Vitamin D is commonly known as the “sunshine vitamin”. It has this nickname because when our skin is exposed to sunlight, our body is able to synthesize Vitamin D. Vitamin D is important for healthy bones and muscle, a good immune system, glucose metabolism, and cell growth. But in many populations around the world, vitamin D deficiency is common.
In this article, we will discuss the various things that can contribute to an increased risk of vitamin D deficiency, along with the common symptoms that occur in vitamin D deficiency, and ways to improve low vitamin D levels.
What populations have an increased risk of vitamin D deficiency?
- Breastfed infants: Human milk alone does not usually provide enough vitamin D to meet adequate intake levels. In addition, the American Academy of Pediatrics (AAP) advises parents to keep infants under 6 months old out of direct sunlight (1), so vitamin D through UV exposure does not usually occur in infants.
- Older adults: Vitamin D synthesis in the skin reduces with age and older adults are more likely to spend more time indoors (2).
- People with limited sun exposure: For example, those that wear head coverings for religious purposes or have occupations that limit sun exposure (3).
- People with darker skin: Increased skin melanin (which is what makes skin darker) reduces vitamin D synthesis because the increased melanin absorbs more of the sun rays before vitamin D synthesis is triggered (3).
- People who have conditions that limit fat absorption: For example, celiac disease and Crohn’s disease. These conditions reduce the absorption of vitamin D in the gut, as it is a fat-soluble vitamin.
- Obese people: Obesity is associated with an increased risk of deficiency, as the increased subcutaneous fat in obese individuals sequesters more of the vitamin D synthesized from sun exposure, so there is less available throughout the rest of the body (4).
- Stomach surgery: Unfortunately, the type of surgery that can be used to help with weight loss can also contribute to an increased risk of vitamin D deficiency, as it can affect the ability to absorb vitamin D and other vitamins and minerals from food (5).
- People with kidney disease: The kidneys convert vitamin D from supplements and the sun into an active form that can be used by the body. Chronic kidney disease inhibits this conversion (6).
- People taking certain medications: Some drugs can inhibit the body’s natural ability to convert vitamin D into its active form. These include antiepileptics, anti-inflammatories, antibiotics, some herbal remedies (e.g., St John’s wort), steroids, drugs used to treat some breast cancers, and cholesterol-lowering drugs (7).
What are the common symptoms of vitamin D deficiency?
Vitamin D deficiency can cause a range of symptoms (2), including:
- Bone pain
- Muscle weakness, aches, and cramping
- Mood changes, e.g., depression
Long-term vitamin D deficiency can lead to rickets in children and osteomalacia in adults, which are both characterized by soft and weak bones (2). Vitamin D deficiency also increases the risk of various other health complications, including diabetes, obesity, high blood pressure, cardiovascular disease, inflammatory diseases, asthma in children, and specific cancers (1).
How can I boost my vitamin D levels?
Many people who only have a mild vitamin D deficiency do not show any noticeable symptoms, and it is always better to diagnose and treat a health problem BEFORE it gets worse.
Checking your vitamin D levels is quick and simple. It just requires a simple finger prick blood sample with our Vitamin D Test. This test measures your blood concentration of 25-OH vitamin D, which is the main indicator of vitamin D status. This test can tell you if your levels are in the healthy optimal range, or if you have mild to moderate deficiency, or if you have a severe deficiency. It can also detect vitamin D levels that are too high (vitamin D toxicity), which can occur in people who take an excessive amount of vitamin D supplements.
Ways to increase your vitamin D levels include:
- Increase consumption of foods that naturally contain vitamin D, such as fish liver oils and fatty fish (e.g., cod liver oil, trout, and salmon)
- Ensure that you are choosing common foods that have been fortified with vitamin D (had vitamin D added to them). These include most dairy milk and plant milk options, and ready-to-eat breakfast cereals.
- Take dietary supplements that contain vitamin D, but be careful not to overdose on vitamin D.
1. Davis CD, & Dwyer JT. (2007). The ‘sunshine vitamin’: benefits beyond bone? J Natl Cancer Inst. 99, 1563-1565.
2. Dietary Reference Intakes for Calcium and Vitamin D. (2010). Washington, DC, USA: National Academy Press.
3. Vitamin D: Fact Sheet for Health Professionals (2020, October 9). NIH
4. Jones G. (2014). Vitamin D. In Ross AC, et al. Modern Nutrition in Health and Disease (11th ed). Philadelphia: Lippincott Williams & Wilkins.
5. Johnson JM, et al. (2006) The long-term effects of gastric bypass on vitamin D metabolism. Ann Surg. 243(5): 701-705.
6. Vitamin D: The Kidney Vitamin? National Kidney Foundation. August 2014.
7. Gröber U & Kisters K. (2012) Influence of drugs on vitamin D and calcium metabolism. Dermatoendocrinol. 4(2): 158-166.