During the long seafaring voyages of the 15th and 16th centuries, a period known as the Age of Discovery, sailors reported experiencing visions of sublime foods and verdant fields. The discovery that these were nothing more than hallucinations after months at sea was agonizing. Some sailors wept in longing; 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 of vitamin C, an essential micronutrient that people acquire from eating fruits and vegetables.
Vitamin C is important for the production and release of neurotransmitters, the chemical messengers of the brain. In its absence, brain cells do not communicate effectively with one another, which can lead to hallucinations.
Beyond that, my research is also focused on understanding how food can influence our thoughts, moods and behaviors. While we can’t yet prevent or treat brain conditions with diet, researchers like me are learning a great deal about the role that nutrition plays in the everyday brain processes that make us who we are.
Perhaps not surprisingly, a delicate balance of nutrients is key for brain health: Deficiencies or excesses in vitamins, sugars, fats and amino acids can influence brain and behavior in either negative or positive ways.
Vitamins and mineral deficiencies
As with vitamin C, deficits in other vitamins and minerals can also precipitate nutritional diseases that adversely impact the brain in humans. For example, low dietary levels of vitamin B3/niacin – typically found in meat and fish – cause pellagra, a disease in which people develop dementia.
Niacin is essential to turn food into energy and building blocks, protect the genetic blueprint from environmental damage and control how much of certain gene products are made. In the absence of these critical processes, brain cells, also known as neurons, malfunction and die prematurely, leading to dementia.
In animal models, decreasing or blocking the production of niacin in the brain promotes neuronal damage and cell death. Conversely, enhancing niacin levels has been shown to mitigate the effects of neurodegenerative diseases such as Alzheimer’s, Huntington’s and Parkinson’s. 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 consumption of excessive amounts of alcohol can lead to similar effects as those found with pellagra.
Another example of how a nutrient deficiency affects brain function can be found in the element iodine, which, like niacin, must be acquired from one’s diet. Iodine, which is present in seafood and seaweed, is an essential building block for thyroid hormones – signaling molecules that are important for many aspects of human biology, including development, metabolism, appetite and sleep. Low iodine levels prevent the production of adequate amounts of thyroid hormones, impairing these essential physiological processes.
Not all dietary deficiencies are detrimental to 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 adopting an ultralow-carbohydrate regimen, known as a ketogenic diet, in which 80% to 90% of calories are obtained from fat.
Carbohydrates are the preferred energy source for the body. When they are not available – either because of fasting or because of a ketogenic diet – cells obtain fuel by breaking down fats into compounds called ketones. Utilization of ketones for energy leads to profound shifts 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 think that these diet-dependent changes, especially the higher production of brain chemicals that can quiet down neurons and decrease levels of inflammatory molecules, may play a role in the ketogenic diet’s ability to lower 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 ultraprocessed foods
Excess levels of some nutrients can also have detrimental effects on the brain. In humans and animal models, elevated consumption of refined sugars and saturated fats – a combination commonly found in ultraprocessed foods – promotes eating by desensitizing the brain to the hormonal signals known to regulate satiety.
Interestingly, a diet high in these foods also desensitizes the taste system, making animals and humans perceive food as less sweet. These sensory alterations may 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 dulled when they eat it every day for two weeks. Some researchers think this decrease in food reward signals may enhance cravings for even more fatty and sugary foods, similar to the way smokers crave cigarettes.
High-fat and processed-food diets are also associated with lower cognitive function and memory in humans and animal models as well as a higher incidence of neurodegenerative diseases. However, researchers still don’t know if these effects are due to these foods or to the weight gain and insulin resistance that develop with long-term consumption of these diets.
