Last updated by Dr Sarah Brewer on
Candida yeasts live in the gut of around 70% of healthy adults. Normally, they are tolerated by the extensive immune protections present within your intestines. But many people with irritable bowel syndrome (IBS) develop symptoms for the first time after an attack of food poisoning (gastroenteritis) or following a course of antibiotics, however, which disrupt the normal balance of digestive bacteria and allow Candida yeasts to thrive.
Candida and IBS
People with diarrhoea-predominant IBS often have intermittent, persistent, watery motions, accompanied by gas distension, flatulence and abdominal pain. These are also the main symptoms caused by intestinal Candida infection. However, a link between the two has proved elusive.
A study from Addenbrooke’s Hospital in Cambridge, where I trained, was published in 1992. Stool samples were cultured from 38 patients with IBS and 20 healthy controls. Moderate numbers of Candida albicans (10,000 per gram) were grown from three of the stool samples provided by IBS patients (7.9%) but none from the controls.
These findings were dismissed as two patients had recently received antibiotics and one stool sample was delayed in transit by more than 24 hours. When these individuals were re-sampled, no Candida colonies were grown and the authors concluded that Candida was not the cause of their IBS symptoms.
These findings may seem surprising, given that Candida persists as a normal commensal in 70% of the population. Normally between 10 and 1000 fungal cells are found per gram of stool. These cells are present in a quiescent state as individual cells which replicate by budding. They have not ‘switched’ to the invasive form that produce invasive threads (hyphae) and therefore may not remain viable in stool samples that are delivered to a laboratory up to 24 hours later.
Even so, I agree that overgrowth of Candida is not the cause of symptoms in people with IBS, and that antifungal drugs are not usually helpful in reducing symptoms. Why? because active Candida overgrowth is not needed to produce IBS symptoms. Just the presence of the commensal form is sufficient to trigger IBS symptoms in some people, as a result of immune responses to their presence.
Candida and immune reactions
Candida yeasts harbour as many as 178 different proteins that can trigger an immune response Known as antigens, these proteins including components of their cell walls (eg mannoproteins) and the enzymes they secrete (eg aspartyl proteinases, enolase).
Candida antigens can trigger the production of antibodies, heighten reactions against other allergens (eg egg ovalbumin) and provoke mast cell-mediated ‘leakiness’ of the intestinal lining to provoke gastrointestinal symptoms such as diarrhoea, bloating and pain. This is not surprising, given that the majority of your immune cells are found within the lining of your small intestines, in what is known as GALT (gut-associated lymphoid tissue).
Although the link between Candida and IBS is controversial, researchers writing in the European Journal of Gastroenterology and Hepatology accept that, although the role of yeasts in IBS remains unclear, there is increasing evidence that yeasts can cause IBS-like symptoms in sensitised patients.
The best anti-Candida diet
Candida sensitivity and overgrowth can be overcome through nutritional and lifestyle changes, but it is important to avoid fad diets and over-strict regimes. As well as being difficult to follow, these make life a misery and can lead to vitamin and mineral deficiencies.
Many people are advised by well-meaning nutritionists to cut out all fruit, limit vegetables, eat almost no grains and avoid all the foods that bring pleasure in life. They rationalise that this will ‘starve’ the yeasts of sugar. Paradoxically, these strict, anti-Candida diets often make things worse and lead to deteriorating health and impaired immunity that may actually promote persistent Candida and even its overgrowth so that symptoms worsen. This is NOT a sign that the anti-Candida diet is working, as is often claimed. Quite the opposite, in fact.
Laboratory research shows that Candida albicans switches from the benign single cell form to the invasive form and grows more vigorously in lower glucose concentrations of 0.1% – similar to those found in body tissues – compared with higher concentrations of 2%. So, trying to starve yeasts of sugar in the intestines may have the opposite effect so that symptoms become significantly worse.
The best anti-Candida diet is one that boosts immunity rather than one that deprives you of adequate nutrition. The modern functional medicine approach to Candida and intestinal leakiness involves what is known as the 5 Rs approach: Remove, Reintroduce, Re-Inoculate, Repair and Rebalance.
The first step is to remove some of the factors known to trigger symptoms.
Potential pathogens such as Blastocystis hominis, Dientamoeba fragilis, Entamoeba coli, Endolimax nana and Giardia lamblia may play a role; all but Giardia can be found as commensals in the intestines of healthy people without symptoms, so their presence is often discounted. If you have diarrhoea, your doctor can arrange stool testing for you.
Candida and food intolerance
In rigorous food elimination and challenge studies, around two-thirds of people with IBS patients have an identifiable food intolerance, especially those with diarrhoea-predominant IBS. The most commonly identified culprit foods are dairy products and grains. Although expensive, IgG food testing may help to pinpoint the foods to which you are intolerant.A study by the University of York investigated the effectiveness of a three-month exclusion diet in 150 people with IBS and raised levels of specific anti-food IgG antibodies. Eliminating the identified foods provided significantly greater symptom relief than eliminating ‘sham’ foods to which participants were not intolerant.
The most commonly identified intolerances using this approach were yeast (87%), milk (84%), whole egg (58%), and wheat (49%).
