I’ve just been on a quick trip across the “fertility” section of the internet and returned with an abundant supply of pineapple cores, pomegranate juice and Brazil nuts. But is there any science behind these “fertility foods”? And do any of them help to improve your fertility or chances of success with IVF?
It’s important to note that no one (to my knowledge) is saying that “fertility foods” are a replacement for fertility treatment. Instead, they’re meant to aid women who are trying to conceive but haven’t been diagnosed with fertility problems, and for women (like you) who are undergoing fertility treatment and want to improve their chances.
Here are some of the most frequently mentioned “fertility foods”, and what they’re supposed to help with:
Pom juice is supposed to beef up the lining of your uterus, improve blood flow (including blood flow to the uterus), and improve sperm quality. I’ve scoured and scoured and scoured, and there’s basically zero evidence for any of this. Everything is supposition: “Because pomegranate contains such-and-such vitamin, we imagine it might help with x.”
Pomegranate does contain lots of antioxidants, which can help to neutralise those pesky free radicals (which speed up the aging process of your eggs), but so do lots of other brightly coloured fruit and veg.
And while I wouldn’t want to encourage your inner cynic too much, bear in mind that the popularity of pomegranates as a “wonder food” emerged at the same time as a massive PR campaign by POM Wonderful – which makes and sells pomegranate juice.
Pineapple contains bromelain, which helps to prevent blood clots and reduce inflammation. It’s recommended for people with arthritis (because of its anti-inflammatory properties) and those who’ve suffered from sports injuries (because it helps with swelling and bruising), among others.
According to some, bromelain is also useful for people trying to conceive because its anticoagulant properties (which prevent blood clots) mean it could help with blood flow to the uterus. Improved blood flow makes the uterus healthier and a better environment for implantation to occur. Women are usually given specific advice to eat the core of the pineapple (after embryo transfer), because that’s where the bromelain supply is most plentiful.
But is there any evidence that bromelain actually does what people claim it could do? No.
Brazil nuts are an excellent source of selenium, which is necessary for the formation and development of sperm. A very small 1998 study (69 participants) found that when sub-fertile men were given selenium supplements for three months (100 micrograms per day – equivalent to 1.5 Brazil nuts), their sperm motility increased significantly.
While 69 participants is a very small sample indeed, this evidence is more convincing because we already know that selenium is necessary for sperm health (whereas with pineapple, for example, we don’t necessarily know that bromelain is necessary for uterine health).
As for women’s fertility… recent research discovered that levels of selenium and proteins containing selenium were higher in large, healthy ovarian egg-containing follicles – which in turn might mean that selenium is important for follicle health. I have no idea whether the selenium we eat translates into the selenium produced in our ovaries (in the same way that eating a large amount of cholesterol doesn’t necessarily mean we have high levels of “bad” cholesterol in our bodies), but I guess there are worse things in life than eating a couple of Brazil nuts a day.
Unless you’re allergic to nuts.
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Waaaay back in the 1990s (think Boyzone, Take That and Alanis Morisette in her heyday), a single study was conducted by the Harvard School of Public Health into the impacts of dairy on women who’d attempted pregnancy or become pregnant during an eight-year period. The results showed that the women who consumed higher amounts of low-fat dairy products were more likely to have ovulatory infertility than those who consumed higher amounts of high-fat dairy products. The difference was even more pronounced for women who consumed high amounts of low-fat sherbet (?!) and frozen yoghurt.
I have some questions and things to say about all this.
1: Hang on… so THOUSANDS of articles suggesting that you “consume high-fat dairy for increased fertility” are based on ONE study done in the 90s?
2: Is it not possible that people who consume tons of low-fat/no-fat dairy products are more likely to have an unhealthy relationship with food in general – and are therefore more likely to be underweight or overweight? As we know, a woman’s weight has a significant impact on ovulatory infertility.
3: The study says nothing about women who don’t have ovulatory infertility, yet many articles and posts tout high-fat dairy as something that will improve everyone’s chances of conceiving. This isn’t the fault of the people who wrote the study, of course, but it still means lots of readers are being misled.
4: The writers did acknowledge that high-fat dairy doesn’t necessarily lead to better fertility outcomes: it could just be that low-fat dairy products (which are often spiked with a range of artificial ingredients and sugar) contain something that’s detrimental to fertility. If this is the case, eating a high-fat-dairy diet won’t lead to any better fertility outcomes than sticking to a no-dairy diet. I’m not saying that these other ingredients are the real cause of ovulatory infertility – just pointing out that if there is a genuine link between low-fat dairy and fertility, it might not be the “dairy” aspect that’s the problem.
5: On a similar topic, what about countries where dairy – whether high fat or low fat – simply doesn’t feature much in the national diet? Do they have higher rates of ovulatory infertility? I can’t seem to find any stats, but I’d love to know.
Avocados and olive oil
In 2012, the Harvard School of Public Health (oh, them again?) studied the fat intake of just 147 women who were mostly in their 30s and undergoing fertility treatment. They learnt the following:
- Higher total fat intake = fewer good eggs
- Higher saturated fat intake = fewer good eggs
- High polyunsaturated fat intake = poor-quality embryos
- High monounsaturated fat intake = 3.4x higher live birth rate (bear in mind this seems like a lot, but it’s from a verrry small sample size)
The lead author of the study concluded that “The best kinds of food to eat are avocados, which have a lot of monounsaturated fat and low levels of other sorts of fat, and olive oil.” Hence the onslaught of blog posts proclaiming avocados to be the new “wonder fertility food”.
But, as Dr Zoë Harcombe PhD explains when comparing a number of foods mentioned in the study, olive oil has 35 times more polyunsaturated fat (“bad”) than pork and steak. The best food for monounsaturated fat (“good”) is olive oil, but it’s also one of the worst offenders for total fat (“bad”), so… how does that work? Pork chop contains relatively little monounsaturated fat, but it’s also low in total fat, so does that make it a “good” or a “bad” food?
Avocados, meanwhile, aren’t the lowest in total fat OR saturated fat OR polyunsaturated fat – and they’re not the highest in monounsaturated fat either. The food that’s closest to the researchers’ ideal is the pork chop.
Dr Harcombe concludes: “There is no comparable desperation to a couple wanting a child and going through the agony of IVF to try to realise their dream. Telling women that they can ‘triple their chances of a live birth’ by consuming monounsaturated fat, as if this can actually be consumed in isolation from the other fats that are alleged to lead to fewer good eggs and embryos of poorer quality, is outrageous. It is ignorance to the point of cruelty.”
So where does this leave us?
“Being young” is far and away the most successful way to have a baby – whether you have fertility problems or not. You could also do with quitting smoking, as practically all scientific studies show that smoking accelerates the loss (and has an impact on the quality) of eggs.
I’ve done a ton of research into whether – and by how much – food affects your chances of conceiving, and the conclusion I’ve reached is this:
There’s no such thing as a “fertility food”. If you eat a well-balanced diet that provides you with all the nutrients humans need, your body is more likely to be healthy, strong, and have well-regulated hormone levels – which in turn gives you a better chance of conceiving. Unfortunately, “a better chance” is just that: if you’re over the age of 40, it’s not like you can reverse your odds by spending all your time and money at Whole Foods.
If you want to eat “fertility foods” because you’re kitchen-sinking this whole pregnancy endeavour, I understand. But it’s best not to go apeshit on pomegranates and Brazil nuts to the detriment of other foods that you need for a well-balanced diet: your body’s going to end up being less healthy than if you don’t eat them at all.