A closer look at Vitamin D

Vitamin D is often referred to as the sunshine vitamin because it is produced when skin is exposed to the sun. Vitamin D has two main forms in humans, vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol), both being fat soluble. [1] There are two main dietary forms, Vitamin D3 found in some animal foods, like fatty fish and egg yolks and Vitamin D2 found in some plants, mushrooms, and yeasts. Of the two, D3 seems to be almost twice as effective at increasing blood levels of vitamin D as D2. [2]

Vitamin D promotes calcium absorption in the gut and maintains adequate calcium and phosphate concentrations.  This is important for bones and muscles. You may have heard of the disease rickets in children where lack of vitamin D creates bone weakness and deformities. Vitamin D also has other roles in the body including the reduction of inflammation and involvement in cell growth, neuromuscular and immune functions and glucose metabolism.[2]

There are a lot of areas where Vit D is beneficial to our health; we are going to take a closer look at its role in energy levels, mood and fertility.

Could vitamin D give you more energy?

Vitamin D impacts on calcium which links to phosphate and phosphate is one of the key components of the body’s battery, adenosine triphosphate (ATP). From this interlinking chain it would seem logical that vitamin D might affect energy levels. As is often the case there does need to be further research. There was a double blind randomised placebo-controlled trial (in theory the best type!) in 2016 that concluded that vitamin D treatment significantly improved fatigue in otherwise healthy persons with vitamin D deficiency. [5] In 2014 the so called EViDiF Study found normalisation of vitamin D levels with ergocalciferol therapy significantly improved the severity of fatigue symptoms [6] and in the same year a study on Exercise Performance in Professional Soccer Players showed  reductions in exercise training stress associated with vitamin D levels. [7]

A sunshine mood

Somewhat logically, as vitamin D levels are linked to exposure to the sun, the impact of its deficiency in relation to mental health have been picked up in northern latitudes. Lots of us notice in ourselves or those around us a change in mood in the winter months, in fact there is a whole medical phenomenon around it, Seasonal Affective Disorder (SAD). A study in Iceland found that men with deficient vitamin D status were more likely to have current major depressive disorder compared with men with adequate vitamin D status although interestingly associations among women were not significant. [8] Again from 2014 (big year for vitamin D studies it seems!) a review of vitamin D supplementation for depressive symptoms found supplementation may be effective for reducing symptoms in patients with clinically significant depression. [9] Another recommendation, in the same year, was that serum vitamin D levels should be measured in patients with schizophrenia especially in long term care as it was found there was a severe vitamin D deficiency in patients presenting with an acute episode. [10]

Vitamin D and fertility

In men recognising the fact that sperm quality is decreasing and infertility is a problem affecting about 10–15% of couples, vitamin D status might be related to spermatogenesis, semen quality, and testiculopathies as well as male hypogonadism. [11] There are a number of studies linking vitamin D deficiency with poorer semen quality. [12, 13, 14]

 For women the picture is less clear. A 2012 study published in Journal of Clinical Endocrinology and Metabolism reveals that pre-menopausal women’s Anti-Müllerian Hormone (AMH) level changes in correlation to the seasonal changes of vitamin D levels within the body. [15] Having a high amount of AMH indicates you have plenty of egg-containing follicles – which is useful if you want to become pregnant. Also a high AMH level is particularly useful when you’re doing IVF. Therefore lower vitamin D could suggest less successful implantation and pregnancy. Whilst the normal range of Vitamin D is between 20 and 50ng/ml, for women trying to conceive, about 35ng/ml is ideal.

A thorough review of vitamin D and fertility states there is evidence that vitamin D exerts some effects on female reproduction including In Vitro Fertilisation (IVF) outcome, Poly Cystic Ovary Syndrome (PCOS), and endometriosis as well as on steroidogenesis in healthy women. [11] A study on women undergoing single embryo, blastocyst stage, transfer (SET) for IVF/intracytoplasmic sperm injection (ICSI) found clinical pregnancy rates in women with vitamin D deficiency were significantly lower. [16] However there are a number of studies where vitamin D levels did not bear any relation to the success of assisted reproduction. [17, 18, 19] One did state the higher vitamin D levels did translate into higher fertilisation rates, but this apparent benefit does not translate into higher probability of pregnancy or live birth. Finally an article asking if vitamin D is the Trojan Horse or Golden Fleece of reproductive health summarises - vitamin D is definitely not a Trojan Horse in reproductive health, since there were no adverse effects reported for vitamin D intake of up to 10,000 IU/day, but to proclaim it the Golden Fleece, more evidence is needed. [20]

In many ways this is a good conclusion, especially as vitamin D is easy to supplement and vitamin D toxicity is rare. Vitamin D is also now available as an oral spray; this is not only easier than swallowing tablets it also allows two routes for the vitamin to get into your blood stream. It can be absorbed into the body through your mucous membranes of your mouth as well as any excess being absorbed through the wall of the gut. Plus it comes in nice flavours to encourage you to want to take your dose.

