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Nutrition for Nurses

6.1 The Impact of Nutrition on Neurological Wellness Across the Lifespan

Nutrition for Nurses6.1 The Impact of Nutrition on Neurological Wellness Across the Lifespan

Learning Outcomes

By the end of this section, you should be able to:

  • 6.1.1 Describe the impact of nutrition on the neurological system during pregnancy.
  • 6.1.2 Describe the impact of nutrition on the neurological system during infancy.
  • 6.1.3 Describe the impact of nutrition on the neurological system during childhood.
  • 6.1.4 Describe the impact of nutrition on the neurological system during adolescence.
  • 6.1.5 Describe the impact of nutrition on the neurological system during adulthood.
  • 6.1.6 Describe the impact of nutrition on the neurological system during later adulthood.


Diet during pregnancy has been shown to have a significant impact on fetal neurodevelopment in a number of ways. Several nutrients and micronutrients have been shown to impact neural tube formation and other aspects of neurological development (Cortés-Albornoz et al., 2021). The developing brain of the fetus consumes more than half of the available nutrition delivered via the placenta, mainly in the form of glucose. The developing fetal brain is vulnerable to insufficient macronutrients and micronutrients, especially in the first stages of pregnancy. Nutrition during pregnancy is of critical importance to both the developing fetus and the mother. This section will discuss the effect of specific nutrients on healthy brain function for both the mother and the developing fetus. Specific vitamins and minerals, such as vitamins A, B9 (folate), B12 (cobalamin), D, E, and K, as well as certain minerals, such as copper, iron, creatine, choline, zinc, and iodine, are required to prevent a host of neurological conditions in the fetus. They can also impact rates of maternal preeclampsia and postpartum depression.

Table 6.1 outlines the recommended daily allowances for micronutrients for women and men.

Vitamin Recommended Daily Allowance (RDA) Food Sources
Vitamin A 700–900 µg/day Sweet potato, cantaloupe, carrots, liver, eggs, mango, spinach, pumpkin, butternut squash
Vitamin C (ascorbic acid) Adult females:
75 mg/day

Adult males:
90 mg/day
Citrus fruits, kiwi, broccoli, strawberries, Brussels sprouts, cantaloupe, tomatoes, tomato juice
Vitamin D (calciferol) 600 IU/day Fish liver oil, salmon, swordfish, tuna, fortified foods, sardines, beef liver
Vitamin E
15 mg/day Red bell pepper, pumpkin, beets, collard greens, spinach, sunflower seeds and oil, almonds, peanut butter, peanuts
Vitamin K (phylloquinone) 90–120 mg/day Canola and soybean oils, leafy green vegetables
Biotin (vitamin B7) 30 mcg/day Eggs, peanut butter, mushrooms, avocados, almonds
Calcium Adult females:
1000–1200 mg/day

Adult males:
1000–1200 mg/day
Dairy (cheese, yogurt), winter squash, edamame, sardines, salmon, almonds
Chromium 10 µg/day Grape juice, meat, Brazil nuts, whole wheat, mussels, broccoli
Cobalamin (vitamin B12) 2.4 mg/day Dairy products, eggs, poultry, fish, meat, fortified cereals, nutritional yeast
Copper 0.9 mg/day Organ meats, shellfish, fish, nuts, seeds, whole grains, chocolate
(vitamin B9)
400 µg/day Fresh fruits, whole grain, peanuts, beans, dark green leafy vegetables
Fluoride 3 mg/day Brewed tea, coffee, fluoridated water, shellfish, potatoes, oatmeal, raisins
Iodine 220 µg/day Fish, dairy (milk, yogurt, cheese), iodized salt
Iron 18–8 mg/day Nuts, dried fruit, whole grain pasta, bread, legumes, tofu, oats, various meat sources
Magnesium Adult females:
310–320 mg/day

