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Clinical Nursing Skills

17.2 Factors Affecting Nutrition

Clinical Nursing Skills17.2 Factors Affecting Nutrition

Learning Objectives

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

  • Analyze the physiological factors affecting nutrition
  • Understand the sociocultural, behavioral, and lifestyle factors affecting nutrition
  • Examine the psychological factors affecting nutrition

Good nutrition is associated with a high quality of life. This is true for all people, whether young or old, wealthy or poor, athletic or sedentary. Nutrient-rich foods and fluids must be available in adequate amounts to meet the specific metabolic needs of each individual. Meeting these needs is a dynamic process involving the ingestion, digestion, absorption, and metabolism of each nutrient according to its biochemical makeup. There are many factors that influence these biological processes. Some factors have direct, physiological effects on these processes, such as the stage of growth and development or the presence of underlying medical conditions. Some factors have subtler effects, such as cultural or religious influences. The meaning of food and its association with self-image can have psychological effects that influence a person’s relationship to nutrition. This module explores some of the physiological and psychological factors that positively or negatively impact nutritional health.

Physiological Factors

Nutrition impacts many physiological processes. The physiology of digestion involves the breakdown of foodstuffs into absorbable nutrients. Digestive processes include mechanical digestion, propulsion, chemical digestion, and absorption (Figure 17.4). The process of breaking down, or metabolizing, nutrients is influenced by many factors, including the following:

  • digestive organ function responsible for the breakdown, absorption, and metabolism of nutrients
  • kidney function responsible for fluid balance
  • cardiovascular function responsible for transportation of nutrients
  • endocrine function responsible for the production of hormones that control metabolic processes
  • neurocognitive function responsible for perceptions of hunger, satiety, and thirst

Bones, muscles, and sensory organs are all involved in nutrient pathways. In fact, every cell in the body utilizes nutrients. Any process that disrupts the metabolic pathways in the body has the potential to negatively impact nutritional health.

Diagram showing four phases of digestion: Propulsion: Swallowing (oropharynx), Peristalsis (esophagus, stomach, small intestine, large intestine); Chemical digestion; Mechanical digestion: Chewing (mouth), Churning (stomach), Segmentation (small intestine); Absorption: Nutrients and water to blood vessels and lymph vessels (small intestine), Water to blood vessels (large intestine); labels show ingestion of food, pharynx, esophagus, stomach, small intestine, large intestine, feces, anus, defecation
Figure 17.4 There are four phases of digestion, beginning with the ingestion of food and ending with the elimination of waste. (credit: modification of work from Anatomy and Physiology 2e. attribution: Copyright Rice University, OpenStax, under CC BY 4.0 license)

Some physiological factors have a profound effect on metabolic pathways. A person’s genetic makeup, stage of growth and development, medications, and underlying medical conditions all directly impact how their body processes nutrients. Other factors, such as environment, socioeconomic conditions, and personal preferences, can directly influence food choice and nutrient availability. Consequently, it is important for the nurse to consider the holistic needs of every patient, including the many factors that influence the nutritional demands on the human body.

Developmental Level

The human body is engineered to grow and develop through structured, organized, time-sensitive processes. These processes occur naturally within the body and follow predictable patterns for physiological and cognitive maturity. Across a person’s life span, nutritional requirements differ based on the unique developmental needs at each stage of development. For example, caloric needs are based on body weight, activity level, and metabolic demands. As growth and development occur, these factors change. For example, in utero body weight is low, but metabolic demands are high. At birth, growth measures, such as head circumference, length, and weight, help identify individual risk for malnutrition. As the child grows, body weight increases, activity levels vary, and metabolic demands continue.

Growth charts are tools for measuring healthy growth trends based on established height and weight norms. At each life stage, developmental markers can be tracked to help with early identification of developmental delays and abnormalities. Timely nursing intervention along the growth and development path can dramatically improve health outcomes and prevent long-term negative health effects associated with early nutritional deficits.

Real RN Stories

Encouraging Diet Modifications in a Family
Nurse: Julie, RN
Clinical setting: Community clinic
Years in practice: 10
Facility location: Texas

I remember when I was a student nurse, and we were assigned clinical rotations in the local community clinic. One day a mom came into the clinic to seek care for her 10-year-old. She reported her daughter had been having increased fatigue and was steadily gaining weight over the last year. The mom said, “Last year she was in volleyball and soccer and was so active; now all she wants to do is lay around watching TV and eating junk food. I am concerned she is developing unhealthy habits at an early age.”

