Why you should know your yoghurt, and eat it daily

A new study found yoghurt cut the risk of pre-cancerous growths. But does it matter what kind?

Crammed with “good” bacteria, yoghurt has emerged as a star of gut-friendly foods. Picture: Supplied

You may have started the day with a glass of lemon water and moved on to berry-topped bircher muesli (made with almond milk, of course), but have you had the one thing that every well-informed disciple of wellbeing makes a breakfast staple?

Yoghurt, crammed as it is with “good” bacteria, has emerged as a star of gut-friendly foods — but there is more to it than probiotics. Last month researchers at the University of Washington who tracked more than 80,000 people for 25 years, revealed how eating at least two portions of yoghurt a week cuts by a fifth the risk of pre-cancerous growths, or adenoma, which can grow in glandular organs such as the prostate.

In findings published in the journal Gut they reported that among the participants, all of whom had a lower-bowel endoscopy to examine the inside of their gut, it was the yoghurt eaters who had 19 per cent fewer growths and 26 per cent fewer of the highest risk variety.

Although the precise mechanisms aren’t fully understood, the researchers believe it could be the bacteria commonly found in regular yoghurt that could work to lower levels of cancer-causing chemicals in the gut.

In this particular study yoghurt seemed to offer only significant protection for men — the researchers don’t know why — but there are many other reasons for all of us to consume it. At the Medical Research Council epidemiology unit at the University of Cambridge, researchers reported that people who consumed yoghurt regularly had a 28 per cent lower risk of new-onset type 2 diabetes than those who never ate it.

Scientists in Ireland, meanwhile, found yoghurt consumption to be associated with a higher hipbone density and a greatly reduced risk of osteoporosis in older women and men, and last year a paper in the American Journal of Hypertension showed that yoghurt intake is associated with a reduced risk of heart disease in men and women with high blood pressure.

A daily pot or two of yoghurt has also been shown to reduce bad breath and aid digestion.

However, some of the most impressive benefits have been seen by researchers looking at the anti-inflammatory effects of yoghurt. Usually, inflammatory markers in the body rise after a meal, more so when the food is high in fat and sugar. And high levels of inflammation are associated with conditions such as heart disease, arthritis and asthma.

In a study last year, Bradley Bolling, a professor in food science at the University of Wisconsin-Madison in the US, set a group of 60 female subjects, half of whom were obese, a challenge to eat sausage and egg sandwiches and hash browns. Half of the participants were asked to consume 226g of plain yoghurt — there’s usually 150g in a small carton — before the high-fat meal and results showed that it was these women who displayed lower levels of inflammation over the next few hours.

In a previous trial, published in the British Journal of Nutrition in 2017, Bolling and his team had asked some of the women studied to eat the equivalent of two small cartons of low-fat yoghurt every day for nine weeks. That trial also showed improvements in markers of inflammation for the yoghurt-eaters group, more so among obese subjects. Precisely how it works is unknown, although researchers think the yoghurt bacteria might strengthen the gut lining so that inflammatory molecules can’t leak out.

Yoghurt has also been shown to have a beneficial effect on the immune system, which could also play a part, says Dr Caroline Childs, a researcher in nutritional sciences at the University of Southampton. “Broadly speaking, yoghurt is a very good thing. It’s a useful way to get probiotics or friendly bacteria and it tastes good.”

In terms of the nutrients it contains, yoghurt is not much different from milk, being a good source of iodine, vitamins D, B2 and B12, and zinc. Ian Marber, a nutritionist, says yoghurt is a good source of protein and, like milk, also contains the “most widely available and easily absorbed form of calcium”.

Where yoghurt scores additional points is in the way it is produced. When bacteria — typically Lactobacillus bulgaricus and Streptococcus thermophilus — are added to fresh milk, they ferment the naturally occurring milk sugar lactose, which becomes lactic acid. During the process, enzymes break down lactose so that it’s more easily absorbed by the body. “Even people with a lactose intolerance sometimes find they can tolerate yoghurt better than milk,” says Dr Megan Rossi, a research associate at King’s College London and Harley Street gut health specialist.

Plain truths

Get into the yoghurt habit and it can help you to lose weight. Being protein-rich, it makes you feel more full than a carb-fest for breakfast and could ward off the urge to eat unhealthy snacks.

“There are some studies that have suggested consuming calcium-rich foods like yoghurt make it harder for the body to absorb fat from food,” Childs says, “but it needs to be plain milk yoghurt, with nothing else added to it, to have these effects.” There’s no strict guidance for how much you need, although Rossi says that most evidence points to servings of 200-250g a day of plain, natural yoghurt.

