Nutrition and The Brain

What Role Does Nutrition Play in our Cognitive Function, Focus, Memory, Attention, and Alertness, and How to Reduce Brain Fog as well as the Risk of Neurodegenerative Diseases like Alzheimer’s and Parkinson’s Disease

Nutrition and the Brain: Neurodegenerative diseases happen when nerve cells in the brain deteriorate and die. Neurodegenerative diseases include Alzheimer’s disease Parkinson’s disease, amyotrophic lateral  sclerosis (ALS), and Huntington’s disease.

In this article, we are going to look at not only what the research says about the role nutrition plays in neurodegenerative disease, but also what role nutrition plays in general cognitive function, focus, attention, memory, and alertness.

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Reducing the Risk with Lifestyle

There are many factors that appear beneficial in preventing cognitive decline in older adults. In fact, when researchers looked at 1,260 older adults at risk for Alzheimer’s, they found that physical activity, diet, cognitive training, social activities, and management of heart disease and blood pressure improved cognitive performance in older adults.

While all of these lifestyle factors are important, we are focusing on diet for this article. Overall, reducing the inflammation and oxidative stress in the brain appears to significantly reduce the risk or slow the progression of neurodegenerative disease. Many of the nutrients and foods discussed below help with neurodegenerative diseases in this way.

Nutrition and the Brain: General Diet

You can’t talk about the best overall diets for Alzheimer’s and Dementia without talking about the MIND and Mediterranean diets. According to extensive research, including a systemic review, the MIND and Mediterranean diets, which are similar diets, are shown to decrease the risk of developing Alzheimer’s and Dementia as well as slowed the rates of cognitive decline  (1, 6, 7, 8, 10, 54). These diets are also linked to improved cognitive function in the general population as well.

Both of these heavily plant-based diets recommend a high fruit and vegetable consumption along with cold water fish, olive oil nuts, seeds, legumes, and grains.

The MIND Diet

The MIND diet mostly consist of vegetables, especially leafy greens; nuts, berries, beans, whole grains, fish, poultry, olive oil and wine. The Mind diet recommends greatly limiting red meat, butter/margarine, cheese, sweets and fried or fast food.

The main difference in the MIND and Mediterranean diet is that the MIND recommends that most of your fruit consumption come from berries.

The Prudent Diet

The Prudent diet, which is similar to the Mediterranean and MIND diets, has also been shown to reduce cognitive decline. A total of 2223 dementia-free participants over 60 were followed up for 6 years to examine the impact of dietary patterns on cognitive decline. The prudent diet appeared to reduce cognitive decline compared to the western diet. The Prudent diet consists of fruits, vegetables, whole grains, legumes, nuts, fish, and low-fat dairy products. With the Prudent diet, you also limit consumption of refined or processed foods, red meats, high concentrated sweets, eggs, and butter. The western diet is known for being high in ultra-processed foods, sugar, refined carbohydrates, fried foods, and low in fruit and vegetables.

Another study found that people 65 years old or older who regularly ate nuts, fish, tomatoes, poultry, cruciferous vegetables, dark, leafy vegetables, and fruits while limiting their consumption of high fat dairy, red meats, organ meats, and butter significantly lowered their risk of developing Alzheimer’s.  

The Western Diet and The Brain

Epidemiological studies and mice studies have also shown that high intakes of trans fat, saturated fat, salt, and sugar adversely affect cognition (22). Cognitive performance declines in individuals who have a diet heavy in these food ingredients. According to a meta-analysis, there was a moderately elevated risk of Parkinson’s disease among individuals with high dairy consumption as well (59,

One  explanation for the positive association between dairy and Parkinson’s disease may involve the effects of dairy on uric acid levels. Uric acid may be neuroprotective. Higher plasma uric acid levels have been associated with a lower risk of incident Parkinson’s disease in two studies (59.) After someone is diagnosed with Parkinson’s disease, dairy consumption is often reduced to decrease uric acid.

