Studies show these 2 diets can boost brain power

By Alistair Gardiner
Published December 14, 2020

Key Takeaways

As a physician, of course you’re charged with caring for others—but it’s important to look after yourself, too. To ensure that you’re best equipped to practice medicine, you’ll want to keep yourself in top mental shape.

This may mean a change in your eating habits. People tend to think of dieting primarily as a pathway to better physical health, but some eating patterns can work wonders for mental health and cognition as well. According to various studies, there are two popular diets that make a difference when it comes to boosting brain power: ketogenic and low-carbohydrate diets. 

What are ketogenic and low-carb diets?

A ketogenic diet consists of high levels of fats, moderate amounts of protein and very low amounts or no carbohydrates, notes an article in StatPearls. Keto is divided roughly into 55%-60% fat, 30%-35% protein, and 5%-10% carbohydrates. For a typical 2,000 calorie-per-day diet, this is 20 g to 50 g of carbohydrates daily.

A low-carbohydrate diet is very similar, but with slightly higher levels of carbs—typically, up to 25% of your caloric intake, which amounts to 130 g a day or less. For comparison, current US dietary guidelines recommend that carbohydrates make up 45%-60% of your daily calories when eating a 2,000-calorie diet, or 225 g to 325 g of carbohydrates per day.

The primary function of low-carb and keto diets is to change how your body produces energy. Carbohydrates are usually the primary source of fuel for your muscles and other body tissues. When carbs are limited, two metabolic processes begin: gluconeogenesis and ketogenesis.

While your muscles can use stored fat for energy, your brain requires glucose. Gluconeogenesis is what happens when glucose isn’t available through your diet. When this happens, your liver begins to produce its own glucose, using lactic acid, glycerol, and the amino acids alanine and glutamine. 

Ketogenesis works on a similar basis. Once your body is running low on glucose, it begins to produce ketone bodies. During ketogenesis, low blood sugar levels prompt the body to stop storing fat, which can lead to weight loss. This metabolic state is known as nutritional ketosis.

Ketone bodies can be used for energy by the heart, muscles, and kidneys, and they can also cross the blood-brain barrier and become a primary source of energy for the brain. Ketones are sometimes referred to as a “super fuel,” because they can produce far more energy than glucose, allowing the body to maintain efficient functions, even during a period of caloric deficit. They also increase free-radical damage and enhance antioxidant capacity. 

But what does all of this mean for your cognitive health?

How the brain benefits 

The therapeutic effects of a ketogenic diet relate primarily to the characteristics of ketones, according to a review published in the journal Nutrition, in 2019. Factors like oxidative stress and mitochondrial dysfunction are central features of brain degenerative diseases. An increase in ketones, however, can protect against these by increasing mitochondrial respiration and reducing the production of free radicals. 

Ketones may also have a number of other neuroprotective mechanisms, like decreasing inflammatory and proapoptotic activities and increasing levels of neuroprotective agents like neurotrophins and molecular chaperones.

On this basis, research has indicated that a ketogenic diet may be an effective intervention for those facing mental decline—from mild cognitive impairment to Alzheimer disease. 

Research using animal subjects has suggested that a boost in ketones can enhance cognitive function.  A 2018 study published in Scientific Reports, which examined the impacts of a keto diet in mice over 16 weeks, found that it helped reduce levels of amyloid-beta, a hallmark of Alzheimer disease. The study also found that its subjects had increased brain vascular function and healthier gut microbiomes. The study authors concluded that a keto diet could help reduce the risk of Alzheimer disease if used as an early intervention. 

Some studies on humans have also begun to yield results. Another 2018 study, published in Neuroscience Letters, looked at the impact of administering medium-chain triglycerides (MCT), which are ketogenic, to 20 patients with mild-moderate Alzheimer disease over the course of 12 weeks. The subjects underwent neurocognitive tests monthly. Researchers noted that the first test showed no significant cognitive difference between those taking MCT supplements and those on placebos. After 12 weeks, however, patients with MCT supplements demonstrated huge improvements in both immediate and delayed logical memory tests, and digit-symbol coding tests. The study’s authors concluded that a ketogenic diet may have beneficial effects on verbal memory and processing speeds in dementia patients.

Other recent studies have reached similar conclusions, with a ketogenic diet being linked to improved memory performance and general cognitive function—and may help improve blood pressure, blood glucose regulation, and HDL cholesterol levels, according to the authors of the Nutrition article.

Possible dangers

While a keto diet may offer benefits to some, it’s not the right diet for everyone. Even though it’s a proven method for weight loss, the diet can often prompt short-term side effects like nausea, headache, fatigue, difficulty in exercise, and constipation, according to the aforementioned StatPearls article. While staying hydrated can alleviate some of these symptoms, there may also be long-term adverse effects of the diet, including hepatic steatosis, hypoproteinemia, kidney stones, and vitamin and mineral deficiencies.

Beyond that, people with diabetes who try a low-carb diet may experience severe hypoglycemia if their medications are not properly adjusted. Other studies have indicated that the diet is associated with complications that could also land you in the emergency room for things like dehydration or electrolyte disturbances.

Do what works for you

While low-carb and ketogenic diets may not work for everyone, studies consistently point to ketones as having neuroprotective and cognitive enhancing properties. So why wait until dementia becomes a concern? There’s no better time than the present to start improving the health of your brain.

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