We have heard many, many times about the disastrous effects of sugar on our natural fertility. ‘Disastrous’ sounds quite dramatic, but it is the current bad thing in nutrition circles right? Sarah Wilson, ‘I Quit Sugar’ author, Pete Evans, general paleo champion and a whole host of trainer-slash-tv-show-celebrities will be back me up here.
And it seems rightfully so.
For natural fertility, sugar is frequently cited as being responsible for increasing inflammation (especially in women with endometriosis), altering hormone levels such as progesterone, estrogen and androgens and increasing insulin resistance which has its own collection of negative consequences.
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But what about the impact of sugar on IVF success? Unsurprisingly there is only an incredibly limited number of randomized control trials looking at the impact of sugar on IVF success rates. Is that because it’s generally understood that of course sugar negatively impacts IVF? If so, why isn’t that information fed to us (pardon the pun) in the fertility clinics in a very clear way? Or is it because there are no funding bodies willing to pay for such a trial? Or perhaps it’s thought to play very little of a role at all. Regardless of the reason the outcome is still the same. More evidence is needed.
For those of you who have read my free ebook (and those of you who haven’t, why not? Did I mention it was free?) you will know that I am a big believer that despite all the medications, medical procedures and laboratory techniques that IVF utilizes as ‘patients’ we are still active in that process. That is despite the fact that your body is about to be highjacked by all sorts of medications you still have control over what you eat, drink and the way you live your life.
That is NOT to say that if we have a bad cycle with skyrocketing estrogen, 50 antral follicles developing and only one lead follicle that eating the right food is going to save the day, but in a more moderate situation modifying diet and lifestyle factors have been shown to have a significant impact on IVF success rates (1). As we know Lady Luck also has her hand to play in the IVF cycle – so perhaps modifying those lifestyle factors can be considered a bit like buying extra lines in the lottery rather than just the standard ticket.
Its not just monkey business
So back to sugar and IVF.
Like I said, there is insufficient information examining the exact impact of sugar on IVF success. Interestingly though in 2014 a study conducted on rhesus monkeys was completed (2). I know, a human study would have been preferable but don’t we share over 90% of the same DNA with primates?
What the scientists did was get a group of monkeys and divide them into two separate groups. Over a period of six months one group was given extra sugar in their diet and the other group was not. I know, try and suspend that part of your brain that is telling you this is a step back for animal rights.
They then did a stimulated cycle, very similar to that of an IVF cycle and compared the outcomes of the monkeys that were given sugar against those that were not. What they found was that when they did an egg collection, after six months of eating extra sugar, although overall the number of eggs collected was similar between the two groups, significantly less mature eggs were able to be collected in monkeys that had been given extra dietary sugar versus those that were not (18.5% of eggs were mature in the sugar group versus 86% mature in the non-sugar group). It is believed the sugar interfered with how the eggs were able to mature. This is obviously concerning as fertilisation and production of a viable embryo is not possible without eggs first developing to maturation. And because I know you are thinking it, the extra sugar that these primates were taking wasn’t even that high with researchers reporting that it was in fact the equivalent of less than half of what most women in the U.S. would consume.
Although this is only a small, elementary study completed in monkeys it is one of the first to particularly look at the direct relationship between sugar and IVF cycle outcomes. It is therefore absolutely worth noting and women undergoing IVF could do worse than to simply reduce the amount of sugar they intake.
A human study this time
Another study was also done (3), this time in humans, looking at the relationship between carbohydrate intake (and as we know, sugar is a simple form of a carbohydrate), protein intake and IVF outcomes. Although this was only a small study – only twelve women participated, so yes, there is plenty of room for these results to be skewed – they found huge differences when women aged 35 or younger and with a BMI of 26.5 or less modified these two food groups.
After being unsuccessful for one of their IVF cycles, these women waited at least two months before commencing another cycle. In between these IVF cycles the women focused on reducing their carbohydrate intake and increasing their protein intake (these women had dietary support and were guided on how to do this) and found that blastocyst formation increased significantly as did clinical pregnancy rates – from 16% to a whopping 83%.
All in all, this led the authors to summarise that
Seemingly young healthy patients with poor embryo development can possibly increase the percentage of blastocyst formation by increasing their daily intake of protein and lowering their daily carbohydrate intake 2 months prior to their IVF cycle. – Russell et al 2012
And for ladies over 35…
Dr Russell repeated this kind of study on 120 ladies who were aged 36 and 37. As reported by Kate Johnson for Medscape, these ladies were categorised depending on whether their diet consisted of high amounts of protein (over 25% of their food intake) or low amounts of protein (under 25%). It was found that ladies who were in the ‘high protein’ group had better rates of blastocyst formation (64% vs 34%), clinical pregnancy rates (66% vs 32%) and the holy grail of IVF treatments, live birth rates (58% vs 11%) .
Additionally, when protein was greater than 25% coupled with carbohydrate being less then 40% the clinical pregnancy rate skyrocketed to 80%. I think that is AMAZING.
Dr Russell concedes that although from the data presented here it seems as if a high protein, low carbohydrate (and that includes sugars) diet is the way to go, the underlying mechanisms is unknown. Is it the actual grains that causes this change or is it another factor such as a possible inflammatory effect of gluten (have a look at my post on gluten if you haven’t already)?
Before you start throwing out all the pastas, breads and cookies from your pantry remember that changing your diet when imminently about to commence an IVF cycle is not necessarily about weightloss (you don’t want to drastically alter your weight without your fertility doctor being aware of it as it may change your medication regime) but is about making sure you are eating the optimal foods to assist in the production of healthy eggs and ensuring that there is a healthy environment to welcome any little embryos. The women in these studies also had help from nutritionists to help them get their balance just right. Likewise, before you make any drastic changes to your diet it would be prudent for you also to get this type of advice – or even just speak about it with your doctor or fertility nurse. In the meantime though, it is safe to say that I would definitely rethink that afternoon Mars Bar.
- Gormack, A., Peek, J., Derraik, J., Gluckman, P., Young, N. & Cutfield, W. (2015) Many women undergoing fertility treatment make poor lifestyle choices that may affect treatment outcome. Human Reproduction, 30 (7) 1617–1624
- Chaffin, C., Latham, K., Mtango, N., Midic, U. & VandeVoort, C. (2014) Dietary Sugar in Healthy Female Primates Perturbs Oocyte Maturation and In Vitro Preimplantation Embryo Development. Endocrinology 155 (7)
- Russell, J., Abboud, C., Williams, A., Gibbs, M., Pritchard, S. & Chalfant, D. (2012) Does changing a paitents dietary consumption of proteins and carbohydrates impact blastocyst and clinical pregnancy rates from one cycle to the next? Fertility and Sterility. Sup 47 O-153.