What Others Say about Nutrition and the Brain

According to Marilyn Haugen and Doug Cook, RD in 175 Best Super food Blends Recipes, “A diet rich in fruits, vegetables, nuts, seeds, legumes, whole grains, fish, antioxidants, and healthy herbs and spices can reduce the risk of Type 2 Diabetes by 90% and Alzheimer’s by 40%.”

Maggie Mood states in The MIND Diet that the two key MIND diet studies show how the diet keeps the aging brain seven and a half years younger and reduces the risk of developing Alzheimer’s Disease by 53%.”

Nutrients and The Brain

According to a critical review as well as other studies, the evidence is “fairly strong” for the protective quality of Vitamin E, Omega-3, DHA, Vitamin B12, and folate in regards to cognitive function. Vitamin D, iron,  iodine and antioxidants like vitamins C, vitamin A, zinc, selenium, lutein and zeaxanthin may exert neuroprotective effects and improve cognitive performance as well (21). All of these nutrients are found in the foods recommended in the Mediterranean and MIND diets (19, 21).

I cannot emphasize enough that study after study shows that the MIND or Mediterranean-style diet appears to reduce the risk of developing Alzheimer’s and dementia as well as general cognitive decline.

You can learn more about these brain foods and HOW to get them into your diet in The Nourishing Meal Builder.

Nutrition and The Brain: Cognitive Function in Children

We have talked about how the quality of the overall diet can effect cognitive decline, reduce the risk and slow the progression of Alzheimer’s and dementia in older adults. We have even touched on the fact that the quality of the diet improved the cognitive function in the general population. But what does the research say about the role diet plays in the cognitive function of children? According to a study in the Journal of American College of Nutrition, when researchers looked at the breakfast composition of 689 students in Kansas, researchers found that non-breakfast consumers had significantly lower test scores on the WAIT-III. In addition, breakfast consuming children who ate whole grains had significantly higher scores in reading, fluency, and math compared to children who drank fruit juice (9).

Research also looked at 396 children in Australia and 394 children in Indonesia ages 6 to 12. These children received a drink containing iron, zinc, folate, vitamin A, Vitamin B6, vitamin B12, Vitamin C, and Omega-3s. Results showed higher scores on tests that measured memory and verbal intelligence in both boys and girls in Australia, but only girls in Indonesia (21).

Nutrition and The Brain: Other Diets

Intermittent Fasting

It should also be noted that some preliminary research suggest that calorie restriction and intermittent fasting may be beneficial in some neurodegenerative diseases like Alzheimer’s and Parkinson’s Disease (43).

Also, current research has linked obesity to an increased risk for Alzheimer’s and Parkinson’s Disease (50,51).

Excessive Calories

Moreover, excessive calories may have a negative effect. In mice studies, reducing calories by 40% decreased deficits in motor and cognitive function associated with aging (21).

Since the Mediterranean, MIND, calorie restrictive, and intermittent diets promote weight loss, these diets may help reduce the risk of developing some neurological diseases by helping with weight loss as well.

Low Glycemic Index Foods

Low glycemic index foods seem to improve attention and memory. The glycemic index is a measure of how quickly a food causes our blood sugar to rise. Usually foods that rank high on the glycemic index are highly processed carbohydrates and sugars.

The Keto Diet

Although more evidence points to the benefits of the MIND and Mediterranean diet when it comes to reducing the risk of neurodegenerative diseases like Alzheimer’s as well as promoting general cognitive function, some studies have found benefits from the Keto diet as well, especially in Alzheimer’s and Parkinson’s disease.  A few studies indicate that the keto diet, which is a diet low in carbohydrates and higher in fats, may be neuroprotective and help reduce symptoms of Alzheimer’s and Parkinson’s (53, 54). Most of the studies are in vivo or in vitro; however, there have been a few human studies. These studies demonstrate a reduction of disease symptoms when patients started the Keto diet. The researchers cautioned implementing this diet with elderly patients due to a greater risk of malnutrition, and research still needs to be done on the long-term effects of the keto diet.

