Health: How a carefully balanced diet lets immune system thrive under pressure

It’s a necessary evil with which every human body must contend. Yet little is really known about how to control the impact of inflammation.

By signalling the immune system to heal and repair damaged tissue, it protects us from harm but it’s also a key factor in countless diseases, including Covid-19.

Now, in a new book, biochemist Dr Barry Sears outlines how diet can be a powerful tool in maintaining such a delicate balancing act. By eating the right mix of protein, fat, carbohydrates and vitamins, genes that cause inflammation can be “silenced” and genes that reduce it can be “switched on”, leading to better health.

Dr Sears, who researches the hormonal effects of food at the Inflammation Research Foundation in the US, says: “Inflammation is like the weather. We talk a lot about it, yet we know little about how to control it.

“You need to turn on inflammation to protect your body from infections and injuries, but also need to turn off inflammation, so it doesn’t continue to attack your body.”

There is no drug to maintain this balancing act, but your diet can, if you treat it like a “super-drug”.

“There’s no magic bullet in nutrition, only the constant orchestration of the hormones and genes that reduce, resolve and repair the damage caused by inflammation,” says the food researcher.

While Dr Sears says it can be beneficial for many things – including pregnancy health, athletic performance and fighting off illness – some experts say the notion of an “anti-inflammatory diet” can be misleading, and striving for a healthy balance is better than following regimented diet plans.

“We know chronic inflammation can play a role in ill health and that it can be affected by many factors, including the diet, obesity, diabetes, high blood pressure and smoking,” says Sarah Coe, a nutrition scientist with the British Nutrition Foundation. “But, as yet, there is a lack of scientific evidence to support an ‘anti-inflammatory’ diet, so we need a better understanding of the relationship between the foods we eat and inflammation.

“Diets that have been claimed to be ‘anti-inflammatory’ tend to be a Mediterranean-style diet or diets rich in particular nutrients (eg vitamins A, C and E, selenium, zinc and omega 3s), which we can get from eating a healthy, balanced diet.

“While the evidence isn’t there to recommend a specific diet, having a generally healthy diet and lifestyle may help to reduce levels of chronic inflammation, as well as having other benefits for health.”

So how should we be eating? Here are Dr Barry Sears’s five dietary strategies…

Gene genius

Polyphenols are the chemicals that provide vegetables and fruits with their colouring, and Dr Sears says they also activate the genes that repair tissue damage caused by inflammation. You’ll generally need to consume about 10 servings of non-starchy vegetables and fruits per day to get adequate levels of polyphenols, he says. “This is why it’s challenging to consume all the food you need, even though you’re restricting calories,” says Sears, who suggests the “ABCs” and berries are among the best sources.

Watch the calories

Counting calories is not the be all and end all of maintaining a healthy weight. However, Dr Sears says it’s important to be aware of them. “The most proven method to live longer with less chronic disease is to restrict calories without malnutrition,” he says. “Those calories have to be balanced in protein, carbohydrate and fat to generate the correct levels of hormones needed to reduce inflammation as well as prevent hunger and fatigue.” This doesn’t necessarily mean feeling deprived of food, though – for example, Zone meals can contain 400 calories each, yet quite a lot of volume if you have the balance of veg right. So some people may even find consuming enough food every day is actually quite tricky.

Gut instincts

A primary source of diet-induced inflammation comes from a leaky gut. “Your best defence is consuming adequate levels of fermentable fibre to produce metabolites in the gut that also reduce inflammation,” explains Dr Sears. This means at least 30g of fibre per day from non-starchy veg (primarily the ABCs: artichokes, asparagus, broccoli, cauliflower and spinach) and limited amounts of fruits (ideally berries) for good gut health.

Get the balance right

“Your diet can either cause inflammation or reduce it,” says Dr Sears, who recommends the Zone Diet. “It’s a highly-personalised plan but the premise is to eat the right balance of low-fat protein and carbohydrate (such as non-starchy veg), plus a little fruit and monounsaturated fat at every meal.” Most females, he says, need 90g of low-fat protein per meal, while males need 120g. A typical Zone meal might consist of a 120g portion of chicken, fish or a plant-based meat substitute for vegans, three servings of non-starchy vegetables, a small serving of berries for dessert, and 10ml of olive oil for fat.

Essential acids

Omega-3 fatty acids are building blocks for the hormones that turn off inflammation, says Sears, who explains you need to eat at least 3g of good omega-3 sources per day to make enough of these hormones. The average Brit only consumes 150mg of omega-3 fatty acids a day, so many of us might not be getting quite enough. Oily fish, nuts and seeds are good sources. “If you can’t turn off inflammation, it’s unlikely you can repair the tissue damage caused by that inflammation,” says Sears, who points out that unless you’re eating enough fatty fish regularly, you may need to take omega-3 supplements.