Eat more protein: the new way to improve your brain function

A keto diet can help with everything from dementia to depression, according to nutrition expert Dr Georgia Ede. She tells Peta Bee why.

It’s best known as a slightly faddy route to weight loss, but could the ketogenic (keto) diet, high in proteins and fats and low in carbs, be the key to preserving brain health as we age?

It’s a proposition being tested by scientists and is the subject of a book, Change Your Diet, Change Your Mind, by Dr Georgia Ede, a Harvard-trained psychiatrist and nutrition expert.

The keto diet is one that contains minimal carbs, a moderate but not excessive amount of protein and is relatively high in fat. Its name comes from the “ketogenic” effect it has on the body, similar to that of long-term fasting, causing the breakdown of fat into molecules called ketones that become a source of energy for cells.

Although its connection to brain health is a new area of investigation, the diet was originally designed in the 1920s to reduce and control seizures in people with epilepsy and is still sometimes used for this reason.

As a result of studies showing it can help to reduce depression, including a 2024 paper in the Frontiers in Nutrition journal, it is gaining a following among those seeking control over their mood swings and anxiety.

There are also signs that it could play a role in reducing the risk of dementia.

“The keto diet has many health benefits, but three main ones for the brain,” Ede says.

First, by reducing and stabilising brain glucose levels it could help to dampen down the inflammation related to the development of dementia.

“When glucose levels are running too high in the brain, it triggers a wave of damaging inflammation and oxidative stress,” Ede says.

“These are two of the main causes of most chronic disease in the brain and body.”

Switching to a keto diet might also help to lower insulin, the hormone that regulates sugar levels in the blood.

Could a keto diet be key to brain health?

“If insulin levels are too high, the brain can become insulin-resistant and that makes it increasingly difficult for insulin to cross into the brain where it is used to turn glucose into energy,” she says.

“Keeping insulin levels within a healthy range protects the brain’s precious energy production systems.”

Finally, it produces ketones, acids made when the body uses fat instead of glucose for energy. “They are little fragments of ready-to-burn fat that can cross into the brain and be used for energy,” Ede says. “Those energised brain cells will stabilise brain chemistry and promote brain healing.”

For a small study in Alzheimer’s Research & Therapy journal, a team of New Zealand-based researchers asked people diagnosed with Alzheimer’s to follow a keto diet for 12 weeks, their own diet for 10 weeks and then to adopt a low-fat diet for 12 weeks.

Results showed that on the keto diet, the patients reported better quality of life and daily functioning, but although thinking skills improved they were not significantly better than on the other diets.

However, another earlier study in Nutrition & Metabolism journal suggested that Alzheimer’s patients prescribed a ketone-raising drug performed better on cognitive tests than those taking a placebo medication.

So what should we be eating? Ede claims it doesn’t have to be complicated – most of us need no more than three meals a day.

She says each could contain predominantly fats and protein.

“The simpler the better is the message,” she says. While she believes that a keto diet is for life, many of her followers, especially in America, have adapted it and use it as a jump start to reset their diets for a few weeks, or practise keto-cycling, which is typically five days on, two days off.

The keto diet is known for its lack of fibre and minimal plant foods.

Many would question how healthy a diet can be without these – but Ede is adamant that it can be nutritious.

“It is a wholefoods diet that contains high-quality proteins such as meat, seafood, poultry and eggs – or tofu for those on a vegan diet,” she says.

“And it also contains unprocessed fats from whole plant and animal foods.” Nor is it completely carb-free.

“Some low-carb plant foods, including vegetables and fruit, can be incorporated,” Ede says.

She recommends up to 50g of carbohydrates a day for most people – low-starch vegetables and fruits are the main sources and the carbs should be spread across your two to three daily meals.

For example, a 100g serving of cauliflower, cabbage or cucumber provides 3g of carbs; 100g of Swiss chard, spinach, or celery provides 2g; 100g of brussels sprouts or green beans provides 5g.

You can still eat vegies like cauliflower and cucumbers.

She argues that you wouldn’t feel hungry without bread, potatoes and rice.

“Protein foods are far more satiating than carbohydrates and one of the big surprises when people switch to the keto diet is that they say they feel less hungry,” Ede says.

“Most find that eating protein, such as eggs, for breakfast means they don’t get hunger pangs before their next meal and some find they naturally reduce their main daily meals from three to two.”