References

1.       https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/

2.       Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. Tripkovic L. et al. Am J Clin Nutr 2012;95:1357–64

3.       Prevalence of Vitamin D Deficiency and Associated Risk Factors in the US Population (2011-2012). Parva N et al. Cureus 10(6): e2741 DOI: 10.7759/cureus.2741

4.      https://www.healthline.com/nutrition/vitamin-d2-vs-d3

5.       Effect of vitamin D3 on self-perceived fatigue: A double-blind randomized placebo-controlled trial. Nowak A. et al. Medicine (Baltimore) 2016 Dec; 95(52):e5353 DOI: 10.1097/MD.0000000000005353

6.        Correction of Low Vitamin D Improves Fatigue: Effect of Correction of Low Vitamin D in Fatigue Study (EViDiF Study). Roy S. Et al. North American Journal of Medical Sciences August 2014 Volume 6, Issue 8

7.       Vitamin D and Exercise Performance in Professional Soccer Players. Koundourakis N.E. et al. PLoS ONE, 1 July 2014 Volume 9 Issue 7

8.       Depression and serum 25-hydroxyvitamin D in older adults living at northern latitudes - AGES-Reykjavik Study. Imai CM et al. J Nutr Sci. 2015 Nov 20;4:e37. doi: 10.1017/jns.2015.27

9.       Vitamin D Supplementation for Depressive Symptoms: A Systematic Review and Meta-analysis of Randomized Controlled Trials, Shaffer J.A. et al. Psychosom Med. 2014 April ; 76(3): 190–196. doi:10.1097/PSY.0000000000000044

10.   Correlation between total vitamin D levels and psychotic psychopathology in patients with schizophrenia: therapeutic implications for add-on vitamin D augmentation. Yüksel R.N. et al. Ther Adv Psychopharmacol 2014, Vol. 4(6) 268–275 DOI: 10.1177/ 2045125314553612

11.   Vitamin D and fertility: a systematic review. Elisabeth Lerchbaum and Barbara Obermayer-Pietsch. European Journal of Endocrinology (2012) 166 765–778

12.   Vitamin D deficiency and low ionized calcium are linked with semen quality and sex steroid levels in infertile men. Blomberg Jensen M. et al. Human Reproduction, Vol.31, No.8 pp. 1875–1885, 2016. doi:10.1093/humrep/dew152

13.   Vitamin D in human reproduction: a narrative review. Anagnostis P. Et al.  Int J Clin Pract 2013 Mar;67 (3):225-35. doi: 10.1111/ijcp.12031

14.   Possible influence of vitamin D on male reproduction. Boisen I.M. The Journal of Steroid Biochemistry and Molecular Biology Volume 173, October 2017, Pages 215-222

15.   A Validated Model of Serum Anti-Mu¨llerian Hormone from Conception to Menopause. Kelsey T.W. et al. PLoS ONE July 2011 Volume 6 Issue 7

16. Vitamin D deficiency and pregnancy rates in women undergoing single embryo, blastocyst stage, transfer (SET) for IVF/ICSI. Polyzos N. P. et al. Human Reproduction, Vol.29, No.9 pp. 2032 –2040, 2014. doi:10.1093/humrep/deu156

17.   Vitamin D deficiency and pregnancy rates following frozen-thawed embryo transfer: a prospective cohort study. van de Vijver A. et al. Human Reproduction, Vol.31, No.8 pp. 1749–1754, 2016. doi:10.1093/humrep/dew10

18.   Serum 25-hydroxyvitamin D concentrations and treatment outcomes of women undergoing assisted reproduction. Abadia L. et al. Am J Clin Nutr 2016 Sep;104(3):729-35. doi: 10.3945/ajcn.115.126359

19.   Serum vitamin D status and in vitro fertilization outcomes: a systematic review and meta-analysis. Lv S.S. et al. Arch Gynecol Obstet 2016 Jun;293(6):1339-45. doi: 10.1007/s00404-016-4058-1

20.   The role of vitamin D in reproductive health--a Trojan Horse or the Golden Fleece? Dabrowski F.A. et al. Nutrients 2015, 7, 4139-4153; doi:10.3390/nu7064139