Summary: Researchers assess how our choice of diet can impact our moods and behaviors, and explain how specific diets can help manage certain neurological conditions.
Source: The conversation
During the long sea voyages of the 15th and 16th centuries, a period known as the Age of Discovery, sailors reported seeing visions of sublime food and verdant fields. The discovery that they were only hallucinations after months at sea was agonizing. Some sailors wept with nostalgia; others threw themselves overboard.
The cure for these harrowing mirages turned out to be not a concoction of complex chemicals, as once suspected, but rather the simple antidote of lemon juice. These sailors suffered from scurvy, a disease caused by a deficiency in vitamin C, an essential micronutrient that people acquire by eating fruits and vegetables.
Vitamin C is important for the production and release of neurotransmitters, the brain’s chemical messengers. Without it, brain cells do not communicate effectively with each other, which can lead to hallucinations.
As this famous example from early explorers illustrates, there is an intimate connection between food and the brain, one that researchers like me are striving to unravel. As a scientist studying nutritional neuroscience at the University of Michigan, my primary interest is in how components of foods and their breakdown products can alter the genetic instructions that control our physiology.
Beyond that, my research also aims to understand how food can influence our thoughts, moods, and behaviors. Although we can’t yet prevent or treat brain conditions with diet, researchers like me are learning a lot about the role nutrition plays in the daily brain processes that make us who we are.
It is perhaps unsurprising that a delicate balance of nutrients is essential for brain health: deficiencies or excesses of vitamins, sugars, fats and amino acids can influence the brain and the behavior of negative or positive way.
Vitamin and mineral deficiencies
As with vitamin C, deficiencies of other vitamins and minerals can also precipitate nutritional diseases that negatively impact the brain in humans. For example, low dietary levels of vitamin B3/niacin – commonly found in meat and fish – cause pellagra, a disease in which people develop dementia.
Niacin is essential for converting food into energy and building blocks, protecting the genetic imprint from environmental damage, and controlling the amount of certain genetic products produced. Without these critical processes, brain cells, also called neurons, malfunction and die prematurely, leading to dementia.
In animal models, decreasing or blocking niacin production in the brain promotes neuronal damage and cell death. Conversely, increased niacin levels have been shown to lessen the effects of neurodegenerative diseases such as Alzheimer’s disease, Huntington’s disease and Parkinson’s disease. Observational studies in humans suggest that sufficient levels of niacin may protect against these diseases, but the results are still inconclusive.
Interestingly, niacin deficiency caused by excessive alcohol consumption can lead to effects similar to those seen with pellagra.
Another example of how nutrient deficiency affects brain function can be found in the element iodine, which, like niacin, must be acquired from one’s diet. Iodine, found in seafood and seaweed, is an essential building block of thyroid hormones – signaling molecules important for many aspects of human biology, including development, metabolism, appetite and sleep. . Low levels of iodine prevent the production of adequate amounts of thyroid hormones, impairing these essential physiological processes.
Iodine is particularly important for the development of the human brain; before table salt was supplemented with this mineral in the 1920s, iodine deficiency was a leading cause of cognitive impairment worldwide. The introduction of iodized salt is thought to have contributed to the gradual increase in IQ scores over the past century.
Ketogenic diet for epilepsy
Not all nutritional deficiencies harm the brain. In fact, studies show that people with drug-resistant epilepsy — a condition in which brain cells fire uncontrollably — can reduce the number of seizures by eating a very low-carb diet, known as the name of ketogenic diet, in which 80% to 90% of calories are obtained from fat.
Carbohydrates are the body’s preferred source of energy. When it’s not available — either because of fasting or a ketogenic diet — cells get fuel by breaking down fat into compounds called ketones. Using ketones for energy leads to profound changes in metabolism and physiology, including the levels of hormones circulating in the body, the amount of neurotransmitters produced by the brain, and the types of bacteria living in the gut. .
Researchers believe that these diet-dependent changes, specifically the higher production of brain chemicals that can calm neurons and reduce levels of inflammatory molecules, may play a role in the ability of the ketogenic diet to reduce the number of seizures. . These changes may also explain the benefits of a ketogenic state — either through diet or fasting — on cognitive function and mood.
Sugar, saturated fats and ultra-processed foods
Excessive levels of certain nutrients can also have adverse effects on the brain. In humans and animal models, a high intake of refined sugars and saturated fat – a combination commonly found in ultra-processed foods – promotes eating by desensitizing the brain to hormonal signals known to regulate satiety. .
Interestingly, a diet high in these foods also desensitizes the taste system, causing animals and humans to perceive foods as less sweet. These sensory alterations can affect food choice as well as the reward we get from food.
For example, research shows that people’s responses to ice cream in brain areas important for taste and reward are dampened when they eat it every day for two weeks. Some researchers believe that this decrease in food reward cues may increase cravings for even more fatty and sugary foods, similar to how smokers crave cigarettes.
Diets high in fat and processed foods are also associated with reduced cognitive function and memory in humans and animal models, as well as a higher incidence of neurodegenerative diseases. However, researchers still don’t know whether these effects are due to these foods or to the weight gain and insulin resistance that develop with long-term consumption of these diets.
This brings us to a critical aspect of the effect of food on the brain: time. Some foods can have an acute influence on brain function and behavior – for example over hours or days – while others take weeks, months or even years to have an effect.
For example, eating a slice of cake rapidly changes the fat-burning ketogenic metabolism of an individual with drug-resistant epilepsy to a carbohydrate-burning metabolism, thereby increasing the risk of seizures.
In contrast, it takes weeks of sugar consumption for taste and brain reward pathways to change, and months of vitamin C deficiency to develop scurvy.
Finally, when it comes to diseases like Alzheimer’s disease and Parkinson’s disease, the risk is influenced by years of dietary exposure in combination with other genetic or lifestyle factors, such as smoking.
Ultimately, the relationship between food and the brain is a bit like the delicate Goldilocks: we don’t need too little or too much, but just enough of each nutrient.
About this diet and psychology research news
Author: Monica Dus
Source: The conversation
Contact: Monica Dus – The Conversation
Image: Image is in public domain
Diet May Influence Mood, Behavior and More – Neuroscience News