She adds: “My own mother had a lot of mental and physical health problems 18 months ago, but she switched to a ketogenic diet and now, aged 91, she has lost almost 60lb in weight and her health problems have been reversed.” Here’s how Ede suggests we do it:

Cut back on sugar

The brain does need some glucose at all times to function at its best, but Ede says that glucose does not need to come from dietary carbohydrates. “Our bodies can safely and reliably make all the glucose we need from protein and fat through a process called gluconeogenesis.”

It’s recommended to cut back on sugar.

In fact, she says, carbohydrates are the only macronutrient that is optional for brain health. “Paradoxically, the more sugar you eat, the more insulin-resistant the body becomes and the harder it is for your brain to turn that sugar into energy,” she says.

Focus on protein and fats at every meal

Ede claims that meat is an important component of a brain-friendly diet. “It doesn’t have to be red meat, but centring your meals around a good-sized portion of meat, poultry or fatty fish is ideal,” she says.

“Dark meat, such as duck and poultry legs and drumsticks, and chicken or turkey are all good, as are modest quantities of liver.”

Even breakfast should be based predominantly on fats and proteins, and Ede says there are plenty of options if you don’t want meat or fish first thing.

She points to a study under way at the University of Michigan in which researchers are looking at the effects of a keto-style breakfast on type 2 diabetes.

Participants are asked to eat eggs, omelettes, pancakes made with ingredients such as almond flour and cream cheese, and full-fat yoghurt with seeds and berries.

The plan is not carte blanche to eat as much red meat as you like. The NHS advice is that if you eat more than 90g (cooked weight) of red meat a day, you should cut down to 70g.

A recent US-based study of 133,000 people published in Neurology journal by Harvard researchers found that “higher intakes of red meat, particularly processed red meat, was associated with a higher risk of developing dementia and worse cognition”.

Processed meat should be avoided if you want to eat for a healthy brain. The researchers showed that eating two servings a week of processed meat, such as sausages, bacon and salami, raised the risk of dementia by 14 per cent compared with those who ate less than three servings a month.

Those who don’t eat meat, Ede says, can follow the keto diet but need to plan carefully. “If you eat eggs, they are an excellent source of protein, as is tofu,” she says. “But you will also need to eat some pulses and legumes which provide plant proteins.”

Eat fish at least twice a week

“Fatty fish, such as mackerel, sardines and herrings, is definitely something to prioritise,” Ede says.

According to the charity Alzheimer’s Research UK, oily fish including salmon is a source of omega-3 fatty acids that could be beneficial for cognitive health if consumed regularly.

People who eat fish two to three times a week were shown to have healthier blood vessels than those who eat it less than once weekly by neurologists from the University of Bordeaux who said that it could improve circulation to the brain, reducing the risk of Alzheimer’s and vascular dementia.

A study of healthy midlifers in Neurology journal also showed that those who ate a variety of fish and had higher concentrations of omega 3 fats in their bloodstream also had better brain structure and cognitive health in middle age.

Avoid alcohol, refined carbohydrates – and tomatoes

Avoid ultra-processed foods, refined carbohydrates, vegetable oils and too much alcohol, Ede says. “They all cause inflammation, which is harmful to the brain.”

Even red wine, hailed as a brain-booster thanks to its relatively high levels of resveratrol, an antioxidant compound found in grape skins, is less beneficial than many people believe.

“Resveratrol is believed to work by fighting oxidative stress that damages the brain,” Ede says.

“But the tiny amounts of resveratrol in every glass is drowned out by alcohol, which promotes harmful oxidation and also promotes poor sleep patterns associated with developing dementia.”

Try to cut down, she says, and have at least some alcohol-free days each week.

She recommends reducing your intake of members of the nightshade family of vegetables, including peppers, aubergine and tomatoes.

“Nightshades produce glycoalkaloids – pesticides that defend against bacteria, fungi, viruses and insects but which are also neurotoxins that cause damage in the body,” she says.

Should you avoid tomatoes?

“Glycoalkaloids can cross the blood-brain barrier, where they influence alertness, attention and the memory circuits of the brain.”

Eat yoghurt to prevent memory decline

Dairy products are excellent sources of calcium and good sources of other essential nutrients. “They contain high-quality protein that provides all essential amino acids which are the building blocks of protein,” Ede says. “If you can tolerate dairy, the protein it contains is very satiating and you can include it daily.” There are pros and cons to eating dairy as it doesn’t suit everyone, she says. “If you think or know you are sensitive to lactose, look for dairy products with zero grams of carbohydrate per serving,” she suggests. “Some people find fermented dairy products such as hard cheeses, sour cream, and full-fat yoghurt to be gentler on their system because fermentation removes lactose and partially breaks down dairy proteins, so these are an option.”