So how do we reconcile the research that says the Mediterranean and MIND style diets are beneficial AND the keto diet is beneficial?

One reason the keto diet may be protective against neurodegenerative diseases is the fact that many lose weight on the keto diet. Another benefit of the keto diet may come from it’s “fasting-like” effects on the body. However, you can get these effects from the Intermittent fasting method as well. The keto diet is also like the MIND and Mediterranean in the fact that all of these diets recommend limiting refined carbohydrates like white bread, sugar, pastries, and soda. It is recommended that the fats you eat on the keto diet come from mostly healthy fats like cold water fish, avocados, grass-fed meat, nuts, seeds, and olive oil.  The keto diet also recommends eating lots of low carb vegetables like dark leafy greens. This is in sync with the Mediterranean and MIND diet as well.

There are some foods shown to reduce the risk of cognitive decline that are limited when someone is on the keto diet. These include fruits (although berries are allowed in moderation) and probiotic-rich yogurt.

So What Does This Mean? Which Diets Should We Follow?

If you are interested in following some aspects of the keto diet, then perhaps a combination of these diets could be followed in order to include the beneficial aspects of the keto diet as well as the MIND and Mediterranean diets. For example, someone could focus on eating  a diet full of the vegetables and healthy fats (which are also part of the keto diet and Mediterranean diet), but also include fruits, especially berries, which is recommended when someone is on the Mediterranean diet. As for carbohydrates, many people are overeating carbohydrates. So although there are a multitude of benefits to including healthy carbohydrates in our diets, we should avoid overeating them.  If someone wanted the fasting-like benefits of the keto diet, then perhaps they could try intermittent fasting. However, intermittent fasting and the keto diet are sometimes hard to sustain for some and are not recommended for someone at risk for disordered eating.

Nutrition and the Brain: Individual Nutrients

Nutrition and the Brain: Omega-3

Omega-3, especially DHA Omega-3, appears to help prevent cognitive decline and  promote cognitive function and thinking abilities according to both animal and human studies (1, 21, 22, 23). Studies on mice have shown Omega-3 consumption decreased beta-amyloid plagues in the brain, which is a distinctive feature of Alzheimer’s. In a study of 485 older adults with age-related cognitive decline, those that took DHA omega-3 for 24 weeks showed improved learning and memory compared to the placebo (1). However, a small number of similar studies showed no effect in older-adults with cognitive decline.

Omega-3 and Cognitive Function in Students

 Other studies have shown improvements in reading, spelling, teacher-rated behavior, and school performance in groups of students receiving Omega-3 versus the placebo(21). This would indicate that not only does Omega-3 have the potential for reducing the risk of developing Alzheimer’s, but also has the potential for improved general cognitive function, focus, and attention.

Just getting Omega-3 is not the only factor, however. It appears that the ratio of Omega-3 to Omega-6 in the body is also important. A 5:3 ratio of Omega-3 to Omega-6 has been associated with better memory and lower risk of cognitive deterioration 21. In the United States, we are getting more omega-6 compared to Omega-3. In other words, we are getting too much omega-6 and not enough Omega-3s.

Recent research has strongly indicated that Omega-3 may even be beneficial in treating traumatic brain injuries (52). However most of the evidence comes from rat studies. A few human studies have suggested that Omega-3 supplementation may be helpful in the recovery of Traumatic Brain Injury (53).

Omega-3s as well as vitamins appear to be more effective when eaten in food than when taken as a supplement (54).

Folate

Folate deficiency can lead to neurological disorders, depression, and cognitive impairment. Supplements have been shown to prevent cognitive decline and dementia during aging (21, 22).

Alpha lipoic acid

Alpha lipoic acid has been shown to improve memory deficits in animals with Alzheimer’s and decrease cognitive decay in a small group of patients with Alzheimer’s (21). Spinach, broccoli, tomatoes, and Brussel sprouts are good sources of Alpha lipoic acid.