Adult males:
400–420 mg/day
Whole grains, dark green leafy vegetables, dried beans, legumes
Niacin (vitamin B3) 14–16 mg/day Red meat, poultry, bananas, legumes, nuts, seeds, brown rice, fortified cereals, breads
Phosphorus 700 mg/day Dairy (milk, cheese, yogurt), fish, eggs, nuts legumes, vegetables, grains
Pyridoxine (vitamin B6) 1.3 mg/day Salmon, avocado, chickpeas, dairy, milk, sunflower seeds, spinach, beef, bananas
Riboflavin (vitamin B2) 1.1–1.3 mg/day Salmon, chicken breast, organ meats, lean beef, eggs, cheese, yogurt, dairy, milk
Thiamin (vitamin B1) Adult females:
1.1 mg/day

Adult males:
1.2 mg/day
Salmon, eggs, pork, fish, liver, sunflower seeds, beans, nutritional yeast
Selenium 55 mg/day Brazil nuts, bananas, eggs
Zinc 8–11 mg/day Meat, seafood
Table 6.1 Micronutrient Daily Allowances and Sources for Adult Females and Males (sources: CDC 2020, CDC, 2021; CDC, 2022; NIH, 2021; NIH, 2022a; NIH, 2022b; USDA, 2019)

Nutrition and Fetal Neurologic Development

Undernutrition during pregnancy, especially too little protein (46–71 g of protein per day generally recommended during the first and second trimesters of pregnancy), can result in miscarriage, poor fetal neuronal growth (Murphy et al., 2021; Stean et al., 2023), and improper development of the hypothalamus (Sun, et al., 2020). Altered nutritional states such as maternal obesity, high-fat diet, and undernutrition, as well as caffeine intake (less than 200 mg/day recommended) can have a substantial impact on the developing fetal neurological system and can predispose the child to a variety of disorders not only in the early postpartum period, but also in adulthood. A pregnant person's intake of approximately 650 mg of long-chain polyunsaturated fatty acids is essential for the development of the fetal brain and retina, and an absence of these essential nutrients can lead to pregnancy complications and compromised fetal outcomes (Duttaroy & Basak, 2020: Murphy et al., 2021).

Altered nutritional states among pregnant clients in low- and middle-income countries has been shown to increase the risk for preterm and low-birth weight infants, perinatal infant death, and an increase in both mental and physical developmental problems throughout the lifespan (Chea, et al., 2023). Undernutrition may result in impaired brain growth, visual memory problems, and delayed speech, and possibly a lower IQ in the child (Georgieff, et al., 2018). The health of the male parent can also impact fertility and fetal health. The quality and quantity of sperm produced, as well as sperm mobility, can be related to the male parent’s general health, weight, and volume of alcohol consumed.


Several requirements for micronutrients increase during pregnancy, especially iron. The development of gray matter in the brain, as well as the structure of dendrites, motor functioning, language ability, and academic performance, are correlated to adequate iron intake (30–40 mg/day). Iron is available in meats (including organ meats such as heart, liver, kidney, and tongue), poultry, fish, and eggs and generally requires maternal supplementation to reach the recommended daily intake (Georgieff, et al., 2020). Choline, another micronutrient (450 mg/day is recommended), plays an important role in cognitive function, especially neural tube development, intelligence, and sensory gating ability. Choline is available in chicken, beef, eggs, and dairy (Steane, et al., 2023). Zinc (11 mg/day recommended) is associated with appropriate movement, normal heart rate variability, and stability of autonomic nervous system. It is available in red meat, shellfish, poultry, pork, and dairy, as well as in fortified cereal, beans, and nuts. Because zinc is essential to carbohydrate and protein metabolism, a deficiency of zinc can be associated with brain degeneration and a decrease in memory and learning, and can lead to a host of neurological disorders (Choi, et al., 2020).

Vitamin A facilitates the patterning of neurons, the development of axons, and the development of the body’s main organs. The pregnant client requires approximately 600 mg/day of vitamin A. Milk and yogurt are rich in vitamin A (Figure 6.2), which is also found in eggs; oily fish; many orange and yellow fruits and vegetables, such sweet potatoes; and leafy green vegetables, such as spinach (Carazo et al., 2021). Given the abundance of vitamin A in the diet, and storage supply of about 4 months in the tissues, supplementation is generally not recommended, because high doses of vitamin A can cause liver toxicity and increase the risk for birth abnormalities.

