Until late 2024 I’d never heard of spelt, an ancient relative of wheat. It largely disappeared from European diets during the 19th century because it was considered inefficient to farm, and while it’s reappeared on the shelves of Waitrose more recently, I never paid it much attention. I certainly didn’t expect spelt to become a cornerstone of my diet, consumed each morning with chia seeds, blueberries, hazelnuts and a dash of milk.
My discovery of spelt, which is renowned within nutrition circles for being particularly rich in fibre and various vitamins and minerals, was part of an investigation I undertook over the past two years into the science of how our diet affects how well we age.
As a neuroscientist, I’ve long been intrigued by our growing understanding of the biology of ageing, a field known as geroscience. I was already aware of the negative impact that food could have. For example, there is a growing body of research to suggest that an excess of calories, and in particular saturated fat, can drive premature puberty, which is recognised as a sign that the body’s biological clock is moving too quickly.
Diet can also drive visible signs of ageing. Scientists have discovered that too much sugar causes chemical reactions in the blood that stiffen the collagen in our skin, triggering the formation of wrinkles, and even crystallising proteins in our eye lens, leading to cataracts. But what about the benefits of the right foods? I decided to try out two different longevity diets, with the aim of revamping everything from my immune health to the stress being inflicted on different organs.
Low-calorie, nutrient-dense
The first diet was inspired by a strange experiment from the early Nineties in which eight middle-aged volunteers were locked up for two years in a vast complex of glass domes and pyramids in the middle of the Arizona desert — an artificial “mini Earth” with miniature rainforests and even a living coral reef. The idea was to see whether they could live off the land, something that would be necessary for human colonies on other planets.
The primary aim of Biosphere 2, as the experiment was known, was something of a flop. Oxygen levels failed and had to be pumped in, and while the inhabitants managed to grow food, they struggled to grow enough. As a result, they were restricted to about 1,800-2,000 calories a day of only organic vegetables, eggs, fish, goat’s milk and occasionally lean meat, a low-calorie but nutrient-dense diet.
At the end of the experiment, tests on some of the volunteers revealed extraordinary changes in their biology. Their blood pressure, insulin sensitivity, blood sugar control, cholesterol and levels of inflammation had all markedly improved. Underlying health issues had been resolved. It turns out that eating slightly less, but increasing the quality of the food, is a more potent way of slowing ageing than any drug. So for two months I tried to do the same, limiting myself to a strict 2,100 calories per day, a significant drop from my typical 2,700.
I excluded all highly processed foods, refined carbohydrates and sugar, and focused on nutrient-dense alternatives. Spelt was in, as were nuts, seeds and dried fruit for snacks, lean meats such as chicken and lamb, slow-cooked dinners and broths. My partner and I became particularly fond of making Vietnamese pho, featuring chicken, beansprouts and ample herbs. I usually consume alcohol moderately, maybe a glass of wine on Fridays, so I didn’t make any changes there, but I did start drinking two or three daily cups of green tea, a beverage packed with flavonoids. These plant chemicals have been shown to be particularly good at helping the body to shed damaging internal or visceral fat, as well as toning the health of blood vessels, making us more resilient to hypertension.
It wasn’t easy to begin with. For a week I was plagued by sugar cravings and the persistent sensation of a hole in my stomach, but within a fortnight it had become more or less routine. By the end of the two-month experiment, I felt better: I had more energy, was better equipped to cope with stress, and felt mentally sharper. While I’d shed 6kg (nearly a stone) and felt noticeably trimmer, the most significant changes were internal.
Before and after the diet I visited the University of Birmingham, where tests showed that my levels of inflammation and visceral fat had plummeted. I took a blood test that measured 12 metrics of immune health, ranging from the number of new white blood cells being generated to the number of inflammation-suppressing cells. The results revealed that my “immune age” had reversed by approximately two years.
David McHugh/Brighton PicturesUltra-high fibre
For the second diet, I wanted to move away from limiting calories, and focus instead on eating more of the right foods. Epidemiologists have long been aware of the healing powers of fibre. It is metabolised into a range of chemicals called short-chain fatty acids, which carry out remarkably diverse roles when it comes to tuning the immune system, resolving inflammation in the gut and causing cancer cells to self-destruct.
High-fibre foods tend to be particularly rich in micronutrients such as B vitamins, zinc, iron, selenium and magnesium, which are all crucial for maintaining immune systems and brain health. People who consume lots of fibre (think 40-50g — 1.5 to nearly 2oz — a day) have much lower rates of colorectal cancer and inflammatory diseases, and upping your fibre intake can even benefit cognition. In a clinical trial in 2024 that placed 51 men and women with mild cognitive impairment on a high-fibre diet for 20 weeks, 71 per cent of them showed improvements in cognitive function.
The problem is, the average British person doesn’t come close to eating even 20g a day (the NHS recommends 30g). While a slice of white bread contains 0.7g of fibre, one cup of lentils, for example, contains as much as 18g. Two tablespoons of chia seeds provide 10g of fibre.
I set out to increase my fibre intake to 50g a day, which I achieved through whole grains such as spelt, but also brown rice, quinoa and oats, and in particular, more portions of legumes such as beans and lentils. I started adding a portion of chickpeas to most meals. Fibre is highly satiating, meaning that the more you have, the less inclined you are to seek out snacks between meals.
Like all dietary changes, there are some adjustments to expect. More fibre means more bowel movements, which is a good thing as it clears toxins from the gut. The Irish surgeon Denis Burkitt is known for making the link between “small stools [and] large hospitals”, and you might feel a little gurgly for a few days as your gut copes with having to work a little harder. But based on my experience, it’s an effective way of improving how you age. Over the course of five months, my rate of ageing slowed by 16 per cent, according to tests measuring patterns of ageing in my DNA, while other tests began to indicate that my biological age was now slightly younger than my chronological age.
Geroscience is a fast-moving field and insights are emerging all the time. One particularly compelling discovery in the past ten years has been the revelation that the plant chemical astaxanthin, which you can add to your diet by consuming dried seaweed, for example, can activate a particular gene that ramps up your body’s ability to repair itself.
The key thing is that research shows that whatever age you are, it’s always possible to make changes to your diet which can noticeably improve your health — and the changes don’t need to be extreme.
Having seen the benefits of dietary change, I’m attempting to consume 40g of fibre daily as well as an omega-3 supplement, another key intervention which is thought to strengthen muscle, immune, brain and heart health. While my weekly shop does cost slightly more than it used to, I’m spending less money on snack foods — and if all it takes to slow the clock and give me some better quality years is eating more carefully, it feels like a payoff that’s going to be well worth it.
The Age Code: The New Science of Food and How It Can Save Us by David Cox is published by Fourth Estate. Order your copy at Times Bookshop
