A Scientist’s Guide to Eating for Brain Health
Too often, when we think about our diet, we’re thinking about how it affects our bodies, not our brains. But as Lisa Mosconi, a neuroscientist and the author of Brain Food, points out, the things we eat affect a lot more than what we look like. Our diet affects our minds and shapes the way we think, feel, and age. As Mosconi, the associate director of the Alzheimer’s Prevention Clinic at Weill Cornell Medical College in New York City, tells us, “What the brain needs to eat differs from what the rest of the body needs to eat.” Turns out the brain’s number one favorite food is glucose—a carbohydrate. And, Mosconi points out, not all glucose is the same. Having grown up in Florence, Italy, she knows a thing or two about good food and what a difference the quality of the food makes to the brain’s overall health. That’s why, in her practice, Mosconi combines neuroscience with cooking. Mosconi says, “I spend nearly as much time examining cookbooks as medical journals. Cookbooks are essential to contemporary brain science, because every one of those recipes shapes our brains just as it builds our bodies.”
(For more information on diet and brain health, see our goop PhD article on Alzheimer’s disease.)
A Q&A with Lisa Mosconi, PhD
What does our brain need nutritionally?
In the course of my research, we’ve examined a highly specialized system called the blood-brain barrier, which determines what nutrients can and can’t go inside the brain (which I call brain-essential nutrients). There are also gates in the brain that open and close depending on whether the brain is “hungry.” No other organs in the body have the same strict rules.
“The brain has its own carefully selected diet, and what’s good for our brain is good for the rest of our body, but not necessarily the other way around.”
To function best, the brain requires around forty-five nutrients that are as distinct as the molecules, cells, and tissues they shape. The brain, being radically efficient, makes many of these nutrients itself, and only accepts whatever else it needs from our diets. Put simply: Everything in the brain that isn’t made by the brain itself is imported from the food we eat.
Whether built in your head or in your kitchen, brain-essential nutrients belong to the five major nutrient groups: proteins (broken down into smaller units called amino acids), carbohydrates, fats, vitamins, and minerals. Among these, the brain needs:
a specific kind of fat called long-chain polyunsaturated fatty acids (PUFAs, like the omega-3 fatty acids found in salmon)
essential amino acids from protein
a specific kind of carbohydrate called glucose
all sorts of vitamins and minerals, especially those with antioxidant effects, like vitamin A, vitamin C, vitamin E, and selenium—and also iron, copper, and zinc
While your body needs many other nutrients to fully function, these are the only ones that will make it past the brain barrier.
There is a lot of different info out there on fat—what kind of fat does the brain need and how much? What are some of the best sources?
Many people believe that eating fat is good for the brain. The argument is that since the brain is “made of fat,” eating fat is good for your brain. From a scientific and clinical perspective, this statement is problematic for two reasons:
First, not all fat is created equal. For example, some processed foods contain fat, but that fat isn’t good for your brain.
Second, and more importantly, although the human brain contains fat, the majority of brain fat does not come from the foods we eat.
Three facts to know about the brain and fat:
Unlike every other organ in the body, the brain cannot burn fat to make energy. Therefore the brain has no use for fatty foods rich in the kind of fat that makes energy: saturated fat. Additionally (and contrary to claims in many popular diet books), the brain is able to make a good amount of the saturated fat that it needs locally; for the most part, it doesn’t require restocking. The only time the brain needs to import saturated fat is during childhood and early adolescence, when our neurons are growing at light speed and need the extra support. After adolescence, by and large, the brain stops absorbing this kind of fat from the bloodstream.
The brain has no use for dietary cholesterol. The brain makes all of its own cholesterol when we are infants and our brains are growing. After that, brain cholesterol is sealed away from the rest of the body.
The only kind of fat the brain needs throughout a lifetime is PUFA. This is a particular type of fat present in fish, shellfish, and some nuts and seeds, all of which belong to a healthy brain diet. Among all possible types of PUFAs, two varieties, omega-3 and omega-6, are the best for promoting brain health. It is important to include both of these PUFAs in our daily diet as they serve two very different but related functions.
Omega-6 fatty acids have pro-inflammatory properties. In biology, inflammation refers to the activation of your immune system and how well it protects you from danger. Omega-6s play a role in this process by encouraging our bodies and brains to mount an inflammatory response in the case of a wound or an infection or simply when we’re sick. Omega-3 fatty acids turn down this response once the danger is no longer present and are therefore considered anti-inflammatory.
While both types of PUFAs are beneficial, their relative proportion within a diet matters. Studies have demonstrated that a balance between these two PUFAs is essential for proper brain health, neuronal communication, and the maintenance of a healthy immune system. For the brain, this balance depends entirely on our food choices.
