Harvard doctor who has studied the gut for over 10 years reveals the foods he avoids - and what to eat instead

Daily Mail​

20-07-2025

A leading gut expert has revealed a surprising list of seemingly healthy foods that he avoids to protect his gut health and ward off inflammation.
Dr Saurabh Sethi, a Harvard trained gastroenterologist, has warned that people are consuming 'hidden' ultra-processed foods, preservatives and sweeteners.
From snack bars to salad dressings, Dr Sethi—who has 1.2million Instagram followers—says that people are still being duped by products that appear to be healthy options but perhaps aren't.
Among the worst offenders, he says, are granola, fruit yoghurts and sugar-free chewing gum—all of which are often marketed as healthy options but may in fact contribute to inflammation and poor gut health.
Snack bars also make his blacklist. 'They're basically candy bars in disguise loaded with emulsifiers, fake fiber and seed oils,' he said in an Instagram post.
Emulsifiers, commonly used to bulk out and preserve processed foods such as yoghurts and breakfast cereals, can alter the structure of the gut lining.
According to Dr Sethi, when these additives are ingested, they form a gel-like clump that may interfere with digestion and disrupt the balance of microbes in the gut.
This, it has been theorised, can interfere with the natural separation between the fatty layer and the water layer in the gut, increasing the risk of bacterial infections.
Cereal bars may seem like a convenient way to manage hunger on the go, but Dr Sethi warns they are also full of additives and seed oils
Instead of reaching for a convenient but highly-processed snack bar, Dr Sethi opts for a handful of nuts or fruit with nut butter.
Nuts are naturally high in fibre—which is associated with a lower risk of heart disease, stroke, type two diabetes and bowel cancer—as well as protein and omega-3 fats.
Commonly referred to as roughage, fibre also helps prevent constipation, aiding digestion and helping us feel fuller for longer.
Flavoured yoghurts which appear healthy are just as bad according to the gastroenterologist who said they are often packed with added sugars—above the natural content of a food or drink item—and artificial flavourings.
And he didn't stop there when it comes to breakfast staples with hidden ingredients. 'Granola with added sugars are often worse than desert,' he said.
Instead he recommends starting the day with a bowl of porridge oats or plain yoghurt with berries and chia seeds.
Berries, such as blueberries and chia seeds are packed full of antioxidants which can help the body fight off free radicals which have been linked to diseases like diabetes and cancer.
It is not just your breakfast that is likely to be packed full of additives—snacks and condiments that are marketed as 'sugar free' or 'healthy' are also worth being wary of Dr Sethi said.
'Sugar free gum contains artificial sweeteners like sorbitol which can trigger gas, bloating and diarrhoea.'
Instead Dr Sethi recommends chewing fennel seeds—which are naturally high in iron, zinc and calcium—after a meal to aid digestion and freshen breath.
Also on the list to be avoided is pre-prepared salad dressings. 'Even "healthy" store-bought salad dressing are often full of inflammatory oils and added sugars,' he said.
'It is better to make one fresh yourself from olive oil, lemon, mustard and herbs.'
Any refined seed oils such as canola, soy or corn oil are also a red-flag for Dr Sethi as they are high omega-6 fats.
Some claim these could be just as bad, or even worse for the heart as traditional animal fats like butter and beef dripping.
'Try cooking with avocado oil, extra virgin olive oil, ghee or coconut oil to keep your gut lining healthy and ward off inflammation', the gut expert recommended.
Dr Sethi also recommends reducing the amount of milk—and, therefor the milk sugar lactose, which can can digestive issues in those who have intolerances—consumed.
'Lactose can be irritating for sensitive guts and trigger bloating or discomfort,' he explained. 'Instead try plain coffee or add cinnamon and almond milk.'
Finally, Dr Sethi warned instant noodles can wreak havoc on your gut health.
He said: 'Instant noodles are high in preservatives, low in nutrition and terrible for gut microbes. For a 10 minute upgrade pour broth over rice noodles and veggies.'
The gut expert's warning comes as concerning new research has found that children who consume a diet packed with sweeteners may be at higher risk of reaching puberty earlier.
Commonly-used sweeteners found in drinks like Diet Coke and chewing cum as sugar alternatives have long been linked to certain cancers and heart issues.
But now, Taiwanese experts have found that high levels of the additives could also trigger central precocious puberty—where the first signs of puberty typically emerge before the age of eight in girls and nine in boys.
Higher consumption of 'added sugars' has also been linked with an earlier puberty increase the risk of other health conditions including depression, diabetes and even cancer.