Time scales
This brings us to a critical aspect of the effect of diet on the brain: time. Some foods can influence brain function and behavior acutely – such as over hours or days – while others take weeks, months or even years to have an effect. For instance, eating a slice of cake rapidly shifts the fat-burning, ketogenic metabolism of an individual with drug-resistant epilepsy into a carbohydrate-burning metabolism, increasing the risk of seizures. In contrast, it takes weeks of sugar consumption for taste and the brain’s reward pathways to change, and months of vitamin C deficiency to develop scurvy. Finally, when it comes to diseases like Alzheimer’s and Parkinson’s, risk is influenced by years of dietary exposures in combination with other genetic or lifestyle factors such as smoking.
In the end, the relationship between food and the brain is a bit like the delicate Goldilocks: We need not too little, not too much but just enough of each nutrient.
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Monica Dus receives funding from the National Science Foundation, the National Institute of Health, the Sloan Foundation, the Rita Allen Foundation, and the Klingenstein Foundation. She is affiliated with The University of Michigan, Ann Arbor. She is on the Advisory Board for the Trends in Endocrinology & Metabolism journal, the Editorial Board for the Chemical Senses journal, and the Advisory Board for the University of Michigan Museum of Natural History.
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3 ways to soothe your sunburn when it starts to peel
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DEAR MAYO CLINIC: As a woman in my 40s, I've experienced a wide variety of diet fads come and go. One week I read it’s bad to eat carbs. The next week, it’s full-fat dairy products. I’ve seen articles that say I should only eat between certain hours of the day. There is a lot of contradictory information. How do I distinguish between nutrition myth and fact?
ANSWER: Among the sea of information about nutrition is a tide of inaccuracies. It can seem challenging to know what is good for you.
Here are 10 nutrition myths debunked:
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DEAR MAYO CLINIC: As a woman in my 40s, I've experienced a wide variety of diet fads come and go. One week I read it’s bad to eat carbs. The next week, it’s full-fat dairy products. I’ve seen articles that say I should only eat between certain hours of the day. There is a lot of contradictory information. How do I distinguish between nutrition myth and fact?
ANSWER: Among the sea of information about nutrition is a tide of inaccuracies. It can seem challenging to know what is good for you.
It may take some planning and time in the kitchen, but eating healthy on a budget is possible.
Some helpful hints include planning meals and snacks around sales and creating a shopping list. Stock up on seasonal vegetables and fruits as well as staples, such as brown rice, whole-wheat pasta, dried beans and lentils, especially when there is a sale. Consider purchasing frozen or canned fruits and vegetables as an alternative to fresh products. Be sure to check the ingredient list to avoid items with added sugars or salt.
It may take some planning and time in the kitchen, but eating healthy on a budget is possible.
Some helpful hints include planning meals and snacks around sales and creating a shopping list. Stock up on seasonal vegetables and fruits as well as staples, such as brown rice, whole-wheat pasta, dried beans and lentils, especially when there is a sale. Consider purchasing frozen or canned fruits and vegetables as an alternative to fresh products. Be sure to check the ingredient list to avoid items with added sugars or salt.
Unless you have celiac disease or gluten intolerance, you don't need to avoid gluten.
Gluten is the protein found in wheat, barley and rye. Whole-wheat products have great nutritional benefits, including essential B vitamins and fiber. Be mindful when manufacturers remove gluten, as additional sugar, salt or refined starches often are added to make up the difference in flavor and texture. If you follow a gluten-free diet for medical reasons, check the ingredient list and Nutrition Facts label to make sure you choose a healthy option.
Unless you have celiac disease or gluten intolerance, you don't need to avoid gluten.
Gluten is the protein found in wheat, barley and rye. Whole-wheat products have great nutritional benefits, including essential B vitamins and fiber. Be mindful when manufacturers remove gluten, as additional sugar, salt or refined starches often are added to make up the difference in flavor and texture. If you follow a gluten-free diet for medical reasons, check the ingredient list and Nutrition Facts label to make sure you choose a healthy option.
Although unrefined sugar options may contain a small number of vitamins and minerals, the advantage is minimal. They are still considered added sugar and contribute to the recommended daily limit on added sugar in the diet.