Research has suggested that a two-to-one ratio of omega-6 to omega-3 is a good balance. It is estimated, however, that Americans consume twenty or thirty times more omega-6 than omega-3, making the typical Western diet (processed food, fast food, low in fruit and vegetables) inflammatory in nature. By eating too much omega-6-rich food and too little omega-3-rich food, we may be putting ourselves at risk for many diseases, including Alzheimer’s. We need to make sure our diets support this important and delicate two-to-one balance.
THE IDEAL FAT BALANCE
We recommend a two-to-one ratio of omega-6 to omega-3. Here are some ways to get them:
Omega-6s generally need to be reduced for many people to get to a two-to-one ratio. They are present in vegetable oils from canola, corn, peanuts, and sunflower seeds, as well as fatty animal foods, such as bacon and chicken fat.
Omega-3s commonly need to be increased for many people. They can be found in marine sources, including fish, like salmon, mackerel, sardines, and cod. They also come from plant sources, especially flaxseeds, walnuts, chia seeds, and wheat germ, and some sea vegetables, such as spirulina.
Research shows that diets with the lowest amounts of omega-3s relative to other fats are associated with the highest rates of brain shrinkage over time and the highest risk of Alzheimer’s. Diets with the highest amounts of omega-3s are associated with the healthiest, most “youthful” brains.”
Luckily, it doesn’t take much to reach our brain-fat goals. A small piece of Alaskan salmon (just three ounces) provides about two grams of omega-3s. Pair it with a handful of almonds, and if fish isn’t an option, flaxseeds and chia seeds are good alternatives.
Why does the brain need so much glucose?
The brain uses more energy than any other human organ, up to 20 percent of the body’s total burn. And when the brain needs energy, it relies on a simple sugar called glucose. The blood-brain barrier has evolved to allow glucose to pass right through it to feed the billions of cells that make up your brain.
If you’ve ever had a headache or experienced brain fog when your blood sugar was low, you’re aware of the downside of the brain’s reliance on glucose: the vulnerability to drops in blood sugar levels. Similarly, high blood sugar can cause systems in your body to run out of control. For many, high blood sugar isn’t a medical condition or a genetic outcome but rather the result of the food you’ve eaten (or not eaten). For optimized brain function, the goal is to provide your brain with adequate amounts of glucose, while keeping your blood sugar levels stable.
There are different forms of carbohydrates: Simple carbohydrates, such as honey, provide quick energy. Complex carbohydrates, such as whole wheat and brown rice, are more difficult for your body to break down and provide time-released energy. The slower breakdown results in less of a blood sugar spike. Unfortunately, as a society, we eat too many unhealthy refined sugars (mostly white foods, like sugar, pasta, and baked goods) and not enough of the glucose that makes us smart.
“For optimized brain function, the goal is to provide your brain with adequate amounts of glucose, while keeping your blood sugar levels stable.”
A good way to evaluate your sugar intake is to look at a food’s glycemic load. The glycemic-load system ranks foods in terms of how quickly they raise your blood sugar levels in relationship to the amount of fiber a food contains. The more fiber, the lower the food’s effects on insulin. Excellent sources of lower-glycemic carbohydrates include sweet potatoes or yams (eaten with the skin on); fiber-rich fruits, like berries and grapefruit; and vegetables, such as pumpkin, butternut squash, and carrots. Other foods, such as legumes (lentils, garbanzo beans, black beans) and whole grains (with their husks still on), also provide you with more-stable blood sugar levels while at the same time being a good source of brain-essential glucose.
There are great natural sources of glucose that aren’t “sugary,” such as onions, turnips, and rutabaga. Honey and maple syrup are more obvious (and excellent) natural sources, as are fruits, like kiwifruit, grapes, raisins, and dates. There’s also “nature’s candy,” the red beet—a single beet contains 31 percent of all the glucose you need in a day.
If you have a sweet tooth, don’t despair: Some foods that qualify as treats still have an overall low glycemic load. For example, a square of organic dark chocolate (80 percent or higher), preferably sugar-free or sweetened with honey, has a low glycemic load, which makes it satisfying without the sugar rush.
To make your brain happy, focus on low-glycemic high-fiber foods as the main source of carbs in your diet, and indulge in high-glycemic foods only in small amounts, and infrequently at that. As the saying goes, everything in moderation.
What ingredients or foods are most problematic when it comes to the brain?
Avoid excess saturated fat. It has been well established that high levels of these fats have a negative impact on our mental capacities, increasing our risk of dementia. A high intake of saturated fat can cause inflammation throughout the body and reduce oxygen flow to the brain. The brain is a glutton for oxygen, so even a slight lack of circulation can affect its performance immediately and over time. Additionally, excess saturated fat can increase the risk of heart disease and type 2 diabetes, which further raise one’s risk of dementia. While the body certainly needs some saturated fat to stay healthy, scientists agree that as far as the brain is concerned the less saturated fat, the better.