Nutrition and the Brain: Gut Health

It appears that gut microbiome balance may influence the onset and progression of Alzheimer’s disease, as well as promote cognitive function. To be in balance, we want our gut to have plenty of good bacteria (ie probiotics). We also want to make sure our gut does not have too much of the bad bacteria. Imbalances in the gut can lead to inflammation and oxidative stress, which can increase the neuroinflammatory risk associated with cognitive decline. Studies in mice and humans show that animals and humans with mild cognitive impairment have a different gut microbiome make-up than that of non-cognitive impaired individuals (1, 12). Several rat studies have shown an increase in cognitive function and memory in rats given probiotics. In one study, lead-exposed rats were given probiotics to restore their gut microbiome. The researchers found that after the rats were give probiotics, their memory was repaired (61).  

Human studies have suggested that probiotics could benefit Alzheimer’s patients as well as promote general cognitive function, focus, and attention (11, 12, 13, 14, 15, 16, 38). In a randomized, double-blinded controlled trial, probiotics improved cognitive function in patients with Alzheimer’s disease (37).

Gut Health and ALS

Although more research is needed, early research including a systemic review suggests that gut microbiome dysbiosis may contribute to ALS onset and progression; therefore, eating probiotic and pre-biotic-rich foods may be beneficial (40, 41). It should also be noted that the gut microbiome appears to be different in ALS patients (42).

Gut Health and Parkinson’s Disease

In vitro evidence suggest probiotics may decrease oxidative stress, inflammation, and bacterial overgrowth in individuals with Parkinson’s disease (60). The most beneficial strains seem to be L. salvarius and L. acidophilus.

Gut Health: The Take Home Message

Based on preliminary research microbiome imbalance could be a trigger for neurological disorders; therefore, incorporating probiotic-rich foods may be beneficial.

Nutrition and The Brain: Specific Foods

Nutrition and the Brain: Antioxidant-Rich Foods: Fruits, Vegetables, Dark Chocolate, and Green Tea

Antioxidant consumption is linked to improved cognitive function and reduced risk of Alzheimer’s disease and other neurodegenerative diseases. Positive links have been found in the antioxidants like vitamin E, vitamins C, vitamin A, zinc, selenium, lutein, zeaxanthin, polyphenols, flavonoids, catechins, resveratrol, and quercetin (28). Foods rich in antioxidants have also been shown to be neuroprotective. Antioxidant-rich foods appear to reduce the risk of Alzheimer’s, dementia, and may help with cognitive function of the general population. These foods include fruits, especially berries; vegetables, especially cruciferous vegetables and dark leafy greens; and dark chocolate (23).

A 3-year cohort study found that lower intakes of vegetables and legumes were associated with cognitive decline among illiterate elderly (4). Also when researchers looked at  4,740 individuals 65 or older, researcher found that a combination of vitamin C and vitamin E supplementation was linked to a 78% reduction in the prevalence of Alzheimer’s Disease (44, 45). Moreover, high serum levels of B-carotene was associated with an 85% reduction in the risk of cognitive decline in older adults (46).

Antioxidants and ALS

According to 5 cohort studies, diets high in antioxidant, vitamin E, carotene, and lutein like fruits and vegetable, especially dark leafy greens has been linked to a decrease risk of developing ALS (39). However, taking vitamin C supplements (vs eating carotene-rich food) appeared to slow ALS progression but did not stop the onset.

Vitamin E

Vitamin E, an antioxidant found in foods like leafy greens and nuts, may improve cognitive function (21). Decreased levels of vitamin E is associated with poor memory in older adults. Moreover, in aging mice, vitamin E has been shown to extend lifespans and improve mitochondria function and neurological performance (21).

Quercetin

In mice studies quercetin, which is an antioxidant, reduced learning and memory impairment

(21).

NAC, Selenium, and Glutathione

Selenium, NAC, and Glutathione are all antioxidants that, according to experimental studies, may protect against Parkinson’s Disease (55).

