Key Points

  • Osteoporosis
  • Hyperparathyroidism
  • Depression/Anxiety
  • SAD
  • Weight gain 
  • Increased Risk of autoimmune disease

Vitamin D Deficiency


Vitamin D has several health benefits, firstly it helps increase bone health by allowing an increase of calcium absorption (1), secondly it can regulate immune function (2) and modulate inflammatory response (3). Vitamin D has also been found to be key to optimal muscle function (4). The importance of Vitamin D in athletes whether professional or amateur has been noted as being vital for performance (5).



Being deficient in Vitamin D can result in a host of complications including an increased chance of seasonal affective disorder or ‘the winter blues’ as it is also known as can lead to depression and lack of interest in day to day life, irritability and sluggish or easily agitated (6). 

As well as this another condition could arise which is hyperparathyroidism which is due to one or more of your parathyroid glands making too much parathyroid hormone that can lead to an increase of calcium in the blood which could result in kidney stones (7). 

The link between weight gain and lack of vitamin D is one that is contested, however the essential premise is that vitamin D is stored within fat tissue and so someone who has a lot of fat tissue may require a larger dose (8). It is also possible that there is an increased risk of autoimmune diseases such as rheumatoid arthritis (9).

It is recommended to consume 10 micrograms of Vitamin D daily.


1 – Holick, M. F. (2007). Vitamin D deficiency. New England Journal of Medicine,357(3), 266-281.

2 – Gombart, A. F., Borregaard, N., & Koeffler, H. P. (2005). Human cathelicidin antimicrobial peptide (CAMP) gene is a direct target of the vitamin D receptor and is strongly up-regulated in myeloid cells by 1, 25-dihydroxyvitamin D3. The FASEB Journal, 19(9), 1067-1077.

3 – Zittermann, A. (2003). Vitamin D in preventive medicine: are we ignoring the evidence?. British Journal of Nutrition, 89(05), 552-572.

4 – Hamilton, B. (2010). Vitamin D and human skeletal muscle. Scandinavian journal of medicine & science in sports, 20(2), 182-190.

5 – Larson-Meyer, D. E., & Willis, K. S. (2010). Vitamin D and athletes. Current sports medicine reports, 9(4), 220-226.

6 – Fonte, A., & Coutinho, B. (2021). Seasonal sensitivity and psychiatric morbidity: study about seasonal affective disorder. BMC psychiatry, 21(1), 1-7.

7 – Bilezikian, J. P., Bandeira, L., Khan, A., & Cusano, N. E. (2018). Hyperparathyroidism. The Lancet, 391(10116), 168-178.

8 – Vranić, L., Mikolašević, I., & Milić, S. (2019). Vitamin D deficiency: consequence or cause of obesity?. Medicina, 55(9), 541.

9 – Kostoglou-Athanassiou, I., Athanassiou, P., Lyraki, A., Raftakis, I., & Antoniadis, C. (2012). Vitamin D and rheumatoid arthritis. Therapeutic advances in endocrinology and metabolism, 3(6), 181-187.