Upon further assessment, I noticed the girl’s diet consisted of excessive amounts of salt, sugar, and fat. I was able to educate the mom how at this age, almost one-fourth of all American children have elevated cholesterol. We also discussed the need for increased vitamin D and calcium. I explained how these are vital requirements as her bones enlarge to prevent osteoporosis later in life. The physician ordered lab work and provided the family a referral to a nutritionist. The family and I discussed activities that sparked their interest in trying them out together, and they verbalized different diet modifications they planned to incorporate immediately. That day I left clinical feeling like I truly made a difference in this young child’s life.


If typical growth and development patterns occur, chronological age can predict generalized nutritional needs. Recommended DRIs provide guidelines for nutrient needs across an individual’s life span. Table 17.5 provides an example. Note that the recommendations are based on weight (kilograms) and age. Consider the needs of a child versus the needs of an adult. Protein, calories, and calcium are needed in greater amounts as children grow, then level off in adulthood. There are also unique recommendations for older adults, who experience loss of muscle and bone mass and lower activity levels due to declining mobility and thus require fewer calories than their younger counterparts. Older adults also have unique dietary needs due to their higher risk of chronic disease, development of poor dentition, and socioeconomic changes that affect the type and amount of nutrients consumed.

Age (years)
Macronutrient 2–3 4–8 9–13 14–18 19–30 31–50 50+
Protein (g) 13 19 34 52 56 56 56
Protein (% kcal) 5–20 10–30 10–30 10–30 10–35 10–35 10–35
Carbohydrate (g) 130 130 130 130 130 130 130
Carbohydrate (%) 45–65 45–65 45–65 45–65 45–65 45–65 45–65
Fat (% kcal) 30–40 25–35 25–35 25–35 20–35 20–35 20–35
Fiber (g) 14 20 25 31 34 31 28
Table 17.5 Comparison of Male Macronutrient Needs: Toddler to Adult (Source: U.S. Department of Agriculture & U.S. Department of Health and Human Services, 2020.)


Nutritional needs differ between sexes largely due to hormone differences. A chemical mediator that circulates in the body and has a specific stimulating or inhibiting action on the target organs is called a hormone. Table 17.6 lists some of the hormones that control growth and development, metabolism, adrenal function, and stress. Sex hormones are responsible for the majority of differences between the biological sexes. These differences can result in distinctive caloric and other nutritional needs, particularly beginning in adolescence. For example, females require higher levels of iron during childbearing years due to the hormonal influences of menstruation and pregnancy. Pregnancy also changes caloric needs. More information regarding specific pregnancy-related nutritional needs is provided later in this chapter.

Endocrine Gland Associated Hormones Chemical Class Effect
Pituitary (anterior) Growth hormone (GH) Protein Promotes growth of body tissues
Pituitary (anterior) Prolactin (PRL) Peptide Promotes milk production
Pituitary (anterior) Thyroid-stimulating hormone (TSH) Glycoprotein Stimulates thyroid hormone release
Pituitary (anterior) Adrenocorticotropic hormone (ACTH) Peptide Stimulates hormone release by adrenal cortex
Pituitary (anterior) Follicle-stimulating hormone (FSH) Glycoprotein Stimulates gamete production
Pituitary (anterior) Luteinizing hormone (LH) Glycoprotein Stimulates androgen production by gonads
Pituitary (posterior) Antidiuretic hormone (ADH) Peptide Stimulates water reabsorption by kidneys
Pituitary (posterior) Oxytocin Peptide Stimulates uterine contractions during childbirth
Thyroid Thyroxine (T4), triiodothyronine (T3) Amine Stimulates basal metabolic rate
Thyroid Calcitonin Peptide Reduces blood Ca2+ levels
Parathyroid Parathyroid hormone (PTH) Peptide Increases blood Ca2+ levels
Adrenal (cortex) Aldosterone Steroid Increases blood Na+ levels
Adrenal (cortex) Cortisol, corticosterone, cortisone Steroid Increases blood glucose levels
Adrenal (medulla) Epinephrine, norepinephrine Amine Stimulates fight-or-flight response
Pineal Melatonin Amine Regulates sleep cycles
Pancreas Insulin Protein Reduces blood glucose levels
Pancreas Glucagon Protein Increases blood glucose levels
Testes Testosterone Steroid Stimulates development of sex characteristics including a deeper voice, increased muscle mass, development of body hair, and sperm production
Ovaries Estrogens and progesterone Steroid Stimulates development of sex characteristics including the development of adipose and breast tissue, and prepares the body for childbirth
Table 17.6 Endocrine Glands and Their Major Hormones


