We know that high intakes of sugar impact our fertility. But what about the intake of soft drinks specifically? Are soft drinks bad for fertility?
The Nurses Study found that the consumption of 2 or more soft drinks of any kind per day was associated with increased risk of ovulatory infertility (that is, infertility caused by an irregular of ovulation).
On the other hand, another study found that sugary soft drinks did not appear to affect ovulatory function. They did find that sugary soft drinks (≥1 cup/d compared with a lower intake) were associated with increased oestrogen levels, which is sometimes linked with fertility issues.
Most other studies seem to back up the results of The Nurses Study.
A study in couples planning a pregnancy in North America found that both female and male intakes of sugary drinks were associated with reduced fertility. When ≥ 7 drinks were consumed per week compared with none, female fertility was decreased.
Fertility was even worse if these beverages were sugar-sweetened soft drinks, including at levels as low as 2–6 serves per week. Interestingly there was little association between diet soda consumption and fertility in this study.
A study in women undergoing IVF provides us with even stronger evidence of the harm of sugared soft drinks on fertility. They found that higher intake of sugary soft drink was associated with lower total, mature, and fertilised eggs as well as good quality embryos.
Most importantly, compared to women who did not drink sugared soft drinks, women who did had low rates of both clinical pregnancy and live birth. If women drank 0.1–1 cups/day or >1 cup/day were they were 12% or 16% less likely to have a live birth than women who drank no soft drinks.
It has been suggested the link between soft drinks and fertility is driven by the effect of sugar on blood sugar levels and insulin resistance.
You can read more about blood sugars and fertility here, but briefly, insulin resistance is known to affect reproductive hormone levels which so can impair ovulation.
High blood sugars also lead to oxidative stress, which can harm egg health. The results of the IVF study discussed above seem to support this idea.
Exposure to bisphenol A (BPA), in the lining of soft drink cans and might also be a factor. It’s been suggested that it likely plays a small role here, as otherwise diet soft drink would have more of an impact. I’ll do a blog post on how environmental toxins, like BPA, affect fertility soon.
As part of your daily life, I’d say it’s best to avoid sugary drinks, especially sugary soft drinks. The research shows up that even 2 cups a week or 0.1 cups per day is likely too much.
But if you want to have one occasionally?
Like all things, once in a while will probably not harm your fertility. On these occasions, I’d recommend juice over soft drink and if possible trying to have them with a meal containing some fat and protein and not too many other carbs. This will help prevent an extreme spike in blood sugar levels.
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Fertility dietitian, ovulation expert, lover of food and squishy newborn baby cuddles. I help people get pregnant (fast) and have the healthiest pregnancies possible.