You should also avoid trans fat, which is the worst type of fat you can ingest. Trans fats are dangerous to your overall health and well-being, and recent research has found an association between trans fats and an increased risk of cognitive decline and dementia. It takes very little trans fat in the diet to develop cognitive impairment. Across several studies, people who consumed two grams a day of trans fats had twice the risk of those who ate less than two grams. Furthermore, most people in those studies ate at least two grams a day, with the majority of participants eating more than double that on a regular basis.
Typical processed foods that are high in trans fats include baked goods, like commercial doughnuts, cakes, piecrusts, biscuits, and frozen pizza; many snack foods, such as cookies and crackers; margarines (stick or spread); and commercial cheeses, along with many other spreadable or creamy products. The more packaged and processed foods you consume, the more hidden trans fats and artificial substances you may be consuming, and the higher your risk of negative outcomes. I recommend taking a careful look at the ingredient list on the food packages you pick up and steering clear of the following:
hydrogenated fats (like the ones mentioned above)
partially hydrogenated fats (also called PHO)
DATEM (an emulsifier used in baking to create a gluten network in dough)
mono- and diglycerides
Finally, diets high in saturated and trans fats, plus copper, particularly from supplements, may be associated with particularly quick rates of cognitive decline.
How much of an impact can diet have on avoiding and reversing cognitive decline?
We need more research to quantify the impact of diet in preventing cognitive decline and dementia, but there is evidence that healthy strategies to fight dementia—including diet, exercise, intellectual stimulation, and vascular risk management—are successful in improving cognitive performance in older adults.
In these studies with at-risk elderly participants, the participants showed a 25 percent improvement in cognitive performance in just two years. The program was particularly effective at boosting people’s ability to carry out complex tasks, like remembering phone numbers and running errands efficiently, which improved by 83 percent. Even better, the speed at which they were able to conduct these tasks improved by as much as 150 percent.
The brain is living tissue; it can be damaged through diet, and it can also be healed through diet. While the field of neuronutrition is too young to speak with conclusive certainty, the early research provides good news for those who adopt a brain-healthy diet.
Which herbs and supplements are best for brain health?
There are a variety of things that may be beneficial for your brain health:
Turmeric is a spice commonly used to make curry, and it has been used for at least 5,000 years in Ayurvedic medicine for many types of pain and inflammation associated with aging. Recent evidence shows that this spice—or more specifically, its active ingredient, curcumin, may help protect against cognitive loss and dementia by keeping our neurons healthy as we age.
Ginseng and ginkgo biloba are both herbs with anti-aging properties that may be helpful to improve cognitive function.
B vitamins, choline, vitamin B6, vitamin B12, and folate are helpful. Choline and vitamin B6 in particular are crucial for neuronal function. Choline is involved in memory processes, and vitamin B6 is involved in a little bit of everything.
Antioxidant vitamins (A, C, E) are excellent brain supplements. The brain is easily affected by oxidative stress and the action of free radicals. Antioxidants help the brain protect itself against the wear and tear that naturally occur with age and are also helpful to reduce risk of dementia.
What does your Alzheimer’s research tell us about women’s health?
Alzheimer’s disease affects more women than men: Two thirds of Alzheimer’s patients are women. Our studies show that transitioning into menopause increases the risk of Alzheimer’s in women. Symptoms like hot flashes, night sweats, and disturbed sleep originate in the brain. Recent research from our lab demonstrates that the ebb in estrogen causes the loss of a key neuroprotective element in the female brain, leading to a much higher vulnerability to brain aging and Alzheimer’s disease.
Our work has shown that for most of us, cognitive decline and dementia are not inevitable, determined by genetics or by age. Our brain health is affected by what we eat. That’s why my colleagues and I are doing our best to tell everyone what we should be feeding our brains so that we all can enjoy healthy, youthful brains for many years to come.
Lisa Mosconi, PhD, INHC, is the associate director of the Alzheimer’s Prevention Clinic at Weill Cornell Medical College in New York City and a founder and former director of the Nutrition and Brain Fitness Lab at NYU School of Medicine. She is the author of Brain Food: The Surprising Science of Eating for Cognitive Power and The XX Brain: The Groundbreaking Science Empowering Women to Maximize Cognitive Health and Prevent Alzheimer’s Disease. She received her PhD in neuroscience and nuclear medicine from the University of Florence, Italy, and holds a degree in nutrition sciences from the Institute of Integrative Medicine.
This article is for informational purposes only. It is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. To the extent that this article features the advice of physicians or medical practitioners, the views expressed are the views of the cited expert and do not necessarily represent the views of goop.
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