I usually like to focus on what you can eat while TTC, rather than what you should limit. And in general, I believe that food rules can be damaging and all food can be included in moderation. But there is one nutrient that I make an exception for, so far as to say, just don’t eat this if you’re TTC.
And that’s trans fat.
When it comes to nutrition very few pieces of dietary advice are ever clear-cut, except this: trans fats are unequivocally unhealthy. There is no safe level of industrial produced trans fats intake.
Trans fats are naturally found in small quantities in dairy, but the trans fat of concern is actually a slightly different structure. It is produced commercially by partially hydrogenating vegetable oils, that is, changing their structure to make them solid at room temperature. This is done to add crunch and crispiness and to extend shelf life.
Trans fats increase inflammatory markers, inflammation throughout the body (which is known to have a negative effect on egg health) and increase insulin resistance (which can negatively affect ovulation.)
Studies have shown a negative impact on fertility in both “natural” conception and in assisted reproduction.
The Nurses Health Study found that for every 2% increase in trans fats (as opposed to carbs or unsaturated fats) there was a 73% increased risk of ovulatory infertility. A recent North American study was consistent with these findings but found the impact on all types of sub-fertility, not just ovulatory infertility.
In IVF, one study found increased trans fats was associated with poor outcomes including lower fertilization rate, blastocyst conversion rate, and number of usable blastocysts and embryos. Another found higher blood levels of trans fatty acids was associated with a greater implantation failure rate and lower live birth rate. In fact, trans fat intake has been independently associated with increased fetal loss.
As a rule I don’t think any nutrient or food should be demonised. That is not the case with trans fat. I don’t think they should be allowed to be used in food at all and I think everyone – especially those TTC or pregnant- should be avoiding them as much as possible. It’s a big ask but as much as possible, don’t eat this if you’re TTC.
Download my comprehensive guide to avoiding trans fat here. (And don’t worry, it’s not all bad news for sausage rolls!)
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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.