Researchers from the University of North Carolina reported to the American Society for Nutrition conference that fermented foods such as parmesan and yoghurt prompted gut changes that helped to prevent age-related memory decline.

– Eggs are a superfood for the brain

Eggs – particularly egg yolks, which contain a dense supply of fats and nutrients – are great for the brain, Ede says. She describes them as “a nearly perfect food that provides almost every nutrient we need including some that are otherwise hard to find in a typical diet, such as choline, omega 3 fatty acids and vitamin K2”, all of which play important roles in brain health.

According to UK guidelines set by the National Institute for Health and Care Excellence (Nice), people who are at a high risk of heart disease should consume less than 300mg of dietary cholesterol daily and are advised to limit their intake to three eggs a week, but there is no upper limit for healthy people. “Eggs are the best source of protein for those following a vegetarian diet,” Ede says. “We should all add them to our diet if we can.”

Eat more beans and pulses to boost brain function

All beans, peas and pulses fall into the legume family and a 2023 study in Frontiers in Nutrition showed that regular consumption of pulses, such as pinto beans, black-eyed peas, lentils and chickpeas, seemed to improve brain function in adults. “Legumes are critically important as a protein source for vegetarian and vegan diets,” Ede says.

Eating a couple of handfuls of nuts a day can aid memory

Nuts and seeds contain essential amino acids so are a good source of protein. A 2023 study from Maastricht University published in Clinical Nutrition journal found that eating 60g (a couple of small handfuls) of nuts a day increased blood flow to the left frontal lobe, the bilateral prefrontal cortex and the frontal lobe areas of the brain, with benefits for brain health and memory.

Having nuts can improve your memory.

Eat dark green veg to avoid cognitive decline

A keto diet doesn’t mean avoiding all vegetables, according to Ede. “There are plenty of low-sugar and low-starch plant foods such as lettuce, cucumbers, avocados, mushrooms, asparagus and olives that are great to include for added nutrients and fibre,” she says. “Vegetables have a lot to offer for brain health and those highest in nutrients include cruciferous vegetables, dark green leafy vegetables, beetroot, avocado, pumpkin and butternut squash.”

A high consumption of cruciferous veg, such as broccoli, cabbage, kale, cauliflower and brussels sprouts, which are rich in beneficial flavonoids, was associated with lower levels of cognitive decline in a study of older women by Harvard medical school researchers. Cauliflower also contains an essential nutrient called choline that plays multiple roles in the body, including creating neurotransmitters that allow brain processes such as learning, reading and memory to take place.

Berries can reduce your risk of dementia

Despite its perceived high-sugar content, some fruit is beneficial for the brain. “Fruits are easy to digest and a good choice for people who can tolerate them,” Ede says. “Most fruits contain much lower levels of defensive plant toxins than most vegetables.” Berries are a particularly good choice. “Strawberries, blackberries, blueberries and raspberries are very low in sugar and high in important nutrients,” she says.

Plenty of studies have confirmed the reputation of berries, a rich source of powerful antioxidant plant compounds called flavonoids, as a brain food. One study of 2,800 people aged 50 and older by nutrition scientists at Tufts University’s Human Nutrition Research Center on Ageing showed that a regular intake of blueberries and strawberries provided enough anthocyanins, powerful antioxidants that give berries their red-purple colour, to produce a four-fold lower risk of developing Alzheimer’s disease and related dementias over 20 years.

Avoid wheat, rice and oats

Controversially, according to Ede, grains – the seeds of grasses such as wheat, corn, rice and oats – are “best avoided”.

Many nutrition experts would disagree that these foods should be limited, but Ede argues that they are exceptionally low in important nutrients and very high in so-called antinutrients, natural compounds in foods that interfere with the absorption of nutrients from foods consumed at the same time.

“They can also contain a number of defensive toxins – chemicals in plants, such as lectins, that deter enemies or predators and can cause digestive problems for some people,” she says. “Pre-soaking and boiling your grains for at least an hour will inactivate the lectins, but we still don’t really need grains in our diets.”

This article originally appeared on The Times.

Originally published as Eat more protein: the new way to improve your brain function