What helps vitamin D absorption?

Vitamin D deficiency has become a much more popular subject in recent years, particularly during the darker winter months. Many people now take vitamin D supplements as a means of boosting their health – but what many don’t realise is that how you consume vitamin D is just as important as how much.

Like other essential nutrients, vitamin D plays a critical role in our bodies, but it can only do this if it’s absorbed and used effectively. Without the right conditions, it’s possible that a vitamin D supplement, no matter how high-quality it is, may not provide the benefits you’re hoping for. 

Below, we explore how vitamin D absorption works so you can make a real difference to your health.

How do we absorb vitamin D?

Vitamin D is a fat-soluble vitamin, which means it behaves differently in the body compared to water-soluble vitamins like vitamin C. Instead of being absorbed directly into the bloodstream, vitamin D needs dietary fat to help it pass through the gut and enter circulation.¹

Because of this, it’s recommended that you take vitamin D with a meal that includes healthy fats, such as olive oil, nuts, seeds, avocados or oily fish. If you currently take vitamin D on an empty stomach, you could be missing out on some of the vitamin’s benefits.

Once absorbed, vitamin D doesn’t become active straight away. It first travels to the liver and then to the kidneys, where it’s converted into its active form – in other words, a form that the body can actually use.² 

This process relies on several nutrients, with magnesium playing a particularly important role by supporting the enzymes involved.³ Without enough magnesium, vitamin D might not be converted efficiently – meaning you could lose out even if you’re getting enough vitamin D.

That’s why maintaining healthy magnesium levels – through a balanced diet or supplements such as a magnesium complex – is a great way to support vitamin D in the body.

What is the difference between vitamin D2 and vitamin D3?

When choosing a supplement, you might notice that vitamin D comes in two main forms: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). While both help raise vitamin D levels in the body, there are some important differences.

Vitamin D2 is derived from plant sources, often produced by exposing yeast or fungi to ultraviolet light.⁴ Because of this, it is entirely plant-based, making it suitable for vegans and vegetarians. 

Vitamin D3, on the other hand, is the same form of vitamin D that the body produces naturally when skin is exposed to sunlight.⁵ It’s usually derived from animal sources such as lanolin from sheep’s wool, and is the kind you’ll get from egg yolks, red meats, oily fish or liver. 

Research suggests that vitamin D3 may be absorbed more efficiently and remain active in the body for longer compared to D2.⁶ For this reason, D3 is typically the version recommended in supplements.

However, this doesn’t mean D2 is ineffective. Both forms raise vitamin D levels, and the best choice often depends on your dietary preferences, lifestyle and personal needs. For those who can take D3, a supplement such as vitamin D3 + K2 tablets may offer improved absorption and longer-lasting effects.

 

How to take vitamin D correctly

Taking vitamin D “correctly” doesn’t need to be complicated. Small changes to your routine can help your body to absorb and use it more effectively.

Take vitamin D with food
Because vitamin D is fat-soluble, always try to take it with a meal that contains healthy fats. Breakfast or lunch is often ideal, especially if you include foods like eggs, avocado, olive oil or fortified yoghurt.

Support magnesium intake
As mentioned earlier, magnesium helps your body to convert vitamin D into its active form.³ Including magnesium-rich foods such as leafy greens, whole grains, nuts and seeds can be beneficial. 

Choose the right form where possible
If you’re not vegan, vitamin D3 is the best choice due to its higher absorption rate. If you are vegan, vitamin D2 remains a reliable and suitable option.

Be consistent
Results don’t happen overnight. Taking your supplement regularly, rather than occasionally, helps to maintain steady levels of vitamin D over time.

Consider supportive nutrients
Vitamin D works alongside other minerals in the body. For bone health in particular, nutrients such as vitamin K, calcium and phosphate help to support proper mineral balance and bone strength. Some supplements combine these nutrients for convenience.

Example meal idea
Theory is all well and good, but how can you actually put this information to good use? 

A simple meal idea could be grilled salmon (or tofu for vegans), roasted vegetables drizzled with olive oil, and a side of leafy greens. This provides healthy fats, magnesium and a supportive environment for vitamin D absorption.

What if I’m vegan?

If you follow a vegan diet, vitamin D2 is the most appropriate choice, as it’s entirely plant-based⁴. You can still follow most of the same advice to improve absorption.

Of course, you’ll want to avoid animal-based sources of key nutrients, so plant-based sources will be vital. These include:

• Healthy fats: nuts, seeds, avocado and olive oil
• Magnesium: spinach, pumpkin seeds, almonds, beans and whole grains
• Vitamin D: some vitamin-enriched mushrooms, plus many fortified foods such as plant milk and cereals.

Supporting healthy levels of vitamin D isn’t as difficult as it might seem. Making a few simple changes to your daily routine, such as taking your supplement with healthy fats, being consistent and getting enough of other key nutrients can make a big difference in the long term.

By understanding how vitamin D is processed and used in the body, you can consume it in the most efficient way to support your bones and overall health and wellbeing, both now and in the future.

References

1. National Institutes of Health. (2023). Vitamin D – Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
2. Holick, M. F. (2007). Vitamin D deficiency. New England Journal of Medicine, 357(3), 266–281. https://www.nejm.org/doi/full/10.1056/NEJMra070553
3. Harvard T.H. Chan School of Public Health. (n.d.). Vitamin D. https://www.hsph.harvard.edu/nutritionsource/vitamin-d/
4. European Food Safety Authority. (2016). Vitamin D2 and D3 as sources of vitamin D. https://www.efsa.europa.eu/en/efsajournal/pub/4547
5. NHS. (2023). Vitamin D. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/