Although unrefined sugar options may contain a small number of vitamins and minerals, the advantage is minimal. They are still considered added sugar and contribute to the recommended daily limit on added sugar in the diet.
The fat-free and low-fat diet trend is a thing of the past — the ’80s and ’90s to be exact. Yet, some people are still scared of fat.
This shouldn't be the case, as fat has beneficial functions, like protecting our organs, maintaining cell membranes, promoting growth and development, and absorbing essential vitamins. Be aware that fats aren't created equal, though. Choose heart-healthy unsaturated fats, such as olive and canola oil, nuts, nut butters, and avocados over those that are high in saturated and transfats, such as fatty meats and high-fat dairy products.
The fat-free and low-fat diet trend is a thing of the past — the ’80s and ’90s to be exact. Yet, some people are still scared of fat.
This shouldn't be the case, as fat has beneficial functions, like protecting our organs, maintaining cell membranes, promoting growth and development, and absorbing essential vitamins. Be aware that fats aren't created equal, though. Choose heart-healthy unsaturated fats, such as olive and canola oil, nuts, nut butters, and avocados over those that are high in saturated and transfats, such as fatty meats and high-fat dairy products.
The low-carb diet is a fad diet that has continued to make an appearance over the years. It gives carbohydrates — fruit and whole grains included — a bad reputation.
People who followed this diet have had success with weight loss, but anytime someone eliminates highly processed carbohydrates foods, such as chips, cookies, white bread and potatoes smothered in butter and gravy, they would be expected to have the same results. Any diet or eating program that eliminates an entire food group gets a red flag, as one is likely to miss out on vital nutrients.
The low-carb diet is a fad diet that has continued to make an appearance over the years. It gives carbohydrates — fruit and whole grains included — a bad reputation.
People who followed this diet have had success with weight loss, but anytime someone eliminates highly processed carbohydrates foods, such as chips, cookies, white bread and potatoes smothered in butter and gravy, they would be expected to have the same results. Any diet or eating program that eliminates an entire food group gets a red flag, as one is likely to miss out on vital nutrients.
There’s little evidence that dietary cleanses do any of the things they promise.
The fact is you don't need to purchase a product to cleanse your body. Your liver, kidneys and gastrointestinal tract do a good job of detoxing it every day. If you're looking to rejuvenate your body, focus on eating more whole foods, drinking water and removing highly processed foods from your diet.
There’s little evidence that dietary cleanses do any of the things they promise.
The fact is you don't need to purchase a product to cleanse your body. Your liver, kidneys and gastrointestinal tract do a good job of detoxing it every day. If you're looking to rejuvenate your body, focus on eating more whole foods, drinking water and removing highly processed foods from your diet.
While late-night snacking can lead to weight gain or prevent weight loss, it's not because of the time on the clock. Instead, it’s about why you're eating.
It is common to reach for food for reasons other than physical hunger in the evening, whether it be a habit, boredom or craving. Be mindful about what you eat more so than when.
While late-night snacking can lead to weight gain or prevent weight loss, it's not because of the time on the clock. Instead, it’s about why you're eating.
It is common to reach for food for reasons other than physical hunger in the evening, whether it be a habit, boredom or craving. Be mindful about what you eat more so than when.
Unfortunately, no foods burn fat, make you lose weight more quickly or increase your metabolism enough to affect weight loss.
Diets that focus on single foods, like those mentioned above, are restrictive and lack nutrients the body needs. They’re also unsustainable, and any weight loss that may occur is a result of calorie restriction and will likely come back once you discontinue.
Unfortunately, no foods burn fat, make you lose weight more quickly or increase your metabolism enough to affect weight loss.
Diets that focus on single foods, like those mentioned above, are restrictive and lack nutrients the body needs. They’re also unsustainable, and any weight loss that may occur is a result of calorie restriction and will likely come back once you discontinue.
