This topic may be slightly out of my normal 'scope of practice' as a nutrition student, but having seen it make its appearance on social media quite a bit recently I thought I better write a post about it to set the record straight. Do a quick Google search for ‘candida overgrowth’ and you will find hundreds of websites claiming to have the cure for yeast infections, gut dysbiosis, and sugar cravings. Go one step further by clicking on any of the search results and you will read about the Candida Diet, which may seem like it has some element of truth to it but is actually not founded on any kind of rigorous evidence base.
What is ‘Candida’ and what do people mean when they refer to it?
Candida is a term that refers to a genus of yeasts. Some species within this family can cause infections in certain circumstances and others just form part of a normal, healthy gut microbiome. Medical literature widely discusses Candida overgrowth, usually referring to Candida albicans as the most important opportunistic fungal pathogen in humans. It’s really important to note that these kinds of invasive Candida infections are actually life-threatening and are mostly observed in severely immunocompromised individuals including HIV/AIDS, cancer, ulcerative colitis, and gastric ulcer patients, individuals who have had invasive abdominal surgery, and burns patients. Less severe infections involving Candida include thrush, vaginitis, and urinary tract infections, and although they may not be particularly pleasant, they are very easily diagnosed and in most cases are easy to treat.
Why is ‘Candida overgrowth’ so controversial?
Despite what many alternative (and even some more 'conventional' Western) practitioners may promote, there are actually no robust, well-designed studies that have shown the link between Candida overgrowth and the non-specific symptoms that it has been linked to, including 'leaky gut', brain fog, bloating, skin problems, and fatigue. In fact, the only research that I could find that linked any kind of dietary component and Candida was performed in Petri dishes and mice. These studies suggested that coconut oil is potentially beneficial in killing the yeast, but it’s really important to note that even if an animal- or lab-based experiment show something like this, it by no means can be applied to humans.
In 1983 a book titled The Yeast Connection written by Dr. William Crook was published, in which he referred to something called Candida ‘syndrome’. He claimed that undiagnosed yeast infections were responsible for the vague symptoms already mentioned above, as well as things like food cravings, mood disorders, and auto-immune conditions. Other than anecdotal evidence, which has some value but is one of the weakest forms of evidence (here's a pretty good illustration of this to help you better understand what I mean) and should never be used as a blueprint in practice, his claims have no substantial evidence to back them up. I think the big red flag for me is that there have been no good quality studies performed since the book was published over 30 years ago to support his claims, which is a bit suspicious to me. Surely if they are all true, this would be a truly revolutionary discovery?
Here’s the thing, non-specific symptoms and problems such as eczema and chronic fatigue syndrome, which are not well understood by the medical world are a great target for nutribollocks and ‘solutions’ put forward by unqualified people that have no scientific backing. I have so much empathy for any of you who may have felt like you had to follow this diet to be 'clean' and prevent the recurrence of things like thrush because when you’re feeling crummy and just want to feel better, anything that seems to be a plausible solution is welcomed. I sure believed it. I even tried to kid myself that it worked when in fact it spurred on some pretty disordered eating behaviour and didn't do my digestion any good. The reality is that these symptoms really are ‘vague’ and can be attributed to so many different things. For example, brain fog cannot be measured on any kind of objective scale, exhaustion is more likely going to be due to late nights or a stressful lifestyle, and bloating and gassiness can be caused by anything from eating a large meal to IBS.
The Candida diet and disordered eating behaviour
The Candida Diet is incredibly restrictive. It calls for the elimination of all forms of carbohydrate and sugar, fermented foods, mushrooms, and anything containing yeast. Advocates claim that sugar feeds candida, but rarely give sound reasons for cutting out the other foods such as mushrooms. I giggled when I read the following paragraph in The Angry Chef’s post on this topic:
So what’s the big deal? Firstly, by cutting out foods that contain some kind of carbohydrate, you’re automatically cutting out pretty much all great sources of dietary fibre. This seems a bit counterproductive since we know that dietary fibre and prebiotics are incredibly important to feeding and establishing a healthy gut microbiome. Secondly, this kind of dietary restriction is designed to create anxiety and fear that consuming certain foods will either ‘cause’ or ‘trigger’ Candida. This is very disordered, creating a whole host of arbitrary rules that are not going to be healthy in the long run.
