Food affects my vagina? Wait what?!

The hidden impact of UPF that nobody's talking about

Jun 12, 2025

sliced apple — Photo by Louis Hansel on Unsplash

I’m pretty sure most of you reading this will have heard of the human microbiome - but just in case - it’s the collection of bacteria, viruses, fungi and more, that live on our skin and inside all of our bodies, playing a huge role in human health that is only just beginning to be understood. The most commonly talked about microbiome is the one in our guts, and it probably goes without saying that I’ve written a lot about this particular colony in Ultra Processed Women - because what we eat is quite obviously going to have some impact on everything that’s going on in our digestive system.

One area of the microbiome that you’ve probably heard less about though is the one in your vagina. The vagina has its own unique microbiome: a little colony of mostly one genus of bacteria, called lactobacillus. Whilst a healthy gut microbiome is thought to be one with as many species as possible, a bit like a rich and thriving rainforest; in the vagina, the opposite is best: you are aiming for simplicity. Just a handful of different types of lactobacillus, whose role is to produce lactic acid, serving as a protective barrier against pathogens and maintaining a balanced ‘ecosystem’.

If I asked you how you could upset the balance of your own vaginal ecosystem, you might come up with some ideas: fragranced soaps, perfumes, or maybe even antibiotics. But what’s absolutely crucial, and perhaps less obvious, is that this vital little colony is influenced by what you eat.

Not only this, but the difference between a healthy and ‘dysbiotic’ vagina - one whose resident colony are unhappy - could potentially have a huge impact on multiple areas of women’s health.

Although we tend to think of different microbiomes in our bodies as separate entities - the skin, the nose, the mouth, the gut, the vagina (and possible other microbiomes for example the brain) - they are of course all connected and functioning parts of a whole. In our guts, we have an oestrobolome - this is a special collection of bacteria that are capable of metabolizing and modulating oestrogen.

In the book, I’ve nicknamed this part of our microbiomes the Sea Witch, because although there’s nothing evil about it, it somehow conjures up an image for me of Ursula from the Little Mermaid, controlling what happens nearer the surface from way down in the murky depths.

An oestrobolome that’s functioning optimally, and maintaining optimal oestrogen levels, is incredibly important for women’s health. And what does the Sea Witch need for this optimal performance? She needs a diverse gut microbiome, and the key to this is a diet that’s rich in vegetables, fruit, whole grains, nuts, seeds, berries, herbs, beans and pulses – plant fibre, basically, which happens to be the stuff you get less of if you’re eating a lot of UPF.

And as the food you are eating affects your oestrobolome, this in turn affects your oestrogen levels, which in turn affects the lactobacillus in your vagina.

The lactobacillus in your vagina is not fixed, even when you are in optimal health - it changes with age, during pregnancy, and with the menstrual cycle. Before puberty, and after menopause, for example, the population of lactobacillus decreases, but if you take HRT it is restored to pre-menopausal levels.

These fluctuations are because the lactobacillus ‘feed’ off something called glycogen, and glycogen goes up when levels of oestrogen are higher, and down when they are lower – it’s all under the control of the Sea Witch, basically.

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If you’ve ever had thrush you may have already tried to heal issues in your vagina by changing your diet - many women try high wholefoods and low sugar - although the conventional path from your GP is more likely to be focused on anti-fungal tablets or cream. But researchers have shown that the marvellous lactobacillus are great at inhibiting the growth of candida - the fungi that causes thrush. So by reducing UPF and upping your intake of plant fibre, you may be able to up the lactobacilli in your vagina, and this in turn will help combat thrush.

Twenty to thirty percent of women suffer from bacterial vaginosis (BV), another female health issue that isn’t brilliantly understood but which is very unpleasant. If you have symptoms (these include burning, itching, and a fishy smelling discharge) you’re likely to get the same treatment women have been given for the past fifty years – oral or topical antibiotics – and in around 80 per cent of cases, it will come back.

If you’ve noticed your BV symptoms fluctuating, perhaps with your menstrual cycle, this is almost certainly connected to the oestrobolome, and the shifting levels of oestrogen providing more or less glycogen to keep your lactobacillus colony happy. If the colony is depleted, bingo, your vagina’s defences are lowered, and the resulting BV can have serious ramifications, including sexually transmitted infections, pelvic inflammatory disease, and even pregnancy complications, such as waters breaking early (PROM), preterm birth, and low birth weight.

If you suffer from BV and have been asked about your diet, I’d be very interested to hear from you. Most women I’ve spoken to say it wasn’t mentioned - but it's a ‘no risk’ strategy worth exploring. I haven’t found specific evidence about UPF and BV - but one 2022 study found that an ‘unhealthy diet’, high in sugar and fat and low in fruits and vegetables, raised the risk.

A happy vaginal microbiome with its well-balanced lactobacillus community may also reduce the risk of HPV infection (Human Papillomavirus) that is recognised to cause cervical cancer. Vaginas with higher numbers of certain strains of lactobacillus have been shown to clear HPV more efficiently, whereas vaginas with low lactobacillus and with some of the strains associated with BV have higher rates of HPV infection and persistence. This same vulnerability caused by low lactobacillus may well extend to other viruses, for example HIV, the virus that can progress to AIDS.

And the health of the vaginal microbiome is also directly related to issues such as Urinary Tract Infection (UTI), because the initial step for the infecting bacteria is to colonize the entrance to the vagina. If the vagina is high in those fabulous lactobacilli, then their low pH will zap the pathogens before they even get going on their unpleasant plans for your urethra, bladder and kidneys.

The fact that there’s a connection between bacterial infections and bacterial colonies may make some intuitive sense, but interestingly there are also emerging links between gut and vaginal bacteria and other women’s health issues that may not seem quite so obvious, such as PCOS, uterine fibroids (UF), endometrial cancer and endometriosis. Researchers have found differences in the gut, vaginal and endometrial microbiomes of women with endometriosis, and a number of studies have shown that diet could improve the condition. These studies have recommended eating less red meat and trans fat (the latter is banned in the USA but still found in UK products such as UPF pastries, cakes and biscuits under names like ‘hydrogenated fat’, ‘partially hydrogenated oils’ and ‘mono and diglycerides of fatty acids’), and more plant-based fibre – yes, I know I keep saying this, but it’s crucial to remember: plant fibre improves the diversity of our gut microbes and helps keep our oestrogen levels regulated.

Similarly, researchers investigating PCOS and endometrial cancer have found changes in the microbiome, and in the case of fibroids have shown that increased intake of vitamin D slows their growth because of its improvement of gut microbe diversity. Future treatments for all these conditions, they say, will almost certainly involve manipulation of the microbiome – but in the meantime, you are of course able to manipulate it yourself, by replacing the UPF in your diet with wholefoods and plants.

If you have had a health issue and been told or not told about how what you eat may be having an impact, I’d be very interested to know! The comments are open to all today (usually paid subscribers only), and I look forward to your thoughts and experiences.

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