A bowl of yogurt topped with blueberries and granola.
Figure 6.2 Yogurt is not only rich in vitamin A, but also is a source of calcium, iodine, phosphorus, and riboflavin. (credit: “Yogurt with Blueberries and Granola” by Alabama Extension; ACES | Margaret Barse & Aimee Lewis/Flickr, Public Domain)

Several B vitamins are critical to the normal development of the fetal neural tube. For example, vitamin B12 (cobalamin) and vitamin B9 (folate) support the development of neurons and myelination of the axons, which carry neurologic messages throughout the body. Folate is integral in fetal brain development, especially during periods of rapid growth and development (Li et al., 2019). Requirements for the B vitamins increase by 50% during pregnancy. For pregnant clients, the requirement is approximately 400 mcg/day of B vitamins.

Vitamin D has a role in regulating gene expression and brain development as well as several other functions, such as the regulation of calcium, the development of dopamine, skeletal regulation, and language development (Larqué, 2018). The maternal requirement of vitamin D during pregnancy is approximately 1500–2000 UL and may be consumed in the diet by eating fatty fish, eggs, beef, and fish liver oil (Chauhan et al., 2023). A deficiency of vitamin D may result in attention deficit hyperactivity disorder and poor language development (Tous, et al., 2020).

Iodine plays an important role in thyroid hormone synthesis and is therefore essential for neurologic development of the fetus. During the first half of pregnancy, a deficiency of thyroid hormone (specifically T4) can disrupt the development of neurons, synapses, and myelin formation. A client with severe iodine deficiency is more likely give birth to a baby with decreased IQ scores or possibly cretinism (altered intellectual disability, small stature, and thickening of the facial features). Supplementing a normal diet with 250 mg/day of iodine is recommended for pregnant clients. Clients contemplating pregnancy may be encouraged to begin iodine supplementation prior to conception. Iodine is available in the diet in most sea fish, especially shellfish, and is fortified in many cereals and grains, in addition to iodized salt. Prenatal supplementation with each of these micronutrients (except vitamin A) is generally recommended. The requirements for each of these are met in daily intake of a prenatal vitamin, so additional supplementation is not recommended.

The phospholipids (fats that contain phosphorus) in the plasma membrane, called gangliosides (lipids that carry sialic acid residues), are essential for fetal brain maturation and can determine normal neural repair and apoptosis, neurotransmitter release, and transmission of signals across cells (Sipione et al., 2023). Severe neurodevelopmental and neurodegenerative problems can result from decreased levels of gangliosides. Clients who carry a rare autosomal recessive gene mutation, such as Tay-Sachs disease (a rare disease that destroys nerve cells in the brain and spinal cord), cannot synthesize gangliosides due to the deficiency of an enzyme (hexosaminidase A). These clients will develop an accumulation of these fatty substances, primarily in the brain and spinal cord. Symptoms include slowed development in the infant, and stiff muscles and seizures may manifest. A similar gene mutation affecting gangliosides can result in spastic paraplegia and intellectual disabilities, due to a deficit of gangliosides in the hippocampus (Okuda, 2019). Egg yolks, meat, and milk are the dietary sources of gangliosides (Okuda, 2019).

While a deficiency of nutrients has been shown to have a negative impact on fetal brain development, a high-fat maternal diet and obesity during pregnancy have been correlated to autism and attention deficit disorder among newborns, behavioral disorders in children, and a propensity for obesity in adulthood (Cortés-Albornoz, et al., 2021). Also, high consumption of sugar during pregnancy, especially fructose, has been associated with altered development of the prefrontal cortex and subsequent autism spectrum disorder (Rivell, et al., 2019). Obesity among pregnant clients has been associated with infants exhibiting altered immunity, higher rates of attention deficit hyperactivity disorder, and autism or intellectual developmental delays than children born to mothers with a normal weight (Sanchez et al., 2018). The nature of the maternal diet has been shown to impact the bacterial colonization in the infant’s gut in the early postpartum period, which can impact subsequent neurodevelopment across the lifespan (Al Rubaye, et al., 2020).

