oily fish such as salmon, sardines, pilchards, trout, herring, and kippers.
• Cod liver (not recommended during pregnancy, as it's really high in vitamin D).
• Egg yolk, offal, meat, milk (contain small amounts and the quantity of vitamin D in these foods may vary during different seasons).
• Some breakfast cereals, infant formula milk and some yoghurts may have added vitamin D.
• Mushrooms.
• Plant milk alternatives such as soy milk, oat milk and almond milk are often fortified with vitamin D.

These are just a few examples of how you can enhance the absorption of vitamin D in your diet, but if you'd like to find out more, you may find it helpful to work with a nutritional professional, such as a registered dietitian. 

References

• Mulligan, G.B., and LICATA, A.,  2010. Taking vitamin D with the largest meal improves absorption and results in higher serum levels of 25-hydroxyvitamin D. Journal of Bone Miner Res, 25(4), pp. 928-930.
• Dawson-Hughes, B. et al. 2014. Dietary fat increases vitamin D-3 absorption. Journal of Acad Nutr Diet, 115(2), pp. 225-230.
• NHS, 2023. Vitamins and Minerals: Vitamin D. [online]. UK: National Health Services. Available from: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/ (Accessed 10th October 2023).
• British Diabetic Association, 2023. Vitamin D. [online]. UK: British Dietetic Association. Available from: https://www.bda.uk.com/resource/vitamin-d.html (Accessed 10th October 2023).
• National Institutes of Health (NIH), 2023. Vitamin D. Fact Sheet for Health Professionals. [online]. USA: NIH. Available from:https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/ (Accessed 10th October 2023).