Is yoghurt the ultimate health food?
Can this household ingredient ward off ailments or is it too good to be true? By Jessica Bradley Can yoghurt improve your immune system? There is growing evidence suggesting yoghurt improves our immune systems via the gut, partly by lowering inflammation in the body which, over the long term, can increase the risk of diseases such as heart disease. But more research is required, says Bradley Bolling, associate professor in food science and nutrition at the University of Wisconsin-Madison in the US. “Diet-related diseases develop with – or because of – chronic inflammation, so trying to reduce it may delay the onset of, or reduce the risk of developing, chronic diseases such as cancer, type 2 diabetes and cardiovascular disease,” he says. “But most studies about disease prevention have used speciality yoghurts to deliver a probiotic microbe or cocktail of microbes, so they’re more studying these microbes, rather than a general yoghurt product.” This means, he adds, that there isn’t much evidence based on the kind of yoghurts we buy in the supermarket. But Bolling’s research – which did involve the kind of yoghurts we buy in the supermarket – found an anti-inflammatory effect from consuming 8oz of yoghurt before a large meal, which is around half a standard 500g tub. “We need additional studies which help us understand how much and how often, yoghurt needs to be consumed to have an impact. Also, we don't have a good understanding of how the molecules or microbes that have these effects vary in yoghurts available to consumers.” Bolling is now conducting studies involving humans to try to understand the mechanisms behind how yoghurt may hinder chronic inflammation. Could yoghurt stop you developing type 2 diabetes? Research on the effects of eating yoghurt on the risk of developing type two diabetes has produced mixed results. In 2017, scientists reviewed 13 studies that looked into the potential effects of yoghurt consumption on the risk of developing type 2 diabetes and found strong evidence that suggests a link between the two. Another review of studies looking at the consumption of dairy foods in general and type 2 diabetes found a ‘possible’ relationship. However, in another study, researchers analysed studies that looked into the effects of probiotic yoghurt on their effects on blood sugar levels in people with type 2 diabetes and found no benefits of consuming probiotics compared with conventional yoghurt. This spiced roasted cauliflower with lentils and tahini yoghurt contains plenty of nutrients and vitamins Breast cancer It is thought that one of the causes of breast cancer may be inflammation in the body, triggered by harmful bacteria, says Rachael Rigby, senior lecturer in biomedicine at Lancaster University. Rigby and her colleagues theorise that yoghurt may be protective against this. Natural yoghurt contains lactose-fermenting bacteria similar to the bacteria found in the breasts of mothers who’ve breastfed, which is known to lower the risk of breast cancer by 4.3% for each year the mother breastfeeds. “There is an abundance of evidence showing that good bacteria are associated with preventing cancer,” Rigby says. Although, she adds, it’s difficult to know for sure. For instance, someone with a diet high in foods that contain and promote good bacteria may also be more likely to have other healthy habits lowering their risk of cancer. “Evidence shows that breastfeeding reduces incidents of breast cancer, there have been many studies across different settings, communities and geographical settings that have reproduced these same findings,” Rigby says. “The theory is that eating lactose-fermenting bacteria found in natural yoghurt can have a similar protective effect. But it’s very difficult to rule out other variables.” But how much yoghurt is needed to reap these health benefits? “It’s about consistency and longevity, rather than amount,” Rigby says. “Little and often is often better than consuming a bucket of yoghurt in a day.” These natural yoghurt recipes are full of nutrients Mango lassi chia puddingBarbecued salmon skewers with raitaQuick vegetable curry Mango lassi chia pudding Barbecued salmon skewers with raita Quick vegetable curry Mental health There’s evidence that the live bacteria found in yoghurt can improve mood. In 2015, researchers divided 70 people into three groups. They gave one group 100g of probiotic yoghurt (containing live bacteria), one placebo capsule, or one probiotic capsule and conventional yoghurt. Those who consumed probiotics in yoghurt or capsule saw benefits to their mental health. Then in 2017, a study involving mice showed that this mood-boost may be down to Lactobacillus, a probiotic found in yoghurt. Researchers from the University of Virginia School of Medicine looked at the gut microbiomes of mice who’d been subjected to stress and found that they lost Lactobacillus. With this, came depressive symptoms. When they were fed Lactobacillus, they almost returned to normal – which led the researchers to conclude that a single strain of Lactobacillus was enough to influence mood. They found that, when levels of Lactobacillus are decreased in the gut, the level of kynurenine, a metabolite in the blood that research has shown to drive depression, increases. In 2023, a follow-up study at the university saw similar results. Of course, mice are different to humans, but could further research suggest the same applies to us? The scientists involved in the study believe so, with researcher Andrea R. Merchak explaining: “With these results in hand, we have new tools to optimise the development of probiotics, which should speed up discoveries for novel therapies.” The type of yoghurt impacts the health benefits Unsweetened options such as natural yoghurt, Greek yoghurt and kefir (which isn’t technically a yoghurt but a fermented dairy product) are linked to positive health due to the presence of probiotics without additives. Dairy-free yoghurts are made from plant-based milk alternatives, such as soy, almond, coconut, oat, or cashew drinks. Almost all plant-based yoghurts undergo fermentation, where the same bacterial starter cultures are used to ferment them before other ingredients are added to give it a texture like dairy yoghurt. But some dairy-free yoghurts are heat-treated, which can kill live bacteria, so it’s important to check the label to make sure it contains live cultures. As for sweetened yoghurts, there has long been concerns among health experts about the sugar content in yoghurts. “We found that the categories with the most sugar were yoghurts marketed at children and organic,” says Bernadette Moore, professor of nutritional sciences at the University of Leeds. But these yoghurts still have some healthy credentials, says Moore. “If a parent is deciding between a sugar-sweetened beverage and a sweetened children’s yoghurt, the yoghurt will still have calcium, vitamin D and protein, so it’s the better choice,” she says. Tempted to now add yoghurt to your shopping basket? Look for yoghurts with plenty of live bacteria. But says Rigby, that doesn’t mean yoghurt has to be an expensive addition to your diet. “Cheap, bog-standard natural yoghurt that you get in big pots,” is perfect she says. “They naturally tend not to have as much sugar in as well; a lot of sugar might counteract any health benefits.” Originally published February 2024