5.2 Plan Nutritional Strategies to Impact Neurologic Wellness

Blood Glucose

Control of blood glucose is a key aspect of brain health. High blood glucose levels are associated with accelerated cognitive decline compared with individuals who maintain normal blood glucose levels, independent of a diagnosis of diabetes. High blood glucose is more common among individuals with excessive body fat because fat releases hormones, proteins, and cytokines that ignite inflammation in the body, worsening brain function. Refined sugars are highly processed, often derived from white sugar, brown sugar, coconut sugar, palm sugar, or high-fructose corn syrup, and most Americans consume about 163 g (652 calories) of refined sugars each day. Refined sugars contained in candies, baked goods, pastries, white bread, crackers, pasta, and white rice contain no nutrients and can dramatically raise blood glucose. Therefore, foods containing processed sugar and other processed ingredients should be limited or eliminated from the diet to ensure optimal long-term cognitive performance.

The dietary recommendations for neurologic health largely mirror those of the American Heart Association for heart health. A normal blood glucose level after a period of fasting is generally between 70–100 mg/dL. An elevated level (100–125 mg/dL) can indicate prediabetes, with higher levels (greater than 125 mg/dL) signaling a possible diagnosis of diabetes. Blood glucose trends over a period of 2–3 months can be evaluated using the hemoglobin A1c (HbA1c) test. The normal range for HbA1c is less than 6%, and 6.0–6.4% is considered prediabetes. A person is considered to have diabetes if the HbA1c is 6.5% or greater.

A ketogenic diet has been shown to be beneficial for people with epilepsy (Kossoff, 2017). A ketogenic diet contains a high percentage of fat and few carbohydrates and has been successfully used in children with seizures that are intractable with medications alone. In this diet, ketones are formed as the body uses fat for energy rather than carbohydrates. Although there are many theories regarding why this type of diet is beneficial for individuals with seizures, the high levels of ketones in conjunction with antiseizure medications appear to increase the seizure threshold, resulting in fewer seizures (Kossoff, 2017).

Complex carbohydrates contain more nutrients than simple refined sugars do. They are found in brown rice, oats, quinoa, farro, barley, fruits, and vegetables, and they also contain more fiber, which slows the rise in blood glucose. However, in the absence of a diabetes diagnosis, small doses of natural sugars (honey, maple syrup, or stevia) are generally well tolerated and do not have a significant effect on brain function. Artificial sugars (such as aspartame, saccharin, and sucralose) are not recommended for brain health because they affect the gut microbiome, leading to insulin resistance and diabetes, and subsequently have been shown to contribute to decline in cognitive function (Pase et al., 2017).

Sodium

Disruptions in sodium balance are a concern for clients with neurologic conditions, especially when they are critically ill. The balance of water in the body is monitored by the osmoreceptors in the hypothalamus, as well as by baroreceptors in the right atrium, great veins, and carotid sinus. The total water volume in the body is controlled by regulation of sodium by the kidneys. Any change in sodium and water balance can dramatically affect the cells of the brain. Sodium levels may be disrupted due to various conditions such as renal dysfunction, cirrhosis, lung disease, certain cancers, congestive heart failure, diarrhea, vomiting, blood loss, or excessive sweating or can be the result of diuretic medications. Neurospecific conditions, such as subarachnoid hemorrhage, TBI, meningitis, encephalitis, and brain tumors, can disrupt sodium balance and result in hyponatremia, a serum sodium level less than 135 mEq/L, which can cause various neurologic symptoms. Such disruptions are sometimes caused by failure in the brain to release antidiuretic hormone (ADH), as is the case in central diabetes insipidus, or by urinary sodium loss without water loss, as is the case in syndrome of inappropriate antidiuretic hormone secretion (SIADH). SIADH is caused by an unsuppressed release of ADH from the pituitary gland or other nonpituitary sources that signals the body to retain fluid (Yasir & Mechanic, 2023). Therefore, nurses should evaluate the sodium and water balance of all clients with neurologic conditions as a routine part of the nutritional assessment.

