Eating quality carbohydrates has been linked to better health later in life. Photo / 123rf
New research shows the optimum diet for healthy ageing involves a variety of fibre-rich carbohydrates.
It’s a rule all too familiar to every dieter: to lose weight, then stay slim and healthy, shunning carbohydrates is non-negotiable. Cutting out the likes of bread, pasta and potatoes has been a mainstay of weight-loss regimes since the early 2000s, and the low-carb trend shows no signs of abating.
But, as a new study shows, not only do carbohydrates provide the body with a source of energy that is vital for our brain, muscles and all other tissues to function properly, they also hold the key to healthy ageing – depending on the type we choose.
The research, by scientists at Tufts and Harvard universities in the US, analysed the diets of more than 47,000 women and found that eating certain types of “quality” carbohydrates was linked to significantly better health in older age. The women who ate the healthiest carbs were most likely to avoid any major illness by age 70, including heart disease and cognitive decline.
“Carbs are not only where we get our energy source, but they also give us vast quantities of nutrients, including fibre, phytochemicals, vitamins and minerals,” says Laura Southern, a nutritionist and founder of London Food Therapy. “They are vital to help us thrive as we age – but in terms of their health benefits, some offer far more than others.”
Carbohydrates are one of three macronutrients, with protein and fat, and current dietary guidelines recommend that 45% to 65% of our daily calories should come from them. But which kind are best for us?
The new research found that eating carbs from wholegrains, fruits, vegetables and legumes in midlife was linked to a 6 to 37% greater likelihood of healthier ageing. These are the “quality” carbs we should be prioritising in our diet.
“Quality carbs are those which are minimally processed, ideally whole foods, which means their nutrients haven’t been stripped away by manufacturing,” says Southern. “They contain fibre, which means they take much longer for our bodies to digest, keeping our blood sugar levels steady and keeping us full longer.”
Conversely, carbohydrates from added sugars, refined grains, potatoes and starchy vegetables were linked with 13% lower odds of healthy ageing.
“With white or refined carbs, such as white bread, pasta and rice, most of their nutrients and fibre have been lost, so our bodies don’t have to work hard to break them down,” says Southern. “This means they give us a very high blood sugar spike.”
Added sugars and starchy vegetables such as potatoes, corn and squash have a similar effect on our blood sugar, and over time, these spikes can cause chronic inflammation, leading to problems including obesity, heart disease, stroke and Type 2 diabetes.
One of the main benefits of quality carbs is the fibre they contain, which has “far reaching beneficial effects beyond gut health, including brain and metabolic health”, according to Dr Sammie Gill, registered dietitian and spokesman for the British Dietetic Association.
A landmark study that included 185 observational studies and 58 clinical trials showed that a fibre-rich diet reduces the risk of heart disease, stroke, Type 2 diabetes and colon cancer by 16-24%.
If ageing is characterised by inflammation, “fibre counteracts pro-inflammatory processes because of its anti-inflammatory effects”, explains Gill.
One way it does this is through the gut microbiome. Fermentable fibres such as prebiotics – including apples, berries and oats – feed our good bacteria, and in return, they release beneficial compounds into the gut, including short-chain fatty acids (SCFAs). “Studies have shown that SCFAs can regulate production of pro-inflammatory compounds, such as cytokines,” says Gill.
Southern says that this is why low-carb diets such as Atkins, keto and carnivore are not healthy. “Fibre is lacking in the British diet as it is, and fibre is essential for long-term health,” she says. “We really don’t want to lose any more.”
Quality carbs are also rich in phytochemicals, beneficial chemicals produced by plants. “These can also dampen inflammation by acting as free radical scavengers and protecting cells from damage,” says Gill.
Although very low-carb diets can certainly work in the short term, not only do they tend to prove unsustainable – you’ll regain the weight as soon as you reintroduce the carbs – but they are also unnecessary.
A comprehensive analysis published in the British Journal of Nutrition reviewed randomised controlled trials comparing low-carb and low-fat diets. The findings revealed that while low-carb diets led to modestly greater short-term weight loss, the differences were minimal and not clinically significant. The long-term effects on weight maintenance were similar between the two types of diet.
