You may have noticed that vitamin D and calcium are often spotted hanging out together on the shelves of the vitamin aisle. While they may seem like unlikely bedfellows, these two nutrients create a powerhouse when combined, resulting in a number of benefits for the body. 

What are vitamin D and calcium good for?

Before we get down to how vitamin D and calcium work together, let’s look at the two separate sides of this love story. 

Vitamin D^[1]

Known as the ‘sunshine vitamin’, vitamin D is both a nutrient we eat and a hormone our bodies make. This fat-soluble vitamin comes in two forms: D2 (‘ergocalciferol’ or pre-vitamin D) and D3 (cholecalciferol – this is the baby your body loves). There are only a few foods that naturally contain vitamin D3, so the body’s primary source is via sunlight, which causes it to be produced in the skin. 

Vitamin D helps the body absorb and retain calcium, which is critical for building bone, and it’s also important for immune health and muscle function support1. However, due to insufficient exposure to sunlight, it’s estimated that around a quarter of Australians are vitamin D deficient^[2].

Calcium^[3]

Calcium is important for healthy bones and teeth, and also for helping muscles to contract. About 99% of the body’s calcium is stored in the bones and the remaining 1% is found in blood, muscle, and other tissues^[3]. 

The body needs to keep a steady amount of calcium in the blood and tissues. If calcium levels in the blood drop too low, the body will “borrow” calcium from bones, with the intention of replacing it at a later date. The body will also eliminate calcium through the kidneys to maintain stability and self-regulation, so it’s important to keep replenishing supplies of it^[4].

Why should you take vitamin D and calcium together?^[5]

When vitamin D and calcium come together, the focus is all on your bones. As mentioned, calcium is necessary for strong, healthy bones – it can increase bone density and reduce bone loss (when the body takes calcium from the bones and isn’t able to replace it, leading to them becoming weak and brittle). This is particularly important for older people, when osteoporosis is a real risk. Vitamin D helps the body to better absorb calcium and also supports bone health in other ways. 

Which foods have vitamin D and calcium?

Vitamin D is present in a small amount of foods like fatty fish (such as salmon, tuna and swordfish), fish liver oils, beef liver, egg yolks and cheese^[1], but the best way to top up your intake is through adequate amounts of sun exposure, while being mindful of sun safety. 

The best-known calcium sources are milk and dairy products, and it’s also present in fruit, leafy greens, beans, nuts, and some starchy vegetables^[2].

Both vitamin D and calcium are available in supplement format – often in a combined supplement - which is an easy and efficient way of increasing your intake. 

When should I take calcium and vitamin D?

Don’t make the mistake of thinking that bone health is something you can worry about “later”. Start taking care of your bones and teeth now by ensuring your body has enough vitamin D and calcium. Consult with your healthcare professional on how much you need to take daily, as this differs depending on sex and life stage. If you want to give your bones some extra support, try incorporating weight-bearing physical activities into your daily routine, such as running or dancing, as they are great for bone health. 

References:
[1] Vitamin D. Harvard School of Public Health. https://www.hsph.harvard.edu/nutritionsource/vitamin-d/  Article sourced: 14 March 2023
[2] Australian Bureau of Statistics 2011, Australian Health Survey: Biomedical Results for Nutrients, ABS. https://www.abs.gov.au/statistics/health/health-conditions-and-risks/australian-health-survey-biomedical-results-nutrients/2011-12 Article sourced 14 March 2023
[3] Calcium. Harvard School of Public Health. https://www.hsph.harvard.edu/nutritionsource/calcium/ Article sourced: 14 March 2023
[4] Natalia Wawrzyniak, Joanna Suliburska, Nutritional and health factors affecting the bioavailability of calcium: a narrative review, Nutrition Reviews, Volume 79, Issue 12, December 2021, Pages 1307–1320, https://doi.org/10.1093/nutrit/nuaa138 
[5] Patient education: Calcium and vitamin D for bone health (Beyond the Basics). UpToDate. https://www.uptodate.com/contents/calcium-and-vitamin-d-for-bone-health-beyond-the-basics Article sourced: 14 March 2023