During the winter months, many of us are vitamin D-deficient.
Our bodies create it using sunlight and it’s fundamental for fertility and pregnancy.
It affects your sex hormones - if you don’t have enough it’ll reduce your sex drive - and it’s been linked to ovulation disorders and PCOS (polycystic ovary syndrome).
Although you can get some vitamin D from food (egg yolk, fortified foods, oily fish, red meat) the best way is through a supplement. The Department of Health recommends everyone over 5 years old takes 10mcg a day from October-March/April.