As people around the world live longer and longer, staying healthy into old age has never been more important. Scientists agree that sticking to a balanced diet in midlife is essential if you want to remain fighting fit as you age.

A recent study published in the journal Nature Medicine found people who followed the Alternative Healthy Eating Index (AHEI) were more likely to achieve healthy aging than those eating any other diet. This diet is rich in fruits, vegetables, plant proteins, whole grains, nuts, legumes, and lower-fat dairy products, and includes moderate amounts of fish.

“These eating patterns are rich in whole foods, healthy fats, and lean protein, all of which have been shown to reduce the risk for chronic diseases and promote brain health,” Shelley Balls, a registered dietitian and nutritionist, told The i Paper.

Eat plenty of protein

Protein is a key food group that can improve healthy aging, as it helps counteract many of the natural changes your body goes through as you get older. As we age, we naturally lose muscle mass, which can lead to weakness and a higher risk of falls and fractures.

“Adequate protein intake can help maintain muscle mass to promote strength and prevent falls,” says Balls.

Protein is also essential for healing wounds and injuries, recovering from illness or surgery, and maintaining skin elasticity.

NHS guidelines recommend around 0.75g to 0.8g per kilogramme of bodyweight per day – that’s around 64g a day for an average man, or 55g for a woman.

This is the equivalent to eating 40g of oats (5g of protein) one 100g greek yoghurt (10g), two medium eggs (12g), two slices of wholewheat toast (8g) and one chicken breast (30g) – this totals 65g protein.

Other foods rich in protein include lean meats, fish, seafood, cheese, Greek yogurt, lentils, chickpeas, beans, tofu, quinoa, nuts, and soy milk.

“Beyond the age of 60 to 65, you might need to increase your protein intake,” says Dr Collins,  associate professor of nutrition at the University of Surrey. “There’s only so much you can cope with though, because sometimes you’ve got gastric insufficiency where you can’t eat 100 grams of protein in one sitting.” In all cases, they recommend eating a bit more protein throughout the day in smaller increments, but this must, again, be coupled with physical activity.

Make sure your diet is rich in antioxidants

Many plant-based foods are rich in antioxidants, which protect your body’s cells from damage caused by molecules called free radicals.

“On a cellular level, ageing is the slow breakdown of healthy cells caused by free radicals, the unstable molecules generated every time we breathe, eat, or produce energy. Over time, these molecules damage cells, impair DNA, and erode the structures that keep us young and healthy,” says Dr. Hamid Djalilian, a professor of otolaryngology [head and neck] at the University of California.

“Antioxidants (from fresh foods like fruits, vegetables, herbs, legumes, whole grains) protect us from oxygen free radicals.”

Foods rich in antioxidants include beans, berries, apples, pecans, plums, cherries, kale, spinach, nuts, seeds, and spices like turmeric, ginger, cinnamon, and cloves.

“There’s no official ‘daily requirement’ but research suggests aiming for 6–10 servings of antioxidant-rich plant foods daily,” says Trista Best, a registered dietitian and adjunct nutrition professor. “Aim for at least 2–3 servings of deeply colored fruits and 3–5 servings of vegetables daily.”

One handful of blueberries (half a cup) is considered a single serving, as is half a cup of cooked kale, spinach, or broccoli.

“A smoothie with berries and leafy greens and matcha is an antioxidant powerhouse,” says Best.

Eat the right kind of fats – in moderation

There are several types of fat in our food, and some are a lot better for our health than others. Fats considered to be healthy include monounsaturated fats and polyunsaturated fats, which are found in foods like avocados, nuts, seeds, olive oil, and fatty fish.

Healthy fats like omega-3 fatty acids are essential for brain structure and function, and help slow cognitive decline, while other types of healthy fat are crucial for the absorption of vitamins, the manufacturing of hormones, and managing cholesterol levels.

