Hormones

There are lots of different types of hormones, and each one has its own particular function within the body. Hormones affect many aspects of our lives include our mood, our growth, sleep cycles, metabolism and sexual development and reproduction.

Hormones are present in the body at different concentrations - some of which are really low levels, such as in the order of 'parts per billion' or 'ppb' (1 ppb is the same as 1 second in 30 years); but you also have to consider how 'strong' the effect of the hormone is. For example, 100,000 times more testosterone than oestrogen is needed to achieve the same level of hormone receptor activation.

Hormones (for example, progestogens, oestrogens and anti-androgens of steroidal structure) are prohibited from cosmetic products, so any cosmetic product containing hormones would be illegal in the UK and EU.