Sugar and female reproductive health and fertility

How sugar may or may not influence our health has been a topic of much interest and research over the years.

One area of health that can be significantly affected by dietary and nutritional factors is reproductive health and fertility (both male and female). Sugar is one such nutritional factor.

But how? Let’s review what the evidence tells us regarding the impact of added sugars on female reproductive health and fertility.

What is sugar?

Firstly, we need to be clear what sugar actually is. 

Sugar is classified as a type of carbohydrate. The basic building blocks of carbohydrates are monosaccharides, and the number of these vary between different carbohydrates. Complex carbohydrates and starches are made up of long chains of monosaccharides and simple carbohydrates are made up of one or two.

Why is this relevant? Because the number of monosaccharides determines how (and how quickly) the body breaks them down into glucose to be used (or misused) by the body.

There are many different types of sugars on the market including white, brown, raw cane, icing, molasses, date, honey, maple syrup, agave nectar, coconut, rapadura, muscovado and panela. Sugar in foods and drinks can also be called glucose, sucrose, fructose*, dextrose, galactose, lactose and maltose.

Quite a list!

However, to the body, all of these are just a type of simple sugar and will they be digested, absorbed and used in the same way. (*NB: fructose is processed differently, as it is mainly handled by the liver).

Do we need sugar?  

Humans absolutely need glucose to survive – glucose being the unit that the body ultimately breaks all carbohydrates down into for use. 

However, nutritionally the body does not need excessive amounts of simple added sugars as it can still make glucose without having them in the diet. So, if the body can survive (and often thrive) without a lot of simple added sugars, it makes sense that eating or drinking too much can lead to imbalances and health issues for many people.

How can sugar affect female reproductive health and fertility?

Excessive sugar intake can adversely affect female reproductive health via the different systems and organs that work together to regulate reproductive function.

These systems and organs include:

• sex steroid hormones (oestrogen and progesterone)
• reproductive tissues and organs (uterus, endometrium, ovaries)
• thyroid gland and hormones
• gastrointestinal tract and liver
• antioxidant pathways.

Too much sugar can cause imbalances in these organs and tissues, with the underlying processes driving these imbalances being oxidative stress (an imbalance between free radicals and antioxidants in the body), inflammation and insulin resistance (impaired response of body to insulin resulting in high blood glucose levels).

So, what are some of the reproductive health outcomes associated with excessive sugar intake?

Research that has looked into this has found outcomes including

• steroid hormonal imbalances
• dysmenorrhoea (painful periods)
• ovulatory infertility (not conceiving due to ovulatory issues)
• reduced fecundability (probably of conceiving).

Also, following IVF ovarian stimulation there were

• lower numbers of total, mature and fertilised oocytes
• lower number of total and retrieved embryos

and

• lower clinical pregnancy and live birth rates
• higher rates of pregnancy loss.

(The amounts of sugar ingested in these studies ranged from levels of 41.5-72g daily [equivalent to 9-16 tablespoons] to 7 or more sugar sweetened drinks per week. Remember, sugar intake includes what we add to foods and drinks and what is in processed and packaged foods).

Overall, the current evidence indicates that excessive sugar intake can have significant, clinically relevant, adverse effects on female reproductive function, health and outcomes.

(References available on request).