As shown in Applying Clinical Judgment to Promote Nutrition for Neurological Wellness, omega-3 fatty acids are required for healthy brain function. A deficiency of these essential brain-building blocks results in brain inflammation and possibly brain injury and stroke. Approximately 1 in every 3,500 full-term infants in the United States will develop an ischemic stroke when expecting mothers do not consume adequate amounts, especially in the first trimester of pregnancy (Dunbar & Kirton, 2018).

Prenatal alcohol intake in any amount has been shown to have a detrimental effect on congenital cognitive impairment, including fetal alcohol spectrum disorder and, if severe, fetal alcohol syndrome (Oei, 2020). Maternal caffeine intake crosses over to the placenta and is associated with altered sleep and movement as well as the ability to learn, because the developing fetus does not possess the enzymes to metabolize caffeine. Maternal caffeine intake of more than 200 mg/day has been associated with shorter stature in early childhood (Gleason et al., 2022).

Impact on the Client’s Health During Pregnancy

The impact of pregnancy on the neurological health of the client is of great concern. Pregnant people’s rates of morbidity and mortality have risen dramatically in recent years, especially in non-Hispanic Black and Hispanic individuals (Hoyert, 2023). Hormones change during pregnancy, and particularly the rise in progesterone can affect maternal health. Current nutritional recommendations for neurologic health during pregnancy include a diet rich in fresh fruits and vegetables, whole-grain cereals, milk, and dairy products, as well as meat, fish, and eggs as they are rich in vitamins A, C, and D as well as calcium and phosphorus.

During the antepartum period, many people have an increased interest in eating carbohydrates, and if toothbrushing does not occur as often, dental caries and plaque are more likely. Dental infections and caries have long been associated with the development of a stroke, but dental inflammation has also been associated with premature contractions, placing the fetus at risk for premature birth, low birth weight babies (Alrumayh et al., 2021). While regular oral care during pregnancy (toothbrushing and flossing at least twice a day) require diligence during pregnancy, dental procedures such as extractions and root canals, if required, are performed with caution during pregnancy, and may be delayed until after the first trimester.

Sugars, dried fruits, and chewy candy should be avoided to promote optimal dental health, as this can also impact the neurologic health of the pregnant client. Gingivitis and tooth decay are more likely during pregnancy, and this is thought to be associated with hormonal changes, especially estrogen and progesterone. Those who develop morning sickness with vomiting during pregnancy are more likely to have gingivitis, which can lead to an acidic environment in the mouth and, consequently, tenderness and minor bleeding can occur, making toothbrushing uncomfortable.

High levels of fat in the maternal diet and an inactive lifestyle are associated with high cholesterol and high blood pressure. A significant portion of people who consume a high-fat diet and are inactive during pregnancy develop preeclampsia, placing them at a five-times higher-than-average risk for stroke, not only in the peripartum period, but also in later life (de Havenon et al., 2021). Pregnant clients who develop frequent migraine headaches are more likely to develop preeclampsia during pregnancy (Zambrano & Miller, 2019). Clients who develop an infection such as a urinary tract infection or sepsis during their pregnancy are more likely to be readmitted to the hospital for a stroke after the delivery (Zambrano & Miller, 2019). Approximately 7.4% of maternal deaths are a result of stroke. Stroke is now the second-leading cause of maternal death in Japan among women older than 40 years, and many of these are considered preventable (Zambrano & Miller, 2019). A large percentage of maternal deaths in the United States are associated with inadequate prenatal care and preeclampsia (Elgendy et al., 2021). In addition to preeclampsia and stroke during pregnancy, Bell’s palsy can develop during delivery, and a temporary paralysis of one side of the face can last up to 6 months postpartum.