Omega-3 Fatty Acids

Omega-3 fatty acids are specific unsaturated fatty acids that are often referred to as “good fats” because they have a significant positive impact on brain function. However, many Americans consume a disproportionate quantity of omega-6 fatty acids, found in corn and vegetable oils in processed foods. Although not routinely tested for, the omega-3 index is a measure of the percentage of certain fatty acids in the red blood cell membranes: eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The omega-3 index is an assessment of the percentage of total fatty acids in the body and is a marker that identifies cardiovascular and cerebrovascular risk for death (Swanson et al., 2012). An omega-3 index of less than 4% indicates a high risk for death, whereas a level greater than 8% represents a low risk for stroke or other cardioembolic events in the future (Swanson et al., 2012; von Schacky, 2020). Fatty fish, such as salmon, mackerel, and sardines, and wild meat, such as venison, buffalo, and other hunted game animals, contain omega-3 fatty acids. They are abundant in many plant sources as well, such as nuts, seeds (chia, pumpkin, sunflower), and flaxseed, olive, and canola oils.

Dietary Percentages of Carbohydrates, Fats, and Protein

The macronutrients (carbohydrates, fat, and protein) are the building blocks for optimal neurologic health. The recommended dietary allowance for carbohydrates is approximately 45–65% of a person’s daily calories, whereas protein should account for 10–35% of daily caloric intake, and fats should make up the remaining 20–35% of daily food intake (U.S. Department of Agriculture and U.S. Department of Health and Human Services, 2020).

For optimal brain health, current recommendations include daily intake of fresh vegetables, leafy green vegetables, berries, fish and other seafood, healthy fats (virgin olive oil, whole eggs, avocados), as well as nuts and seeds. Other foods that are recommended in moderate amounts are beans; legumes; whole fruits (in addition to berries); low-sugar, low-fat dairy products (plain yogurt and cottage cheese); poultry; and whole grains.

To prevent cognitive decline, fried foods, pastries, sugary and processed foods, red meats and meat products, and whole-fat dairy products (such as butter and full-fat cheese) should be limited or eliminated from the diet. Although margarine was once touted as a healthy alternative to butter because it contains no cholesterol, it may contain saturated fats, which have been shown to contribute to a decline in brain health. In one publication from the Nurses’ Health Study, replacing margarine or butter with the same quantity of olive oil resulted in a 5–7% lower risk for cardiovascular and coronary heart disease, both of which are risk factors for stroke (Guasch-Ferré et al., 2020).

The Mediterranean diet is well established to prevent or reduce cardiovascular- and age-related cognitive decline (Leight & Morris, 2020). It is low in saturated fat and plentiful in olive oil, legumes, broccoli, squash, whole grain cereals, fruits, vegetables, and fish. It includes moderate consumption of dairy products and wine and low consumption of nonfish meat products. The Mediterranean diet is recommended for neurologic health more than any other diet strategy and is particularly recommended for neurologic conditions, including multiple sclerosis, Alzheimer’s disease, and Parkinson’s disease (Leight & Morris, 2020).

An emphasis on fresh whole foods can also provide an effective path toward steady weight loss, as healthy eating habits are formed over time. Because the plan focuses on choosing fruits, vegetables, legumes, and snacks such as low-fat popcorn over potato chips, calorie-rich desserts, and other less healthy foods, and on choosing water over sugary drinks, this diet generally reduces the caloric intake.

The foods included in the Mediterranean diet are largely plant based and include healthy fats. Because the foods are filling, overall caloric intake generally decreases, although portion size remains a consideration if weight loss is desired. The fiber in the foods results in a diversity of gut bacteria, which is beneficial because a healthy gut microbiome has been shown to positively impact nutrient metabolism and energy expenditure. In some people, especially those with irritable bowel syndrome, bowel discomfort may result from the high fiber content in this diet. It is important to monitor potassium levels of clients with comorbid kidney disease because the Mediterranean diet is often rich in potassium.

For reasons still unknown, maintaining low glucose levels can help reduce the number of seizures in people with epilepsy. A ketogenic diet is sometimes recommended for these clients because it consists primarily of high-fat and high-protein foods and includes few carbohydrates. This causes a breakdown of fats, rather than glucose, for energy, which mimics a fasting state and has been shown to decrease seizure episodes. The ketogenic diet is commonly recommended for children with epilepsy and some adults. The diet is rich in butter, mayonnaise, and heavy cream; it includes small portions of fruit, cheese, and bacon, and other meats, fish, and poultry are allowed (Figure 5.5).