Dark Leafy Greens

One study found that dark leafy greens such as spinach and kale were associated with slower age-related cognitive decline. Healthy older women who consumed a combination of lutein and DHA everyday had improved verbal fluency, memory scores, and increased rates of learning after 4 months (61). Lutein is found in dark, leafy greens and DHA is found in salmon, tuna, and other fatty fish.

Berries

Dietary intakes of berries and flavonoids appears to reduce rates of cognitive decline in older adults based on a study in Annals of Neurology (5).

According to research, men who regularly consumed flavonoid-rich foods like raspberries and blueberries were 40% less likely to develop Parkinson’s disease (57).

Moreover, when older adults ate 1 cup of blueberries for 90 days, their memory and their ability to accurately switch tasks improved compared to the placebo (58, 59)).

Nuts and Seeds

Tree nuts are a good source of vitamin E, folate, fiber, antioxidants, and Omega-3s. All of these nutrients appear beneficial when it comes to decreasing oxidative stress, decreasing inflammation, and improving cognitive function (20). Types of tree nuts include walnuts, Brazil nuts, almonds, pistachios, and pecans. Walnuts are especially helpful when it comes to the brain. Walnuts are the best nut source of Omega-3s and also contain melatonin. Melatonin deficiency has been linked to degradation of cholinergic neurons in the basal forebrain and the deposition of aggregated proteins in the brain. This could lead to cognitive impairment and depression (20). Although we are not sure if this is a major player when it comes to walnuts benefits to the brain, evidence does show that regularly eating walnuts is linked to better cognitive function (20).

Fava Beans

Although the research is limited, some small studies suggests that Levodopa found in broad beans (also called fava beans) may slow the progression or relieve symptoms of Parkinson’s Disease (58). But if you have Parkinson’s disease, it is important to talk with your doctor before eating Fava beans in excess. You could overdo it, if you are taking medications and eating Levodopa-rich foods. This excess could cause dyskinesia in people with Parkinson’s. You should continue to take medications per your doctors’ recommendations.

Pomegranate Juice

A study found that pomegranate juice increased memory and improved functional MRI activity in older adults with mild memory complaints (3).

Foods that Contain Nicotine

Some studies suggest that nicotine may provide some protection against Parkinson’s Disease; however, the cost of smoking far outweighs the benefits. You can get nicotine from foods like peppers and tomatoes. One study even found that people who regularly ate nicotine-rich foods, where less likely to develop Parkinson’s’ Disease (56). In fact, one study even found that pepper consumptions was inversely associated with Parkinson’s’ disease.

Coffee and Caffeine

Coffee may improve general concentration and focus; reduce the risk of cognitive decline; and reduce the risk of developing Parkinson’s and Alzheimer’s as well as improve general concentration and focus (24, 25, 26, 27, 35). In one study, patients with Parkinson’s Disease found their symptoms improved after taking caffeine pills. Caffeine found in coffee may also reduce the risk of Parkinson’s disease as well (55).

Turmeric

According to some research, turmeric may improve cognitive function (21). Turmeric has been shown to reduce memory deficits and cognitive decline in animal models of Alzheimer’s and brain trauma. It has also been noted that there is a low prevalence of Alzheimer’s in India where there is a high consumption of turmeric (21).

Rosemary

Rosemary may protect the brain against aging, protect against neurodegenerative diseases like Alzheimer’s, and may even help with concentration and cognitive performance. In a randomized double-blinded, placebo-controlled clinical trials, rosemary appeared to significantly increase speed of memory in the elderly  (105, 106, 107). Rosemary may also support recovery from conditions that lead to brain damage (i.e. strokes) and may protect the brain against aging (107).

Sage

Both mice and human studies have demonstrated that several types of sages may positively impact cognitive function and protect against neurodegenerative diseases (109). According to studies, Sage may improve learning, memory, and information processing in people with mild to moderate Alzheimer’s. In a double-blinded randomized placebo-controlled trial, participants with Alzheimer’s who consumed common sage performed better on tests that measured memory, problem solving, reasoning, and other cognitive abilities better than the group taking the placebo (108). Another study found that Spanish sage improved alertness and cognitive performance in healthy young volunteers (107).