At the very worst, eating yoghurt could make you feel better about everything. “There’s growing evidence for the power of psychobiotics, specific live bacteria that when ingested have beneficial effects on mood, motivation and cognition,” Childs says. “In our trials we found that, even with careful placebo control, the mental and emotional boost from probiotic consumption was significant.”

There is a clear connection between consumption of probiotic-rich foods such as yoghurt and self-reported wellbeing. “The gut’s relationship with the brain is strong and probiotic foods boost that,” she says. “People just feel more happy when consuming them.”

What’s in your yoghurt?

GREEK YOGHURT

It’s made by straining to give it its unique, thick texture, but that removes roughly half of the calcium. Many brands put calcium back in, but check the label. On the plus side, plain Greek yoghurt contains more protein than regular yoghurt, making it ideal for rebuilding muscle following intense exercise. Many top sportspeople eat a few spoonfuls 30 minutes before bed to maximise muscle protein synthesis.

LOW FAT

Any yoghurt labelled “low fat” must contain 3g of fat per 100g or less. Full-fat dairy isn’t actually bad for you, though, and will cause no significant increase in your risk of heart disease and stroke. You will save a few calories eating this, but a full-fat yoghurt will probably keep you fuller for longer, so you’ll be less likely to overeat.

Low-fat yoghurts often have a lot of added sugar for flavour. In a study published in the BMJ last year, researchers at Leeds University found that over half of the 900 brands they tested contained 10-20g of sugar per 100g. However, three years ago, it was a daily dose of 300g of low-fat yoghurt that was shown to reduce biomarkers of inflammation in a group of women in the British Journal of Nutrition study.

KEFIR

A health staple in eastern Europe for years, this liquid yoghurt is now a favourite drink of the health brigade. It is made by covering kefir grains (available from health shops) with milk or water, and leaving them to ferment at room temperature. If made with water, sugar is needed for the fermentation process, but the sugar naturally present in milk will do the job with dairy kefir. After 12 to 48 hours, the grains are removed. Rossi says that kefir has “a much wider range of bacteria than yoghurt”. What it lacks is any strong science showing that it is beneficial to drink it. “One trial found that consuming kefir for six months improved markers of bone health in a group with osteoporosis,” she says. “And there are suggestions that, like yoghurt, it has anti-inflammatory properties.”

LIVE

All yoghurt stored in the chiller aisle at supermarkets is “live”, which simply means it contains living, growing bacterial cultures up to the use-by date. Yet there are differences between the strains of bacteria cultures used, and the terms “live” or “bio” usually means that they have been made using bifidobacteria and Lactobacillus acidophilus. Regular yoghurt is usually made with bacteria that are unlikely to survive the acidity of the gastrointestinal tract and probably won’t have much impact on gut microflora. Other bacteria, such as those used in live and bio yoghurts, are known to have more of a beneficial probiotic effect and may be helpful for people with digestive issues and symptoms of irritable bowel syndrome. Available as full-fat and low-fat varieties, “live bio” yoghurt has a smooth, creamy texture and a slightly tangy flavour.

NATURAL

This is your basic yoghurt with many of the benefits of more expensive varieties. It’s a smooth, silky yoghurt made from the traditional cultures Lactobacillus bulgaricus and Streptococcus thermophilus. It can also be made in a “set” form when cultured directly in the pot. It is, by its nature, a “live” yoghurt, although may not be labelled as such because it doesn’t contain additional bacteria thought to have specific health benefits. “Plain, natural yoghurt is as good as anything,” says Childs.

SKYR

Although marketed as a yoghurt, this Icelandic product is technically a soft cheese made from considerably more milk — it takes 3.5 litres of milk to make 1 litre of skyr, roughly four times the amount needed to make regular yoghurt, and because of this it contains about twice as much protein. Whey is removed by ultra-filtration to make it thick. A culture of lactic acid bacteria is added and the final product is similar in texture to Greek yoghurt.

NON-DAIRY

The market for non-dairy yoghurts has skyrocketed and includes soya, almond, coconut, oat, rice, hazelnut and hemp. All tend to be lower in calcium than regular yoghurt. They also lack iodine and a study at the University of Surrey linked the dairy-free yoghurt fad to a rise in the risk of deficiency of the trace mineral that’s needed for healthy thyroid function and fertility. Two small cartons of yoghurt a day is enough to meet the 150mcg iodine needs of adults, but dairy-free versions usually contain negligible amounts. They can also be high in sugar — the BMJ study found that non-dairy yoghurts contained an average 9.2g sugar per 100g. On the plus side, most are suitable for people with lactose intolerances.

The Times