The 2020-2025 Dietary Guidelines for Americans recommends having no more than 2,300 milligrams of sodium per day. The average American consumes 3,400 milligrams of sodium per day. The problem isn't as easy as taking the salt shaker off the table, though.
Much of the excess sodium that Americans consume from their diet comes from the salts added to processed, ready-to-eat foods and restaurant meals. Limit the processed foods and enjoy more fresh, home-cooked meals.
The 2020-2025 Dietary Guidelines for Americans recommends having no more than 2,300 milligrams of sodium per day. The average American consumes 3,400 milligrams of sodium per day. The problem isn't as easy as taking the salt shaker off the table, though.
Much of the excess sodium that Americans consume from their diet comes from the salts added to processed, ready-to-eat foods and restaurant meals. Limit the processed foods and enjoy more fresh, home-cooked meals.
Many products labeled low-fat or fat-free contain added sugar or sodium to make up for the loss of flavor when removing or reducing fat.
In addition, fat helps with satiety — making you feel fuller longer. Choosing a fat-free product to reduce calories can backfire, as you may find yourself snacking soon after.
My best advice if you want to eat healthy is to always look at the Nutrition Facts label when choosing among fat-free, low-fat and regular. Pay attention to sugar and sodium content. Choose whole foods versus processed, and make sure you are drinking enough water. If you feel you need a more specific menu, ask your health care professional for a referral to a dietitian or nutritionist. — Allyn Wergin, R.D.N., Clinical Nutrition Services, Mayo Clinic Health System, New Prague and Le Suer, Minnesota
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(Mayo Clinic Q & A is an educational resource and doesn’t replace regular medical care. E-mail a question to MayoClinicQ&A@mayo.edu. For more information, visit www.mayoclinic.org.)
Many products labeled low-fat or fat-free contain added sugar or sodium to make up for the loss of flavor when removing or reducing fat.
In addition, fat helps with satiety — making you feel fuller longer. Choosing a fat-free product to reduce calories can backfire, as you may find yourself snacking soon after.
My best advice if you want to eat healthy is to always look at the Nutrition Facts label when choosing among fat-free, low-fat and regular. Pay attention to sugar and sodium content. Choose whole foods versus processed, and make sure you are drinking enough water. If you feel you need a more specific menu, ask your health care professional for a referral to a dietitian or nutritionist. — Allyn Wergin, R.D.N., Clinical Nutrition Services, Mayo Clinic Health System, New Prague and Le Suer, Minnesota
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(Mayo Clinic Q & A is an educational resource and doesn’t replace regular medical care. E-mail a question to MayoClinicQ&A@mayo.edu. For more information, visit www.mayoclinic.org.)
Fast food value meals are quick, yummy and sometimes inexpensive. What you save at the drive-thru, however, might cost you more in health care bills if you indulge in too many of them.
Recently, Eat This, Not That analyzed these meals and found these combos will put you over the limit for calories, sodium, fat and sugar “before you’ve even finished your meal.”
“If you are eating these occasionally, and you feel good, there’s nothing to worry about,” holistic nutritionist Kristen Ciccolini told the website. “The main thing I’d be concerned with if consuming these meals regularly is the sodium content.”
For context, the 2020-2025 Dietary Guidelines for Americans recommends less than 2,300 milligrams of sodium per day; Cleveland Clinic recommends about 44 to 77 grams of fat per day, if you eat 2,000 calories; and the Mayo Clinic says between 900 and 1,300 calories of a 2,000 calorie diet — or 225-325 grams — should be from carbohydrates.
If you’re trying to eat healthier, here are seven meals you’ll likely want to avoid.
Fast food value meals are quick, yummy and sometimes inexpensive. What you save at the drive-thru, however, might cost you more in health care bills if you indulge in too many of them.
Recently, Eat This, Not That analyzed these meals and found these combos will put you over the limit for calories, sodium, fat and sugar “before you’ve even finished your meal.”
