Find out what to eat and what not to.
“When it comes to diet, most people's concerns involve weight loss, fitness, cardiac health, cancer, and longevity. But what we eat affects more than our bodies; it also affects our brains”. - Dr Uma Naidoo, MD, Director of Nutritional and Lifestyle Psychiatry at Massachusetts General Hospital (MGH) & Director of Nutritional Psychiatry at MGH Academy
In today’s world, we are used to looking at food in terms of calories, in terms of macros (carbs, fats, protein), as energy for our activities of daily living, as processed or unprocessed, as traditional or modern, as non GMO or genetically modified, as organic or conventional and so on. But food is so much more. It is in fact, a major regulator that controls our health or disease status. Our genes respond to nutrition in a profound way. Genes can be turned on or off based on the food we eat through sophisticated mechanisms (epigenetic) that modify function at the DNA level.
Each time we eat, the type of food we eat, our consistency of physical activity, age and stress all come together with numerous genetic and environmental factors to affect our ability to utilize nutrients and optimize our brain function. This is true for our peripheral nerves as well where the intake of micro- and macronutrients have a synergistic effect on nerve function.
Another important connection between food and brain function lies within factors that affect the brain-gut connection, chief among which is the microbiome. Each of us is a unique individual in terms of genetics, in terms of the environmental influences we experience and just as important, the dietary milieu of our lives. We all interact with our environment on a daily basis, assimilate foods and utilize nutrients differently. What is appropriate and works best for me may not be appropriate for you and vice versa. The food we eat interacts with the trillions of bacteria, viruses and fungi that reside in our gut, called the gut microbiome.
The gut microbiome resides not only in the small and large intestines but also in the mouth, esophagus, pancreas, liver and in the gallbladder. The gut microbiome also regulates and influences cognitive function and dysfunction. Dietary habits can thus regulate the composition of the gut microbiome and in turn, our neurological health. In addition, after the brain, the gut contains the body’s largest number of neurons. This collection of neurons is called the enteric nervous system (ENS) and it manages gastrointestinal function independently of central nervous system (CNS) input. Because many neurotransmitters, signaling pathways and anatomical structures are common to the ENS and CNS, processes that are the basis of CNS disease often have gut manifestations. In short, nutrition modulates brain and nerve function throughout life.
Keeping these factors in mind, what we eat, when we eat and how we eat has profound implications for the health of our brain and nerves. Despite our unique identities, some general food rules are applicable for optimal brain health.
1. Picking the Right Fats
The fats in our diet can be divided into four general categories: monounsaturated, polyunsaturated, saturated and trans-fat. Saturated fat and trans-fat are associated with an increased risk of heart disease and other negative health consequences including neurological damage. Trans-fats are the worst type of fat for the heart, blood vessels, brain and the rest of the body because they raise bad LDL (a type of cholesterol) and lower good HDL, and create inflammation that has been implicated in heart disease, stroke, diabetes, and other chronic conditions. In fact, trans-fat can have harmful health effects even in small amounts – for each additional 2% of calories from trans-fat consumed daily, the risk of coronary heart disease increases by a significant 23%.
On the other hand, polyunsaturated and monounsaturated fatty acids are associated with a decreased risk of heart disease as well as improved brain health.
Omega 3 fatty acids, which are a type of polyunsaturated fatty acid, have been studied for a variety of conditions, including its role in brain function, due to its anti-inflammatory properties. The body cannot make omega 3 fats so these must come from food. Omega-3 fatty acid deficiency has been associated with ADHD, dementia, and depression so it is no surprise that eating foods high in omega-3s can help improve cognition. One particular type of omega 3 fatty acid called DHA has been shown to play a role in nerve cell formation, as well as an important role in memory and learning. The best sources of DHA include salmon, bluefin tuna, sardines and herring. While fish is the main source of DHA, some plant foods also contain omega 3 fatty acids including flaxseed, chia seeds, walnuts and pumpkin seeds.
2. Balancing Your Omegas
Another type of polyunsaturated fatty acid, omega 6 fatty acids, has also been studied for their role in inflammation, heart health and brain health. There are several different types of omega-6 fatty acids and while some may possibly promote inflammation, other types have been shown to reduce inflammation. Recent research has shown that eating more omega-6 fatty acids did not increase inflammation and either reduced markers of inflammation or left them unchanged. This supports the notion that omega-6 fatty acids are not only safe, but they could also be beneficial for circulation and easing inflammation which can in turn promote brain health.
Both omega-6 and omega-3 fatty acids influence gene expression making the need of balanced dietary intake essential for health and disease prevention.
It is best to get our omega-6 fatty acids from plant sources like safflower oil, sunflower oil, olive oil and nuts and seeds like walnuts, sunflower and pumpkin seeds. The unhealthy and harmful omega-6 fatty acids found in processed foods like chips, fries and baked goods should be avoided as much as possible since these usually also contain high amounts of saturated and/or trans fats as well.
On average, most Americans eat more omega-6 fats than omega-3 fats, about 10 times more. A low intake of omega-3 fats is not good for heart or brain health, so bringing the two into better balance is a good idea. To improve the ratio of omega-3 fats to omega-6 fats, eat more omega-3s not fewer omega-6. Overall, it is recommended that saturated fats generally should not make up more than 6-7% of your total calories each day while unsaturated fats (poly and monounsaturated) should not make up about 20% of your total calories.