Nutrition and the Brain: Supplements

A Note on Food vs. Supplements

Some of the studies discussed in this post looked at the benefits of taking a nutrient in the form of a supplement. While I take an optimistic approach with food and their benefits, I am more cautious with supplements for two reasons. One, they can be expensive, and two, we can take too much and become toxic. Some supplements can negatively interact with medications. Always talk with your doctor before taking supplements.

In the case of food, however, even if the research is preliminary and conflicting as far as a particular benefit; if the food is generally healthy, why not incorporate it in our diets? 

Ginseng

Although some of the evidence is weak, early research suggest that ginseng may improve mental and physical performance (29, 30, 34, 35). Other studies show that when patients with Alzheimer’s took Ginseng long-term, their cognitive deficits improved (31, 32, 33, 36).

Ginkgo

According to a systemic review and meta-analysis, ginkgo may slightly improve cognitive function in individuals with dementia (10).

Ashwagandha

A few preliminary studies show that Ashwagandha may improve memory and cognitive function. One randomized-controlled study found that Ashwagandha improved memory in people with mild cognitive impairment (2).

Coenzyme Q10

A study in the Archives of Neurology found that in 80 participant with Parkinson’s Disease, coenzyme Q10 appeared to slow the progressive deterioration of Parkinson’s Disease compared to the placebo group (47). Other studies have had conflicting results. Coenzyme Q10 may be more beneficial in people with a deficiency; however, a coenzyme Q10 deficiency is rare (48).

CBD

Early research shows that taking CBD daily for 4 weeks may improve psychotic symptoms of Parkinson’s disease (49).

Exercise

Exercise has been shown to enhance learning and memory, counteract mental decline, and even enhance mental capacity in young adults. Physical activity has even been shown to help with cognitive recovery after a brain injury. Exercise in combination with Omega-3 and Flavonoids may be the most beneficial (21).

Nutrition and the Brian

What to Eat Cognitive Function, Focus, Attention, and Alertness and What to Eat to reduce the risk of neurodegenerative Disease like Alzheimer’s and Parkinson’s : A quick guide

1. Eat a Mediterranean/MIND-Style Diet.
   1. Diet should be mostly plant-based whole foods and consist of antioxidant and Omega-3-rich foods.
   2. Include vegetables, especially leafy greens, nuts, seeds, fruits, especially berries, beans, while grains, fish, poultry, olive oil, green team and dark chocolate.
2. Limit refined carbohydrates and sugars, ultra-processed foods, processed meats, and fried foods. Consider limiting high fat dairy.
3. Incorporate probiotics and prebiotics into your diet.
4. Add Turmeric, Rosemary, and Sage to some of your meals.
5. Consider regularly consuming caffeine containing drinks and nicotine containing foods like peppers and tomatoes.
6. Talk with your doctor before adding supplements. Supplements that show promise include Ginseng, Ginkgo, and Ashwagandha.
7. Although there is strong evidence that the Mediterranean and MIND diets promote cognitive function and reduce the risk of Alzheimer’s and other neurodegenerative diseases, some evidence indicates that the keto diet and intermittent fasting may be beneficial as well. Consider incorporating the beneficial aspects of these diets.

Want to Learn more about Nutrition and the Brain?

Lacy Ngo, MS, RDN is the author or The Nourishing Meal Builder and The Nourishing Meal Builder: the Gluten-Free, Dairy-Free Edition. In the Nourishing Meal Builder books, you will get:

• An evidence-based list of foods that boost mood; promote cognitive function, focus, attention, alertness, and memory; support the immune system; aid in weight loss; reduce the risk of chronic diseases, autoimmune diseases, Alzheimer’s disease, joint pain, and even seasonal allergies.
• A simple meal plan checklist that will help you eat balanced meals on a daily basis that fuels your mind, body, and spirit.
• A faith-based mindfulness and mindful eating guide.
• Printable Meal Builder cards.

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