Figure 5.5 The macronutrients in the typical American diet compared with those in the Atkins diet, a classic ketogenic diet, and a therapeutic medium-chain triacylglycerides (MCT) ketogenic diet. The therapeutic ketogenic diet is typically prescribed for clients with epilepsy. (credit: “A series of pie charts depicting the calorific contributions from carbohydrate, protein and fat in four diets” by Colin, vectorized by Fvasconcellos (talk contribs)/Wikimedia Commons, Public Domain)

A modified Atkins diet is sometimes recommended for clients with epilepsy instead of a ketogenic diet. As with the ketogenic diet, the Atkins diet contains foods that are high in fat (bacon, eggs, beef, mayonnaise, butter, heavy cream, oil). Although some carbohydrates are allowed, the total amount of carbohydrates allowed is low (20–25 g/day).

Daily Eating Patterns

Many Americans do not follow a healthy diet, and studies show that adherence to healthy eating guidelines occurs only about 50–60% of the time across the lifespan (Wambogo et al., 2022). The appropriate amount of food to consume each day is based on a person’s age, sex, height, weight, and physical activity level. A calculator is available on the MyPlate website to assist in determining the appropriate number of calories that should be consumed to maintain normal weight, based on activity level. One successful strategy to reduce overall caloric intake among persons desiring to shed pounds is to use smaller plates.

The Difference Between Food and Supplements

Although many supplements are available over the counter, they are not meant to replace a healthy diet. Both the macronutrients and micronutrients that are found in food are easier for the body to absorb than supplements. Moreover, the variety of nutrients available in fresh foods has been shown to provide a higher nutritional value than consuming an unhealthy diet and taking supplements.

The Difference Between Thirst and Hunger

There is a strong link between hydration status and cognitive ability and mood. Water is the body’s principal component, making up 50–70% of total body weight (Tobias et al., 2022). The amount of daily water intake that the body requires varies by age, body size, activity level, and environmental temperature. It is recommended that most adults drink 6–8 8-oz glasses of water daily. The body loses water through urination, breathing, and sweating. However, as a person ages, the ability to distinguish thirst from hunger diminishes. Because of this, dehydration among older adults is a common problem. In many cases, by the time a person perceives thirst, moderate dehydration has already occurred, and cognitive abilities may be slowed. Moderate dehydration has been shown to cause headaches and can have a deleterious impact on mood, short-term memory, attention, focus, and numeric and psychomotor function.

Because many older adults are chronically dehydrated, moderate intake of coffee and tea, in addition to hydration from other liquids, can reduce cognitive decline and dementia because of the antioxidant effect of caffeine. However, caffeine intake should be limited because it can impact sleep, especially if consumed late in the day. Water is the best liquid to maintain hydration, and caffeinated liquids such as coffee and tea have a mild diuretic effect. Although caffeine increases diuresis, the amount of fluid in the drink is thought to balance this diuretic effect. Many people rely on drinking coffee or tea containing caffeine to increase alertness, as well as cognitive and athletic performance. According to the U.S. Food and Drug Administration (FDA), adults should consume no more than 400 mg of caffeine per day, and no intake of caffeine is recommended for children. Very high daily doses of caffeine (750 mg) have been linked to serious health conditions such as chest pain, irregular heartbeat, and stroke, as well as problems with sleep, loose stools, and gastrointestinal upset. The long-term effect of caffeine intake is not well understood.

Alcohol is not a source of hydration but can have both positive and negative impact on brain function; however, deleterious effects on brain function are more commonly reported for individuals consuming excessive amounts of alcohol (Grant et al., 2017). Moderation in alcohol intake may be the key to optimal brain health. Current recommendations cite safe alcohol use as only 1 drink/day for men and women. The type of alcohol intake may also be considered. Red wine contains polyphenols, micronutrients that can positively impact blood pressure, and 1 glass/day may reduce stroke risk (Grant et al., 2017).