VITAMIN D & HEALTH

Vitamin D and Calcium Absorption

Vitamin D and calcium are two essential nutrients that work together to support overall health and well-being, especially in our bones. Calcium is essential for maintaining strong bones and teeth. On the other hand, vitamin D plays a crucial role in helping the body absorb and use calcium effectively.¹ Let us delve deep and explore the relationship between vitamin D and calcium absorption, unlocking the answers as to why it is so important for our health.

How Does Calcium Absorption Work?

Before discussing the relationship between calcium and vitamin D, we first have to understand the mechanics of calcium. Calcium is a mineral that is essential for bone health, muscle function, nerve transmission, and other important physiological processes in the body.² While calcium is found in many different foods, including dairy products, leafy greens, and fortified cereals, the body cannot absorb and use calcium effectively without vitamin D.¹

When calcium is ingested, it travels through the digestive system and into the small intestine. There, it is absorbed into the bloodstream and transported to the bones and other tissues where it is needed. However, calcium can only be absorbed into the bloodstream when it is in an ionised form. This is where the role of vitamin D comes in.³

How Does Vitamin D Support Calcium Absorption?

Vitamin D plays a key role in helping the body absorb and use calcium effectively. When vitamin D is ingested or synthesised by the body through sunlight exposure, it is converted into its active form, which is known as calcitriol.⁴ Calcitriol helps to regulate the absorption of calcium in the small intestine, by increasing the production of calcium-binding proteins that help to transport calcium from the intestine into the bloodstream.⁵

In addition to supporting calcium absorption, vitamin D also helps to regulate calcium levels in the blood. If calcium levels in the blood are too low, the body will produce more calcitriol to increase calcium absorption and uptake from the bones. On the other hand, if calcium levels in the blood are too high, the body will produce less calcitriol to decrease calcium absorption and increase excretion.⁶

Why is the Relationship Between Vitamin D and Calcium Absorption Important?

The relationship between vitamin D and calcium absorption is crucial for maintaining strong bones and overall health. Without vitamin D, the body would not be able to absorb and use calcium effectively, which can lead to a host of health problems.

Inadequate calcium intake and absorption can lead to weakened bones and an increased risk of fractures and osteoporosis, especially in older adults. In addition, calcium deficiency can cause muscle cramps, spasms, weakness, and other symptoms such as fatigue and irritability.⁷

Low levels of vitamin D can also lead to a range of health problems beyond bone health, including an increased risk of certain types of cancer, autoimmune diseases, and infectious diseases.⁸Vitamin D deficiency has also been linked to depression, cognitive impairment, and other mental health issues.^9,10

How Can You Ensure You are Getting Enough Vitamin D and Calcium?

To ensure you are getting enough vitamin D and calcium, it is important to maintain a healthy, balanced diet that includes a variety of foods rich in these nutrients. Some of the best food sources of calcium include dairy products such as milk, cheese, and yoghurt, as well as leafy greens like spinach and kale, and fortified cereals and juices.¹

To get enough vitamin D, it is important to get regular sunlight exposure and eat foods that are high in vitamin D, such as fatty fish like salmon, egg yolks, and fortified dairy products. However, for some people, especially those with limited sun exposure or certain medical conditions, it may be difficult to get enough vitamin D from food sources alone.¹¹

In these cases, vitamin D supplements may be recommended to help ensure adequate vitamin D intake. It is important to talk to a healthcare provider before taking vitamin D supplements to accurately determine the dosage needed based on many factors ranging from existing health issues, lifestyle, age, and even skin colour.¹²

In conclusion, our bodies require calcium to maintain healthy bones and teeth. Even if our calcium intake is sufficient, without vitamin D, our bodies will not be able to absorb calcium effectively. This will lead to a multitude of issues pertaining to a deficiency in calcium and vitamin D. To read more about these issues, refer to our section on Vitamin D deficiency.

References
1) The President and Fellows of Harvard College. “Calcium | The Nutrition Source | Harvard T.H. Chan School of Public Health.” Harvard T.H. Chan School of Public Health. Available at:
https://www.hsph.harvard.edu/nutritionsource/calcium/. Accessed 16 February 2023.
2) National Academy of Sciences. “Overview of Calcium – Dietary Reference Intakes for Calcium and Vitamin D.” NCBI. Available at:
https://www.ncbi.nlm.nih.gov/books/NBK56060/. Accessed 16 February 2023.
3) Medical University of South Carolina. “Calcium Supplements & Absorption.” MUSC Health. Available at:
https://muschealth.org/medical-services/geriatrics-and-aging/healthy-aging/calcium. Accessed 16 February 2023.
4) Meurer, Michael. “Extrarenal sites of calcitriol synthesis: the particular role of the skin.” PubMed. Available at:
https://pubmed.ncbi.nlm.nih.gov/12899518/. Accessed 16 February 2023.
5) Lung, Brandon E., et al. “Calcitriol – StatPearls.” NCBI, 19 July 2022. Available at:
https://www.ncbi.nlm.nih.gov/books/NBK526025/. Accessed 16 February 2023.
6) Society for Endocrinology. “Vitamin D.” You and Your Hormones. Available at:
https://www.yourhormones.info/hormones/vitamin-d/. Accessed 16 February 2023.
7) Biggers, Alana. “Calcium deficiency disease (hypocalcemia): 7 symptoms and causes.” Medical News Today. Available at:
https://www.medicalnewstoday.com/articles/321865. Accessed 16 February 2023.
8) Marengo, Katherine, and Jerlyn Jones. “Vitamin D Deficiency: Symptoms, Treatments, and Causes.” Healthline. Available at:
https://www.healthline.com/nutrition/vitamin-d-deficiency-symptoms. Accessed 16 February 2023.
9) Brennan, Dan. “Does Vitamin D Boost Mental Health?” WebMD, 30 March 2021.
Available at:
https://www.webmd.com/vitamins-and-supplements/what-to-know-about-vitamin-d-and-mental-health. Accessed 16 February 2023.
10) Shea, Kyla M. “Brain vitamin D forms, cognitive decline, and neuropathology in community-dwelling older adults.” Alzheimer’s Association, 7 December 2022. Available at:
https://alz-journals.onlinelibrary.wiley.com/doi/full/10.1002/alz.12836. Accessed 16 February 2023.
11) The President and Fellows of Harvard College. “Vitamin D | The Nutrition Source | Harvard T.H. Chan School of Public Health.” Harvard T.H. Chan School of Public Health. Available at:
https://www.hsph.harvard.edu/nutritionsource/vitamin-d/. Accessed 16 February 2023.
12) Cleveland Clinic. Vitamin D Deficiency: Causes, Symptoms & Treatment. Cleveland Clinic. 8 February 2022. Available at:
https://my.clevelandclinic.org/health/diseases/15050-vitamin-d-vitamin-d-deficiency/. Accessed 6 March 2023.