“If you are eating these occasionally, and you feel good, there’s nothing to worry about,” holistic nutritionist Kristen Ciccolini told the website. “The main thing I’d be concerned with if consuming these meals regularly is the sodium content.”
For context, the 2020-2025 Dietary Guidelines for Americans recommends less than 2,300 milligrams of sodium per day; Cleveland Clinic recommends about 44 to 77 grams of fat per day, if you eat 2,000 calories; and the Mayo Clinic says between 900 and 1,300 calories of a 2,000 calorie diet — or 225-325 grams — should be from carbohydrates.
If you’re trying to eat healthier, here are seven meals you’ll likely want to avoid.
How inflation pushed KFC to put chicken feet on the menu in China
AP Photo/Diether Endlicher
“Two all-beef patties, special sauce, lettuce, cheese on a sesame seed bun” made for a good commercial but not a healthy meal.
“This meal contains artery-clogging fat from the meat and cheese, along with added sugar from the soda,” Lisa Young, a registered dietitian nutritionist, told Eat This, Not That.
Per meal
1,080 calories
45 g fat (13 g saturated fat)
1,325 mg sodium
144 g carbohydrates (7 g fiber; 65 g sugar)
30 g protein
AP Photo/Diether Endlicher
“Two all-beef patties, special sauce, lettuce, cheese on a sesame seed bun” made for a good commercial but not a healthy meal.
“This meal contains artery-clogging fat from the meat and cheese, along with added sugar from the soda,” Lisa Young, a registered dietitian nutritionist, told Eat This, Not That.
How inflation pushed KFC to put chicken feet on the menu in China
AP Photo/Wilfredo Lee, File
On their own, wraps can be healthy. But when you pair them with curly fries and a soft drink, any benefits are negated.
“With 1,220 calories, this meal contains more than half of your calories for the day,” Young said. “And both the fries and soda provide virtually no health value.”
Per meal
1,220 calories
57 g fat (12 g saturated fat)
2,310 mg sodium
140 g carbohydrates (9 g fiber; 56 g sugar)
46 g protein
AP Photo/Wilfredo Lee, File
On their own, wraps can be healthy. But when you pair them with curly fries and a soft drink, any benefits are negated.
“With 1,220 calories, this meal contains more than half of your calories for the day,” Young said. “And both the fries and soda provide virtually no health value.”
How inflation pushed KFC to put chicken feet on the menu in China
AP Photo/Mike Stewart, File
According to Young, this meal has too much sodium. “This meal contains over 70% of the daily value for saturated fat and more than 60% of the daily value for sodium, making you want to skip it,” she said.
Per meal
1,260 calories
57 g fat (22 g saturated fat)
1,685 mg sodium
140 g carbohydrates (7 g fiber; 63 g sugar)
53 g protein
AP Photo/Mike Stewart, File
According to Young, this meal has too much sodium. “This meal contains over 70% of the daily value for saturated fat and more than 60% of the daily value for sodium, making you want to skip it,” she said.
How inflation pushed KFC to put chicken feet on the menu in China
AP Photo/Candice Choi
Ciccolini urges caution for anyone craving melted cheese over a half-pound of beef.
This one meal has more sodium, and more than enough fat and carbs, for the entire day. It also has one of the higher saturated fat contents of the value meals.
Per meal
1,310 calories
61 g fat (17 g saturated fat)
3,370 mg sodium
141 g carbohydrates
54 g protein
AP Photo/Candice Choi
Ciccolini urges caution for anyone craving melted cheese over a half-pound of beef.
This one meal has more sodium, and more than enough fat and carbs, for the entire day. It also has one of the higher saturated fat contents of the value meals.
What we eat matters, and having just the right amount of essential nutrients is key to our overall health. Niusha Shodja and Saina Heshmati, Storylab, CC BY-NC-ND