“Good fats are unsaturated fats such as olive oil, nuts, seeds, and fish. They strengthen cells, calm inflammation, and support the body’s natural repair systems,” says Djalilian.

Some fats, such as trans fats and saturated fats, are less healthy. These fats, which are found in processed meat like bacon and sausages, hard cheeses, whole milk, baked goods, and fried foods, increase LDL (bad) cholesterol and decrease HDL (good) cholesterol, which increases your risk of cardiovascular disease.

“Adequate intake of healthy fats found in fatty fish, nuts and seeds can promote brain health, which is something you don’t want to take lightly while ageing. In fact, switching out solid fats such as butter and other solid fats for unsaturated fats has been shown to decrease the risk for chronic disease,” says Balls.

Around 20-35 per cent of daily calories from healthy unsaturated fats like monounsaturated and polyunsaturated fats. You can supplement your fat intake by adding high-fat foods to your meals, such as a handful of walnuts and an olive oil dressing added to a salad, or avocado and salmon added to your eggs on toast.

“For someone who needs 2,000 calories per day, that’s 44-77 grams per day, equivalent to one tablespoon extra virgin olive oil, half an avocado, one ounce of walnuts, and four ounces of salmon,” Balls said.

Get all your vitamins and minerals, especially vitamin D and calcium

Vitamin D and calcium are important for ageing well, as they support key body systems that start to wear down with age. Calcium helps maintain bone strength, while vitamin D helps your body absorb this calcium (helping to reduce the risk of osteoporosis and fractures), plays a role in cognitive function and immune health, and is linked to lower risks of heart disease and type 2 diabetes.

“A balanced diet should also include an abundance of calcium and vitamin D to help keep bones healthy as you age. A calcium and vitamin D supplement may be needed based on dietary intake and climate,” says Balls.

Oily fish (such as salmon, sardines, and tuna), red meat, liver, and egg yolks are naturally rich in vitamin D, as well as foods fortified with vitamin D like dairy products and breakfast cereals.

Adults need 10 micrograms of vitamin D a day, which can be achieved by eating one portion of oily fish, as they generally contain 12-13 micrograms per portion. Alternatively, two eggs contain 3.3 micrograms of vitamin D, one glass of fortified soya milk contains 1.6 micrograms, and a grilled pork chop contains 0.6 micrograms, so you can pick and choose how to build up your vitamin D intake throughout the day.

Berries fight age-related mental decline

Along with being rich in antioxidants like anthocyanins, flavonoids, and vitamin C, berries — especially blueberries, strawberries, blackberries, and raspberries — have also been found to help lower blood pressure, reduce cholesterol levels, improve cognitive function, and delay age-related mental decline.

“Berries have also been shown to promote brain health and are also a great source of dietary fiber to promote gut health.” says Balls.

About half a cup of blueberries, raspberries or blackberries is a single serving, as is 8-10 strawberries.

“Half to 1 cup daily (or at least 3–5 servings per week) is linked to cognitive and cardiovascular benefits in midlife,” Best says. “Toss into yogurt, oatmeal, or snack on frozen berries mid-afternoon.”

Avoid cakes, cookies, and crisps

The Nature Medicine study additionally found that a diet composed largely of trans fats, sodium, sugary drinks, red meat, and processed meat, detracted from ageing healthily.

“As you age, one food that you want to eat less of are simple carbohydrates, which include added sugars. Overconsumption of simple carbohydrates can increase your risk of dementia, type 2 diabetes and heart disease,” Balls says. “Sodium is also a big one that can quickly add up in your diet, and over time lead to increased risk for hypertension, and can lead to more serious heart events.”

Avoiding foods high in sugar and trans fats, such as cookies, cakes, crisps, and fried foods is best for ageing healthily.

“If you had to pick one food item to avoid in midlife, it would be trans fats. In the recent Nature study, trans fats topped the list in badness, negatively impacting every domain of ageing. You’ll find them in margarine, processed snacks, and fried fast food,” Djalilian says.