In another study, IgG antibodies against 14 common food antigens in the serum were measured in 77 patients with diarrhoea-predominant IBS and 26 healthy controls. Food-specific IgG antibodies were identified in 50.65% of the IBS patients compared with 15.38% of controls. When those with IBS followed a diet that excluded the identified food for 12 weeks, all symptom scores significantly improved.
Yet another study involved 20 people with IBS for whom standard medical therapies within a specialist gastroenterology clinic had failed. They were prescribed a food elimination diet based on IgG testing and followed for one year. Significant improvements were seen in stool frequency, pain and IBS-related quality of life scores. Probiotics were also used in this trial but were deemed less helpful than the food elimination approach.
Digestion starts in the mouth, and adequate chewing is vital not just to disrupt food but to moisten it with saliva. Saliva contains two digestive enzymes, amylase which splits starch into simpler carbohydrates such as maltose and glucose, plus salivary lipase which breaks down dietary fats.
Practice mindful eating which involves savouring and really experiencing the look, smell, texture and taste of each bite as you chew it thoroughly.
Adequate fibre intake helps to discourage Candida overgrowth and can improve digestive symptoms in some people with irritable bowel syndrome – whether diarrhoea or constipation predominant. When increasing your fibre intake, it is important to drink at least two to three litres of fluid per day to bulk up the fibre and prevent your motions becoming too dry.
Many people who do not tolerate a high-fibre diet well are simply not drinking enough water.
Vitamins and minerals
The micronutrients that are most often lacking are iron, magnesium, potassium, selenium, zinc and vitamin D. If you are cutting out food groups (eg dairy) or specific foods (eg wheat) because of intolerance, you are at increased risk of nutritional deficiencies. A multivitamin supplement is then a good idea.
Biotin is a B vitamin which is important for the integrity of skin and mucus membrane linings. An estimated one in 123 people has an inherited inborn error of biotin metabolism which allows yeast infections to take hold more readily.
The most effective supplement I have found to reduce bowel spasms is magnesium.
In highly acidic conditions, Candida stays in its less invasive form as simple yeast cells that occasionally bud and divide. When acidity falls below pH 4.5, Candida stops growing. As stomach acid is normally around pH 2, any yeasts present in the food and drink you consume are either killed or suppressed. As stomach juices become significantly less acid yeasts can thrive and, at pH 6 (just below neutral) start to produce invasive threads ( hyphae). This switch from a simple-celled form to the thread form can occur within one to three hours of a loss of environmental acidity.
As food tends to stay in the stomach for around four hours, on average, any contaminating Candida yeasts present may start to overgrow when acidity is reduced.
Reduced stomach acid secretion (hypochlorhydria) can result from medication (eg antacids, proton pump inhibitors, h2-blockers), medical conditions (type 1 diabetes, gastritis), following some types of gastric surgery, and also becomes more common with increasing age.
Across Europe and the US, hypochlorhydria affects an estimated one in seven people. Very low stomach acid (achlorhydria) is present in just under 2% of people in their 50s, but in 19% of people in their eighties.
Another study found reduced stomach acid levels in as many as 69% of elderly people. several supplements can increase stomach acidity, including vitamin C (ascorbic acid) or a digestive enzyme supplement containing betaine hydrochloride-pepsin. NB Do not to use hydrochloric acid supplements with anti-inflammatory medications such as aspirin or ibuprofen which could increase the risk of peptic ulceration.
Boost bile production
Digestive enzymes and supplements that promote bile production will also help, such as globe artichoke, as bile has a strong suppressive effect on Candida albicans growth.
Probiotic, lactic-acid producing bacteria that are naturally found in the gut inhibit the growth of Candida yeasts, to improve IBS-like intestinal symptoms. A recent meta-analysis of pooled data from 15 trials, involving 1793 patients showed that probiotics significantly reduced distension, bloating, and flatulence compared with placebo.
The probiotic supplement with the best evidence to support its use in IBS is called Symprove. This non-dairy and gluten-free liquid with a Mango & Passionfruit flavour is designed to protect the bacteria as they pass through stomach acids and delivers live bacteria within the lower intestines. The 12 week program has been described as ‘life-changing’ by people with IBS. Click here to read more about probiotic supplements.
Peppermint oil is gaining acceptance as a treatment for IBS within the medical world based on its anti-spasmodic action. A meta-analysis of data from 12 trials, involving 2,500 people, compared the effectiveness of fibre supplements, antispasmodic drugs and peppermint oil in treating IBS symptoms, and peppermint oil was the most effective based on the number of people needed to treat (NNT) to prevent one from having persistent symptoms. For peppermint oil, the number was just 2.5, compared with 5 for pharmaceutical antispasmodics and 11 for fibre (6 for ispaghula).
The antispasmodic medicine, hyoscine, is available as Buscopan IBS Relief.
The final approach involves addressing your on-going diet and lifestyle to reduce the chance of symptoms recurring. In general, this means eating a wholefood diet supplying plenty of fruit and vegetables, lean protein and fibre with minimal processed and sugary foods, additives and preservatives.
You may even be able to re-introduce some of the foods to which you were originally intolerant after your symptoms have fully recovered.
Click here to read how the low FODMAP diet can improve irritable bowel syndrome.
Image credits: graham_colm/wikimedia;