Special Considerations

Risk for Stroke During Pregnancy or Delivery

Black clients with a history of hypertensive disorders of pregnancy (HDOP) are at a 66% higher risk for experiencing a stroke (Sheehy et al., 2023). Their risk for stroke during pregnancy or delivery is doubled due to the possibility of a hypercoagulable state, eclampsia, or preeclampsia (Richardt et al., 2023), and this may be in part related to poor prenatal nutrition.

The Client Without Neurological Illness

The consequences of chronic conditions may undermine pregnancy or aggravate the maternal condition, and nutritional requirements may exceed the recommendations of a normal pregnancy. Demyelinating polyneuropathies, inflammatory muscle disease, and myasthenia gravis may become more extreme during pregnancy. Although there are no specific nutritional recommendations for these conditions during pregnancy, an interprofessional approach of physicians, scientists, nurses, dieticians, and other specialists are often required to best manage symptoms and to optimize nutritional support.

Although a variety of chronic conditions can impact maternal nutrition in pregnancy and lactation, type 1 diabetes, type 2 diabetes, gestational diabetes, and systemic lupus erythematosus (SLE) can have a profound effect on maternal and fetal health. These conditions are discussed next.

Type 1 Diabetes, Type 2 Diabetes, and Gestational Diabetes

Recent improvements in the monitoring of blood glucose have dramatically increased a pregnant client’s ability to maintain normal blood glucose levels. Glucose is an osmotic diuretic and because of this effect,clients with diabetes may be subject to dehydration. Diabetic ketoacidosis is more common in type 1 diabetes than in other types of diabetes. The dietary requirements for a pregnant or lactating client with type 1 diabetes are essentially the same as those for a client without a chronic disease or condition, with a few recommendations. Normal blood sugar should always be maintained. This can be managed using continuous blood glucose monitoring, and an insulin pump for type 1 diabetes may be recommended for type 2 diabetes and gestational diabetes as well. In some cases, metformin may be used for gestational diabetes and type 2 diabetes. The effect of insulin type 1 diabetes and metformin type 2 diabetes are similar in that they both produce normoglycemia and optimize fetal neurologic outcomes. Although metformin crosses the placental barrier, it was shown to be slightly superior in preventing maternal weight gain and hypertension (Newman et al., 2023). Maternal weight gains of 11–18 kg (24.25–39.68 lb) are generally recommended. Diet should consist of 50% unprocessed carbohydrates (no concentrated sweets), 20% protein, and 30% polyunsaturated fats (Newman et al., 2023). Although a short-term drop in blood glucose is generally well tolerated by a developing fetus, long-term hypoglycemia can have devastating effects on fetal brain development.

Systemic Lupus Erythematosus (SLE)

Systemic lupus erythematosus (SLE) is associated with several pregnancy-related complications, especially during delivery. Although diet alone is insufficient to manage SLE, the gut is affected by SLE. A diet that maintains a healthy gut microbiome should include each of the food groups and food from all the colors of the rainbow, such as blueberries, strawberries, corn, oranges, eggplant, broccoli, and tomatoes, to increase phytonutrients. The presence of any allergies must be carefully considered when selecting foods. Antepartum clients are often advised to avoid fatty red meats, refined sugar and flour, fried foods, alcohol, gluten, and processed foods. Bananas are recommended because they are high in magnesium, which helps to protect the fetal brain, promotes normal fetal growth, and helps prevent preeclampsia. Dark green vegetables, such as kale and spinach, are rich in iron and can mitigate the side effect of anemia resulting from some anti-inflammatory medications that may be used for maternal treatment of SLE.

Clients with Chronic Neurological Illness

Clients with neurologic conditions can generally experience a healthy pregnancy. However, research is ongoing to study the impact of multiple sclerosis, migraines, aneurysms, myasthenia gravis, and epilepsy during pregnancy (Xu, 2019). Some medications to treat seizures can be successfully administered during pregnancy. Caution should be employed when considering the effect of medications to treat the neurologic condition of the mother. Headaches can be sign of preeclampsia, so the pregnant client with a history of migraines should be closely monitored. Medications to treat headaches or other neurologic conditions must be carefully planned to avoid those that cross the placental barrier. The risk for stroke is highest in clients with preeclampsia, so blood pressure must be carefully monitored and treated.

