Nutrition expert Professor Tim Spector has stressed the crucial role of diet in protecting the body from viruses and reducing the risk of severe illness, including long Covid. The King’s College London genetic epidemiologist and founder of the Zoe health app explained that gut health plays a key role in shaping the body’s immune response and preventing dangerous inflammation.
Spector highlighted that most of the immune system resides in the gut, where it receives vital signals from microbes that help it respond appropriately to infections. “We now know that most of our immune system is in our gut, and the way it gets its signals, and it understands what’s going on around it, is through the gut. Microbes are healthier in your gut microbes,” he said, reports in the Mirror.
He added, “The more diverse they are, the better you’re going to be able to control your immune system. And this means it’s going to react appropriately to, say, a COVID-19 virus. It’s going to try and kill it, but without overreacting and killing you.”
Spector warned that eating processed and unhealthy foods can cause inflammation, weakening the body’s ability to fight real infections. “People eating junk food are going to have an inflamed gut microbiome that’s trying to put out fires all over the place. And so when a real virus comes along, it’s not able to pin it down,” he said.
To build strong immunity, Spector recommends focusing on a diverse plant-based diet, fermented foods, and high fiber intake while avoiding ultra-processed products. “If you want to have the best immune system, you need to make sure your gut health is in the best possible way. I can’t stress enough. It’s plant diversity, it’s fermented foods, and it also means not having ultra-processed foods and getting plenty of fiber in there,” he said.
Spector cautioned that pandemics are likely to become more frequent and severe, urging people to rethink their diets now. He also criticized Britain’s reliance on ultra-processed foods, noting that the country “leads Europe in ultra-processed food consumption, with a staggering 57% of our daily food intake coming from these products.”
He described such foods as “edible food-like substances” that are stripped of nutrients and filled with chemicals and additives. “They take the essential extracts from food and they combine them in different ways,” he explained. “They have to add glues, chemicals, and additives to stick stuff together and to make it look like food again.”
Spector advises people to eat at least 30 different plant varieties per week and to include fermented foods such as kefir and live yogurt. “They seem to support your immune system, which is so vital to fighting allergies, infections, cancer, and ageing,” he said.
He cited a U.S. clinical study showing that people who ate four to five servings of fermented food daily improved immune function and reduced inflammation within two weeks. “So, if you have one or two portions daily, you will likely also benefit,” he concluded.