An expert on the brain explains how diet can affect mood, behavior, and other things.

The Age of Discovery, which spans the 15th and 16th centuries, is noted for its long maritime trips during which time mariners saw visions of exquisite cuisines and lush landscapes. After months at sea, it was agonizing to learn that these were merely hallucinations. Some seamen cried bitter tears of longing, while others plunged themselves overboard.

A mixture of sophisticated chemicals was thought to contain the solution to these terrifying mirages. But it turned out that the remedy was as easy as drinking lemon juice. These sailors had scurvy, a condition brought on by a lack of vitamin C. Foods high in vitamin C, a necessary micronutrient, including fruits and vegetables.

There is a close relationship between food and the brain, as this well-known instance of early explorers demonstrates, and scientists like myself are trying to understand it. I am primarily interested in how food ingredients and the breakdown products of those ingredients can alter the genetic instructions that regulate our physiology as a scientist studying the neuroscience of nutrition at the University of Michigan.

Aside from that, another goal of my research is to discover how food influences our thoughts, moods, and behaviors. While we can't yet use diet to prevent or treat brain conditions, scientists like myself are learning a lot about the role nutrition plays in the everyday brain processes that shape who we are.

Unsurprisingly, a delicate balance of nutrients is essential for brain health: deficiencies or excesses in vitamins, sugars, fats, and amino acids can influence brain and behavior in either positive or negative ways.

deficits in vitamins and minerals

Similar to vitamin C, deficiencies in other vitamins and minerals can cause nutritional illnesses that harm a person's brain. For instance, pellagra, a disease that results in dementia, is brought on by low dietary amounts of vitamin B3/niacin, which is normally found in meat and fish.

Niacin is required by the body to convert food into energy and building blocks, protect the genetic blueprint from environmental damage, and regulate the number of certain gene products produced. Brain cells, also known as neurons, malfunction and die prematurely in the absence of these critical processes. This can result in dementia.

Niacin synthesis in the brain is decreased or blocked in animal models, which encourages neuronal damage and cell death. However, it has been demonstrated that raising niacin levels can lessen the consequences of neurodegenerative conditions like Parkinson's, Huntington's, and Alzheimer's. Observational studies in people suggest that adequate doses of niacin may offer protection against several diseases, while the results are still preliminary.

Interestingly, pellagra-like symptoms can result from a niacin shortage brought on by excessive alcohol intake.

Iodine is another nutrient that, like niacin, must be obtained from the diet and has been shown to have an impact on brain function. Seafood and seaweed naturally contain it, and iodized salt also contains it. Iodine is a crucial component of thyroid hormones, signaling molecules that are crucial for many biological processes in humans, including growth, metabolism, appetite, and sleep. Low iodine levels interfere with several crucial physiological functions by preventing the generation of enough thyroid hormones.

Iodine is particularly crucial for the human brain's development. Iodine deficiency was a significant global contributor to cognitive dysfunction before this mineral was added to table salt in the 1920s. The progressive increase in IQ scores over the past century is supposed to have been facilitated by the introduction of iodized salt.

Epilepsy diet that is high in fat

Not all nutritional shortages harm the brain. In reality, studies show that individuals with drug-resistant epilepsy, a disorder in which brain cells fire inexplicably, can lessen the frequency of seizures by using a ketogenic diet regimen, in which 80% to 90% of calories are derived from fat.

The body prefers carbohydrates as its primary fuel source. Cells use the breakdown of fats into chemicals known as ketones to acquire energy when they are not readily available, such as during fasting or a ketogenic diet. Significant changes in metabolism and physiology, such as those in hormone levels, the number of neurotransmitters produced by the brain, and the sorts of bacteria residing in the gut, resulting from using ketones as an energy source.

The enhanced production of brain chemicals that can calm neurons and lower levels of inflammatory molecules are two diet-dependent alterations that researchers believe may contribute to the ketogenic diet's capacity to reduce the frequency of seizures. These modifications may also account for the advantages of a ketogenic state on mood and cognitive function, whether achieved through diet or fasting.

Some foods can have a bad impact on your mood and memory.

Saturated fats, sugar, and highly processed foods

The brain might suffer from excessive amounts of specific nutrients. Increased consumption of refined sugars and saturated fats, which are frequently present together in ultra-processed meals, encourages eating in both human and animal models by making the brain less sensitive to the hormonal signals that control feelings of fullness and satisfaction.

It's interesting to note that consuming a lot of these meals also dulls the sense of taste, causing both humans and animals to find food to be less sweet. These sensory changes may have an impact on both the food we choose and the pleasure we derive from it. For instance, studies have shown that eating ice cream every day for two weeks causes a dulling of people's responses to it in reward- and taste-related brain regions of the brain. According to some experts, this reduction in food reward signals may increase desires for even more fatty and sugary foods, much as how smokers experience cravings for cigarettes.

In humans and animal models, high-fat and processed food diets are also linked to worse memory and cognitive performance as well as a higher prevalence of neurodegenerative illnesses. Scientists are still unsure as to whether these effects are brought on by these meals specifically or by the weight gain and insulin resistance that come with consuming these diets over an extended period.

a time frame

This brings up time, a crucial factor in how nutrition affects the brain. Some foods have a rapid impact on how the brain and behavior work, such as for hours or days, but other foods take weeks, months, or even years to have an impact.

For instance, eating a piece of the cake quickly converts a person with drug-resistant epilepsy's fat-burning, ketogenic metabolism into a carbohydrate-burning metabolism, raising the risk of seizures. On the other hand, it takes weeks of sugar consumption for taste and the reward circuits in the brain to change, and it takes months of vitamin C deprivation to develop scurvy. Last but not least, the risk is influenced by years of food exposure combined with other hereditary or lifestyle factors like smoking when it comes to diseases like Alzheimer's and Parkinson's.

In the end, the connection between food and the brain is somewhat like the delicate Goldilocks: We require the right amount of each nutrient—not too little, not too much, but just right.