Conditions such as Guillain-Barré syndrome can be potentially lethal. This nervous system condition presents with acute ascending weakness and may progress to acute respiratory failure if left untreated with respiratory support. Treatment of Guillain Barré syndrome is the same for pregnant and nonpregnant clients (Leonhard et al., 2019).

In terms of nutritional support, diets that are rich in macronutrients and micronutrients for a client without a neurologic condition are considered safe for the pregnant client with a chronic neurologic condition.


The development of the brain and nervous system is the most rapid in the first two years of life. Given the known benefits of breastfeeding over infant formula, nutritional support with human breast milk is critical to neurological development during infancy. Specifically, the development of visual function and other cognitive domains are improved when babies are breastfed throughout infancy (Nieto-Ruiz, 2019). A deficiency of a host of macronutrients and micronutrients, such as protein, carbohydrates, certain fats, iron, zinc, copper, iodine, selenium, vitamin A, choline, folate, and vitamin B12 (cobalamin), have been shown to be essential in preventing certain neurologic disorders, such as anorexia, irritability, growth retardation, and developmental regression (Nawaz, et al., 2020). Iron deficiency alters myelin formation in infancy as well as the development of the hippocampus (brain structure responsible for emotion, memory, and autonomic nervous system) and neurotransmitters. The impact of maternal iron deficiency includes a reduction in memory, motor, and behavioral affect in the infant. A zinc deficiency interferes with both hippocampal and cerebellar development. Polyunsaturated fatty acids also affect membrane function and the development of appropriate synapses.

Lactating Clients

To ensure the adequacy of breast milk for infant nutrition, lactating clients should include protein-rich foods, such as meat, poultry, fish, eggs, dairy, beans, nuts, and seeds, 2–3 times a day (CDC, 2023a). Three servings of vegetables that include dark greens should also be consumed, as well as 2 servings of fruit. Whole-grain foods such as cereals, breads, pastas, and oatmeal are also recommended. Seafood is recommended if it is low in mercury. A healthy diet should include most of the macronutrients and micronutrients that are required for lactating clients, but a multivitamin and mineral supplement may also be recommended to ensure adequate nutrition for both the mother and infant. Caloric intake should increase by approximately 330–400 calories per day to produce high-quality breast milk (CDC, 2023).


The brain reaches 80% of its adult weight by age 3 (Bethlehem et al., 2022) and is exceptionally sensitive to any nutritional deficiencies. Glucose metabolism in the brain continues to accelerate from birth to 4 years. At age 4 years, glucose metabolism occurs at approximately twice the rate as that of an adult. This accelerated metabolic rate continues until age 9 or 10 years and then begins to slow to the adult level during late adolescence. Because the brain cannot store glucose, a continuous supply of glucose by eating frequent meals is paramount. The effect of overnight fasting can have an adverse effect on children; therefore, breakfast is an extremely important meal to nourish the brain and improve cognitive function.

A breakfast that is rich in low glycemic carbohydrates is known to result in optimal cognitive performance. Different types of breakfast may impact the development and performance of various gray and white matter in the brain (Arora, 2022). The effect of long-chain polyunsaturated fatty acids (LCPUFA) is essential for brain function, especially in the brain’s gray matter. Given the rapid brain development, especially in early childhood, it is critical to ensure adequate micronutrients intake, which can be challenging. Deficiencies of micronutrients such as iron, folate, and vitamin B12 may become evident around age 5–6 years, as deficiencies are associated with poor cognitive performance, especially in the school setting (Arora, 2022).

Micronutrient deficiency may be more apparent among children whose mothers had experienced inflammatory bowel diseases, celiac disease, or ulcerative colitis, as these vitamins are poorly absorbed in the intestines in these conditions. For children who are deficient, dietary supplementation with micronutrients can improve cognitive performance, especially if the breakfast is low in sugar (Arora, 2022).