3. Eating the Rainbow
Eating a rainbow of plant foods ensures you’ll get a wide variety of antioxidants, vitamins, minerals and phytonutrients essential for promoting brain health. Research has shown that cruciferous vegetables contain beneficial plant compounds known as phytochemicals that can reduce inflammation and improve blood flow to the brain. Cruciferous veggies that boost cognition are broccoli, cauliflower, cabbage, kale, bok choy, arugula, brussels sprouts, collards, watercress and radishes.
In addition to cruciferous vegetables, consuming fruits high in an antioxidant called anthocyanin has been shown to protect brain cells from damage done by harmful free radicals. Some fruits high in anthocyanins include blueberries, strawberries, raspberries, cranberries, grapes and cherries. You can reap the benefits by using either fresh, frozen or dried berries and cherries.
4. Going Nutty
Nuts contain the antioxidants vitamin E and selenium and have been shown to protect the brain from oxidative stress. We know that serum selenium concentrations can decline with age and may be associated with decline in brain function due to decreases in selenium’s antioxidant activity. Brazil nuts are one of the richest sources of selenium and just one Brazil nut supplies all the selenium you need in a day!
5. Staying Hydrated
Even mild dehydration can cause reduced concentration/alertness, slower reaction times and decreased cognitive abilities. For most people, 8-10 cups of water per day will meet fluid needs, but if you are on active chemotherapy you will likely need additional fluids to help flush out your system. You may also need more fluid if you exercise regularly, work outside or live in a hot climate. A good indicator to gauge your hydration status is your urine color. If your urine is dark and has a strong odor you’re most likely dehydrated and should increase your fluids. If your urine is completely clear you’re likely drinking too much. Aim for a pale-yellow color.
6. Adding Fiber
Dietary fiber consists of complex carbohydrates, which are neither digested nor absorbed but instead fermented in the gastrointestinal tract. Unlike other macronutrients such as fats, proteins or carbohydrates that are digested and absorbed, fiber is not digested by your body. Instead, it passes relatively unaltered through the stomach, small and large bowel and out of the body. Fiber is classified as:
- Soluble fiber, which dissolves in water to form a gel-like material. It can help lower blood cholesterol and glucose levels. Soluble fiber is found in oats, peas, beans, apples, citrus fruits, carrots, barley and psyllium.
- Insoluble fiber, which helps food move through the digestive system, promoting regularity and helping prevent constipation. Wheat bran, nuts, beans and vegetables, such as cauliflower, green beans and potatoes, are good sources of insoluble fiber.
The dietary fiber shapes the gut microbiome and impacts levels of fermented end products, such as short-chain fatty acids (SCFAs). There are three types of SCFAs; acetate, propionate and butyrate. New research suggests soluble fiber regulates the composition of gut bacteria. This composition may affect neuroinflammation, which plays a role in the onset of dementia. Reduced brain inflammation is linked to less cognitive decline and lower risk of dementia with age. These short chain fatty acids have been studied and shown to manipulate the epigenome to delay brain aging in various ways. High fiber foods include resistant starches (e.g., whole grain and legumes) and fructo-oligosaccharides (FOS) (e.g., bananas, onions, and asparagus) that enable butyrate-producing bacteria to thrive. These high fiber foods can help with optimal brain-gut interactions and consequently improve brain function. As always, talk to your cancer care team before changing your diet, especially if you have other treatment-related complications such as diarrhea or constipation.
7. Choosing Vitamin D
Vitamin D is a neuro-steroid that has been shown to protect against depression and anxiety. It helps to reduce inflammation and the effects of oxidative stress on the brain. It affects not only the function of individual brain cells but also the integrated function of the brain as a whole.
Vitamin D is found in three places: the sun, from foods and supplements. The sun's ultraviolet B (UVB) rays interact with a protein called 7-DHC in the skin, converting it into vitamin D3, the active form of vitamin D. Foods such as fatty fish, milk, and eggs either contain vitamin D naturally or are fortified with it. A supplement that contains 600 IU/day (600 IU vitamin D is 15 mcg) can help maintain optimal levels of Vitamin D. Walking in the morning sun for about 15 minutes each day ( 2-3 days a week) can help you get the right amount of Vitamin D. It is best to get your vitamin D status tested and talk to your physician before starting any supplements.
8. Eating at Regular Intervals
While this seems like common sense, not skipping meals can make a big impact on our focus and concentration. Not eating at regular intervals can result in not consuming enough calories and that can lead to feeling “foggy”, tired and having low energy. It is a good idea to eat wholesome meals with balanced macronutrients (carbs, fats, proteins) to help keep blood sugar levels steady and to provide energy to help fuel a healthy metabolism. As a bonus, eating at regular intervals also prevents between-meal hunger that can lead to overeating at meals.
Coping with chemo brain or peripheral neuropathy may require a variety of different strategies but diet is definitely an important and proven strategy to help with these side effects of cancer treatment. Eating right and at right times during the day can contribute to boosting your brain and nerve health.