Neuroscientist explains how diet can affect mood, behavior, and more

It's important to pay attention to what we put in our bodies, as getting the appropriate balance of nutrients is crucial to our well-being.Rasulovs/istockphoto

Long-distance sailors in the Age of Discovery (15th to 16th century) sometimes had dreams of delicious, exotic meals and lush, green fields. After spending a significant amount of time at sea, the excruciating realization that these were merely hallucinations came about. Some of the sailors wept out of longing, while others committed suicide by jumping overboard. Lemon juice was shown to be the most effective treatment for these terrifying mirages, rather than the more complicated chemical cocktail that was formerly thought to be the only solution. These sailors were suffering from scurvy, which is a sickness that is brought on by a lack of vitamin C. Vitamin C is an essential micronutrient that may be obtained by eating fruits and vegetables. Producing and releasing neurotransmitters, which are the brain's chemical messengers, requires a healthy amount of vitamin C. Vitamin C is essential for this process. Without it, the brain cells are unable to communicate with one another in an efficient manner, which might result in hallucinations.

Scientists like Monica Dup are trying to determine the nature of the complex relationship between what we eat and how our brains function, as demonstrated by this well-known tale of early explorers. Monica Dup is a researcher at the University of Michigan who specializes in the neuroscience of nutrition. Her primary area of interest is how different components of food and the chemicals that result from their breakdown might influence the genetic instructions that control human physiology. In addition to that, the primary objective of her research is to gain a knowledge of the ways in which food can affect our thoughts, emotions, and behaviors. Researchers like Monica are gaining a lot of knowledge about the role that nutrition plays in the day-to-day brain processes that determine who we are as individuals. This is despite the fact that we are unable to prevent or treat brain conditions with diet at this time. It should not come as much of a surprise that maintaining a delicate balance of nutrients is essential for brain health. Deficiencies or excesses in vitamins, carbohydrates, fats, and amino acids can influence the brain and behavior in either a negative or good way.

In humans, nutritional deficiencies can lead to diseases that have a negative impact on brain function, just like a lack of vitamin C can. However, deficiencies in other vitamins and minerals can have the same effect. Pellagra, for instance, is a disease in which patients acquire dementia as a result of low amounts of vitamin B3 and niacin in their diets; these nutrients are commonly present in meat and fish. Niacin is necessary for the conversion of food into energy and building blocks, the protection of the genetic blueprint from damage caused by the environment, and the regulation of the amount of particular gene products that are produced. In the absence of these essential activities, brain cells, sometimes referred to as neurons, become dysfunctional and pass away at an earlier age, which can contribute to dementia. Animal studies have shown that inhibiting or completely stopping the production of niacin in the brain leads to an increase in neuronal damage and cell death.

On the other hand, increasing the amounts of niacin in the body has been found to reduce the severity of the symptoms associated with neurodegenerative illnesses such as Alzheimer's, Huntington's, and Parkinson's. Although the results of observational studies conducted on humans have suggested that adequate doses of niacin may protect against certain diseases, these findings are not yet definitive. Pellagra-like symptoms can be brought on by a lack of niacin, which can also be brought on by drinking an excessive amount of alcohol. This is a very interesting phenomenon. Iodine is another example of how a deficit in a nutrient can influence brain function. Iodine, like niacin, is something that must be obtained through one's diet in order to be of any use to the body.

Iodine is an essential building block for thyroid hormones, which are signaling molecules that are vital for many aspects of human biology, including development, metabolism, appetite, and sleep. Iodine may be found in fish and seaweed, both of which are abundant food sources. Iodine deficiency inhibits the creation of sufficient quantities of thyroid hormones, which in turn disrupts the functioning of many vital physiological systems. Prior to the addition of iodine to table salt in the 1920s, iodine deficiency was one of the leading causes of cognitive disability around the globe according to WHO. Iodine plays a particularly crucial role in the development of the human brain. It is widely believed that the progressive increase in IQ scores over the previous century can be attributed, in part, to the widespread use of iodized salt.

There are some dietary deficits that do not pose a risk to the brain. Studies have shown that people with a form of epilepsy known as drug-resistant epilepsy, which is a condition in which brain cells fire in an uncontrolled manner, can reduce the number of seizures they experience by adhering to an extremely low-carbohydrate regimen known as a ketogenic diet, in which anywhere from 80–90% of one's daily calories come from fat. The body prefers to get its energy from carbohydrates rather than any other source. Cells obtain fuel by breaking down fats into compounds called ketones during times when glucose and other sugars are not readily available. This can occur as a result of fasting or from following a ketogenic diet.

When ketones are used for energy, profound changes occur in the body's metabolism and physiology. These changes can be seen in areas such as the levels of hormones that are circulating in the body, the amount of neurotransmitters that are produced by the brain, and the types of bacteria that are found in the gut. Seizure frequency may be reduced by the ketogenic diet due to the dietary-dependent changes discussed above, including the increased production of brain chemicals that can calm down neurons and decrease levels of inflammatory molecules.

These alterations may also account for the positive effects of entering a ketogenic state on cognition and emotion, whether through dietary means or fasting.

Sugar, saturated fats and ultraprocessed foods

Some nutrients, when present in high enough concentrations, might actually be harmful to the brain. Both people and animal models have shown that eating a lot of ultraprocessed foods high in refined sugars and saturated fats makes them less sensitive to the hormonal signals in the brain that govern fullness. Consuming a lot of these foods has the interesting side effect of dulling the sense of taste, so that both animals and humans begin to find sweet foods less appetizing. These changes in perception may influence both our food preferences and the pleasure we derive from eating. Scientific studies have shown that after two weeks of daily ice cream consumption, people's taste and reward responses to the dessert become less intense. It has been hypothesized by some researchers that a decline in these reward signals may increase the desire for high-calorie, high-sugar foods in a manner analogous to that experienced by smokers.

Cognitive impairment, memory loss, and an increased risk of neurodegenerative disease have all been linked to high-fat, processed-food diets in people and animal models. Long-term consumption of these diets is associated with weight gain and insulin resistance, however it is unclear whether or not these effects are caused by the foods themselves.

Thus, we reach a crucial aspect of the influence of diet on the brain: duration. The effects of eating certain meals on one's brain and behavior may be immediate (over the course of a few hours or days), or they may not manifest themselves for weeks, months, or even years. A person with drug-resistant epilepsy, for instance, is more likely to have seizures after eating a piece of cake because it rapidly converts their fat-burning, ketogenic metabolism into a carbohydrate-burning metabolism. However, it takes months of vitamin C deficiency to produce scurvy and weeks of sugar consumption to alter taste and the brain's reward circuits. Finally, dietary exposures over many years, in addition to other genetic or lifestyle variables like smoking, might affect risk for diseases like Alzheimer's and Parkinson's.

The connection between what we eat and how it affects our brains is, ultimately, a bit Goldilocks-like: we require neither too little nor too much of any given vitamin.

Source: The conversation