The prevalence of pediatric obesity climbed to 19.7% between 2017 and 2020 in the U.S. (CDC, 2023b). Some studies suggest that there is a biological link between childhood obesity and lower cognitive function and that this effect is related to insulin resistance. However, these studies are inconclusive, especially when sociodemographic factors are considered. For healthy children, the Mediterranean diet is an example of a diet that can provide the essential nutrients required for the development of a healthy neurologic system.


Multiple studies of the diets of adolescents have shown that there is a direct relationship between diet and brain development (Arora, 2022). Diet is associated with various aspects of mood, anxiety, depression, and other mental health disorders. A disproportionate percentage of teens are known to have an eating disorder (i.e., anorexia nervosa or bulimia), and this has a direct result on neurotransmission within the brain (Aurora, 2022). A poor diet during adolescence can result in structural changes in the brain, causing poor cognitive function, mood changes, and emotional imbalances. These structural changes may become permanent, as the brain is still developing in adolescence, and the processes of neurotransmission in the brain is still evolving during this period. For example, dopamine is a neurotransmitter in the brain that is responsible for pleasure and reward responses, and if the brain interprets a message that a cheeseburger or ice cream is a reward, dopamine is released. This dopamine effect is much more pronounced in an adolescent brain than in an adult, because adolescents have more dopamine receptors than adults. When the adolescent brain is rewarded with poor diet choices, this impact carries over into adulthood.

Healthy food choices, including a moderate intake of low-fat dairy and meats with low levels of refined sugars, promote the development of healthy bacteria, acting as natural probiotics. Bacteria in the stomach influence the production of serotonin and create a lining of the stomach that protects against harmful bacteria, limiting inflammation and improving the absorption of nutrients. Serotonin is produced in the intestine and regulates sleep, appetite, mood, and pain inhibition. The creation of healthy bacteria in the gut is critical, because bacteria activate the pathway between the brain and GI tract.

A poor diet during adolescence creates a disruption in healthy gut bacteria, resulting in an inability to absorb nutrients or produce serotonin. The neurologic impact of a poor diet during adolescence is a reduced attention span, an inability to learn or remember new information, and an inability to regulate one’s mood. The typical teenage diet in the U.S. often includes sugary drinks, processed sugars, fried foods, and an imbalance in healthy nutrients. A poor diet in adolescence also contributes to the development of depression, sleep disturbances and mood disorders. It can also contribute to an early development of heart disease, type 2 diabetes, memory disturbances, and brain inflammation (Griebsch et al., 2023; Moscatelli et al., 2023). Some teens have tried to reduce processed sugar intake by switching to sports drinks containing aspartame. However, aspartame contains phenylalanine, which increases brain inflammation and can worsen brain function, increasing the risk for developing Alzheimer’s disease and other forms of neurodegeneration (Czarnecka et al., 2021). Conversely, many children and adolescents have moved toward a health-conscious lifestyle that includes vegetarian or vegan diets (Figure 6.3). Although nutritional needs can generally be met with a plant-based diet, the nutrient requirements of adolescents are higher per kilogram of body weight than adults, and this consideration is important in diet planning. Nutritional deficiencies, especially of omega-3 fatty acids, iron, zinc, and B12, are more common among vegetarians and vegans, requiring close monitoring by health care professionals (Rudloff et al., 2019).

Pizza with tomato sauce, red bell peppers, mushrooms, black olives, salami, and cheese, and spiced with red chili pepper, chives, oregano, thyme, rosemary, and basil, being cooked on a grill.
Figure 6.3 Poor diet choices can be improved by replacing unhealthy ingredients, such as those found in all-meat pizzas, with healthier plant-based options such as bell peppers or mushrooms. (credit: “Tonight’s Pizza” by Alan Levine/Flickr, Public Domain)


The needs of adults change as aging occurs. While adulthood begins at 18 years, the needs of adults change as a person enters their 30s, 40s, 50s and 60s due to changes in metabolic rate, activity levels, the physical demands by occupation, hormonal changes, and a wide range of other factors. Moreover, nutritional needs may vary based on a person's sex. For example, health and nutrition for females must consider important factors across the lifespan, such as pregnancy, breastfeeding, and menopause. As females age, they are at a higher risk than males of cardiac disease, breast cancer, and osteoporosis.