Other studies have suggested the keto diet, which restricts carbohydrates to 20-50g per day with the aim of inducing ketosis, in which the body primarily burns fat for energy rather than carbs, could have serious health drawbacks. Not only did keto dieters in one study see their daily fibre intake fall to around 15g per day – half the amount recommended by the NHS – but they had reduced levels of the gut bacteria bifidobacterium, associated with strong immunity.
Instead, experts recommend aiming for a diet that’s as varied as possible. “Low-carb diets are notoriously difficult to stick to,” says Southern. “If you want to lose weight healthily, eating quality carbs will ensure you’re getting the nutrients you need, keep you feeling full and give you plenty of energy.”
When it comes to carbs, it’s the quality and quantity you need to keep an eye on.
Fruit and vegetables
When choosing fruit and vegetables, variety is key, says Southern, as is ensuring we get a spectrum of different colours. “The polyphenols which give plants their pigmentation also give us the nutrients to reduce inflammation and chronic disease, so we want to consider how many colours we’ve had across a week,” she says.
And although all fruit and vegetables provide us with vitamins, minerals and fibre, some are naturally higher in sugar or starch, which causes the rises in our blood sugar.
She recommends prioritising lower-sugar choices. “For fruit, this is produce which grows in the UK: orchard fruit such as apples and pears, as well as cherries and berries,” she says. Sweeter tropical fruit such as mangoes, bananas and pineapples should be eaten less often.
Likewise, overeating starchier vegetables including sweet potatoes, squash and corn can mean consuming too many calories and could potentially impact blood sugar levels. Instead, load up on leafy greens, cruciferous vegetables such as broccoli and cabbage, alliums such as leeks and onions and other non-starchy options including asparagus, carrots, peppers, tomatoes, aubergines and courgettes – all of which are lower in carbohydrates and contain more fibre.
Legumes
“Legumes, including beans, peas, chickpeas, lentils and peanuts, are one of the best groups of foods we can eat for our health,” says Southern. “If you look at the Blue Zones – the places in the world where people live longest – legumes feature in high levels in every diet.”
They have a host of benefits, with one major systematic review of 32 studies showing that higher legume intake was associated with a 6% reduction in the risk of death from all causes, and a 9% reduction in the risk of death from stroke.
“They’re very rich in fibre, which is excellent for gut health and helps us feel full,” says Southern. “They contain protein, which slows the release of the carbohydrates, as well as iron and potassium. They’re also highly anti-inflammatory.”
Although legumes are starchy, they are high in resistant starch, a type which is not fully digested in the small intestine and doesn’t cause the blood sugar spikes of other high-starch foods.
Southern suggests adding legumes into meals wherever possible. “Throw a packet of lentils into a bolognaise, add beans to pasta dishes or roast chickpeas in oil and salt to eat as a snack instead of crisps,” she says.
Wholegrains
Delicious as white bread, rice, pasta and buttery pastries are, they’re among the worst culprits for sending blood sugar levels sky-high. They’re also low in nutrients, often highly processed and, in the case of pastries, cakes and other white carb-based confectionery, packed with sugar, fat and calories.
“Refining means the removal of the fibre-rich outer layer, called the bran, and the nutrient-packed core of the grain, called the germ,” says Gill. “Wholegrains contain around 75% more nutrients compared with refined grains.”
Replacing white rice with the brown or wild version boosts its health benefits significantly; a bowl of steel-cut porridge oats is a far better breakfast option than cereal; and a microwaveable packet of ancient grains such as spelt, buckwheat and quinoa makes a quick, tasty and healthy substitute for pasta. “Quinoa is always my number one choice, because of its protein content,” says Southern.
If you really can’t let go of white pasta, “pair it with protein from meat, fish or beans, and some good fat from olive oil, to slow down its impact on your blood sugar, and eat it with some vegetables or a big salad to reduce the portion size”, she says.
According to market research agency Mintel, 62% of shoppers still buy sliced white bread, despite it containing very little in the way of nutrients. Southern recommends quitting the white bread habit and looking for a loaf with a higher fibre content. “One with added seeds or different grains, such as rye, will make you far less likely to experience an energy slump and eat a chocolate bar mid-morning,” she says. “They’ll also be far better for your health in the long term.”
Protesters chanted 'Bezos, out of the lagoon' in Venice's city centre.