What does cause thrush?
- Long-term antibiotic use: Broad-spectrum antibiotics kill of gut bacteria, but have little effect on Candida due to the fact that it is not a bacteria. When it is allowed to dominate over the gut environment, it can cause irritating infections. This is why you're often encouraged to use a probiotic when you're put on a course of antibiotics, although we don't really know yet which strain(s) are most useful in this application.
- Oral contraceptives: Anecdotal evidence suggests that oestrogen oral contraceptives are associated with increased risk of recurrent vulvovaginal candidiasis. I struggled to find evidence support this, but managed to find this paper documenting an in vitro and in vivo experiment that involved investigating the effect of oestrogen on C. albicans isolated from the vaginal microbiome.
- Using perfumed soaps, gels, tampons, sanitary pads, washing powder, and fabric softeners.
- Pregnancy, uncontrolled diabetes, stress, and lack of sleep don't cause it, but can all make you more susceptible to infection.
How can it be tested and treated?
The only person that you should trust to test and diagnose you is a qualified medical doctor, whether they practice from a conventional Western or functional medicine perspective. Registered Dietitians and Registered Nutritionists can help you make sustainable, healthy changes to your diet for long-term health and well-being, but cannot test, diagnose, or offer treatments for Candida-related infections. Anyone else that claims to be able to test for and treat Candida that is not a qualified medical professional should set off alarm bells in your head, because I can guarantee you that these tests and treatments are not going to be based on any kind of science (and are actually a little bit dodgy).
If you suspect that you have thrush, or are suffering from gastrointestinal or urinary discomfort:
1. Find a trustworthy GP who will listen to you and will take the time to rule out any other red flags that could be causing your symptoms before they diagnose you. They should take a full medical history and may perform a pelvic exam to see what's going on down there. Depending on what they see they may collect some cells you’re your vagina that can be cultured in a lab for a proper diagnosis. Once they’ve done that, listen to the advice that they have to share with you – they are qualified for a reason. There are very specific guidelines here in the UK that medical professionals use when assessing patients for candidiasis, and have been designed according to robust evidence.
2. Get hold of a good-quality antifungal medication (whether it's in the form of a tablet, cream, or pessary) from your GP. Please don’t be ashamed or scared of using it. I find that there is a lot of shame around the use of conventional medicine, particularly amongst those who lean more towards the alternative medical model. There are few feelings that are worse than walking around for days and weeks with an itch down there and a burning sensation when you pee, so please get medical help if you're suffering.
3. If you want to adopt alternative therapies along with conventional treatment, do yourself a favour and find a registered dietitian or nutritionist, functional medical practitioner, or alternative therapy practitioner who actually knows what they’re talking about. There are some amazing food compounds, essential oils, and supplements that have the potential to support your healing process, but it’s really important to work alongside someone who is trustworthy and qualified.
4. Don’t follow a crazy diet. Rather focus on eating a balanced, healthy diet consisting of veggies, whole grains, plant- or animal-based proteins, nuts, seeds, dairy products, and the occasional ‘treat’ (I’m not a huge fan of using this word, but I'm sure you know what I mean). Stop following restrictive eating plans that promise to be the solutions to all of your problems, and rather find what actually works well for your body.
Why does this matter to me?
I suppose I've written this post to shed some light on the misinformation that exists around this topic and to say that even I was in the position to believe it once, even when I first started studying nutrition. I have had periods of fearing conventional medicine, having bought into the idea that seeking professional medical help and pharmaceuticals to cure things like thrush or urinary tract infections was ‘bad’ or ‘harmful’, and that I was not doing enough to help my body get rid off the bug and heal itself 'naturally'. The reality is that the prevalence of misinformation surrounding Candida overgrowth really can be harmful to many in that it can perpetuate fear around food, make a profit out of lies (or rather non-facts), and give people false hope of a solution to whatever health ill that they’re dealing with. I believe that eating the right kinds of foods, practicing healthy behaviours, and trying to live a holistic life is great, but not at the expense of your relationship with food, financial security, and long-term health. Finally, I just want to encourage you to not believe everything that you read on the internet and on Instagram. Start thinking a bit more critically about where you get your health, nutrition, and wellness-related information from and choose to equip yourself with knowledge that is based on evidence rather than misinformation.