Specific recommendations for macronutrients to maintain neurologic health can also vary depending on a range of factors, including a person's sex, environment, and other characteristics or circumstances. The degree of physical activity alters protein requirements. Physical body size and weight alter caloric needs. Carbohydrates provide the main source of energy. In general, 130 g/day of carbohydrates are recommended, and these should be consumed from high-fiber whole grains, fruits, vegetables, and legumes, as well as low-fat yogurt and other dairy products. A dietary intake of polyunsaturated fats, which can be found in vegetable oils, nuts, seeds, and fish oil, should comprise around 15% of the adult diet.

While caloric needs are higher in early adulthood, this need often declines as a person ages. Because many adults do not adjust their diet as they age, overconsumption of calories coupled with a decline in physical activity often results in adult-onset obesity, which can be associated with poor cognitive status. Some estimates report that 42.5% of adults in the U.S. are overweight or obese, and it varies by race and ethnicity (Fryar, et al. 2021). Due to the inadequacies of the traditional Western diet, many adults are also nutrient deficient, especially in micronutrients, even if their caloric intake exceeds the body’s needs.

Older Adults

The changing nutritional requirements in older adults are more relevant than ever before. In 2019, estimates show that there were more than 703 million people globally over age 65, and more than 50 million were diagnosed with dementia. By the year 2050, it is projected that 1.5 billion people will be over age 60, and 153 million will be living with dementia (Alzheimer’s Disease International, 2023). Nutritional strategies, including the intake of specific macronutrients and micronutrients, such as those rich in B vitamins, long-chain polyunsaturated fatty acids, and flavonoids (foods that have antioxidant properties due to their variable phenolic composition, like fruits and vegetables, tea, wine, and whole grains), have been shown to delay or slow the onset of age-related conditions. Supplementing the diet with micronutrients has been shown to improve cognition in some studies of clients with Alzheimer’s disease, but the best health benefits have been verified with a varied multinutrient-rich diet rather than supplements alone (Fei et al., 2022).

The process of aging is associated with a loss of muscle mass. While a variety of food sources are recommended to support brain health, those containing foods rich in iron, folate, calcium, and vitamins A, C, and D, are particularly important for supporting muscle mass as well. Adequate intake of vitamin B12 among older adults is recommended to maintain the integrity of nerve cells. Foods high in vitamin B12 include eggs, fortified breakfast cereal, and certain fish, such as tuna. However, the absorption of some vitamins may be reduced due to both age-related and other changes in the gut, as well as the effect of medications like metformin, proton pump inhibitors, vitamin C supplements, colchicine, and medications that are used to treat peptic ulcers and other gastrointestinal problems. The tendency of older adults to become dehydrated can also affect the ability to absorb nutrients, and an increase in water intake as well as fresh fruits and vegetables can help to overcome dehydration. Special nutritional considerations for older adults should include an understanding of maintaining adequate nutrient and fluid intake, the client’s sensitivities to certain foods, and any challenges with chewing or swallowing.

Unfolding Case Study

Part A

Read the following clinical scenario and then answer the questions that follow. This case study will evolve throughout the chapter.

A nurse working in an internal medicine clinic is assessing John Everett, a 77-year-old Black male. His daughter accompanies him for this routine exam. The nurse asks about John’s appetite and recent food intake. He reports that he eats “ok,” but his daughter says that he is not eating very well. The nurse reviews John’s record and notes that he has lost 10 lbs since his last visit. John lives alone, and his daughter is concerned he is not eating enough nutritious food.

Which of the following age-related findings is associated with older adults?
  1. Increased appetite
  2. Decreased muscle mass
  3. Increased caloric intake
  4. Decreased hydration requirements
Which of the following statements by the client indicates that he is at risk for impaired nutrient absorption?
  1. “I don’t drink much water.”
  2. “I eat canned vegetables.”
  3. “I take my blood pressure medicine with food.”
  4. “I eat a lot of snacks and small meals.”

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