Nutritional requirements increase during pregnancy and lactation. The growing fetus puts increased nutritional demands on the body. Increased caloric needs require a nutrient-dense diet to maximize nutrition. Prenatal vitamins are advised to meet increased requirements for micronutrients such as iron, folic acid, iodine, choline, and vitamin D. Optimal nutritional requirements continue during lactation, when the mammary glands produce and release milk for breastfeeding. Increasing intake of pasteurized dairy, eggs, and lean proteins is a healthy way of increasing these nutrients.

Health Status

An individual’s health status is greatly influenced by their overall nutritional status, and vice versa. Individuals in good health experience high levels of well-being and life satisfaction. Healthy people are physically active within their environment and engage in rewarding relationships. Physiologically, good nutrition and hydration balance lead to healthy growth and development patterns. The maintenance of a healthy body weight protects individuals by reducing the risk of chronic disease. Conversely, chronic disease states often present with significant nutritional demands that increase the risk of compromised nutritional health and negative outcomes.

Chronic illness and declining health impact nutritional status in various ways. Some chronic illnesses interfere with an individual’s ability to ingest food properly. For example, a child with a cleft palate may have trouble eating enough calories, or an older adult who suffers a stroke may develop dysphagia (difficulty swallowing) and be unable to swallow food. Some chronic illnesses affect absorption of nutrients within the body. A child with cystic fibrosis may develop pancreatic insufficiency and be unable to absorb fats and proteins. Inflammatory bowel disease can result in poor vitamin B12 absorption. Many chronic diseases cause metabolic dysfunction leading to poor utilization of nutrients. Diabetes, Addison disease, and chronic kidney disease are examples of chronic diseases with significant impact on nutrient metabolism and utilization.

Every chronic disease provides a nutritional challenge. Treatment for heart disease includes restrictions on sodium and fat. Increased calcium and vitamin D are needed to treat bone disorders such as osteoporosis. Treatment for gastroesophageal reflux disease includes limiting acidic foods, spicy foods, and alcohol. There is a nutritional aspect associated with the prevention or treatment of nearly every chronic disease. Avoiding excess calories is important to both the prevention and treatment of obesity and heart disease. Controlling fat consumption reduces the risk of obesity, stroke, and heart disease. Adequate fiber in the diet reduces the risk of colon cancer. Good nutrition, as prevention or treatment, leads to better health outcomes.

Sociocultural, Behavioral, and Lifestyle Factors

Healthy lifestyles are key to wellness and reduction of chronic disease. However, lifestyles are strongly influenced by sociocultural factors that differ for different people. Culture, religion, and economic status play a significant role in food preferences and often give food and mealtimes meaning beyond the ingestion of nutrients. Environmental factors influence availability and quality of food and water. Unhealthy behaviors, such as alcohol and substance abuse, directly influence nutritional status. Many people rely on supplements to counteract the ill effects of unhealthy lifestyles and perceived nutritional deficits. In this section, we briefly explore how these sociocultural factors can influence overall nutritional health.


Cultural competence is a hallmark of patient-centered care. Culture describes the unique patterns of behavior and thought belonging to an identified group or organization. Nutrition and dietary patterns are often an integral part of cultural identity. The United States is home to a vast number of cultures. Cultural beliefs affect types of food eaten and when they are eaten. Some foods may be restricted due to beliefs or religious rituals, whereas other foods may be viewed as part of the healing process or have significant meaning to the celebrations of life. It is essential to consider cultural food preferences when planning nursing care and encourage healthy habits within the context of these foods.

Cultural Context

Cultural Variations

Cultural and religious beliefs often influence food selection and food intake. It is important for nurses to conduct a thorough patient assessment, including food preferences, to ensure adequate nutritional intake during hospitalization. Every culture has variations that make them unique, yet there are also similarities among many. Although a certain dish or ingredient might have originated in one country or culture, global trade has transported fruits, vegetables, and culinary practices to the entire world. For this reason, nurses must never make assumptions about their patients’ diet based on culture or ethnicity. Instead, ask every patient about their food preferences and offer as many healthy choices as possible.


Religious practices can influence nutritional intake, often due to restrictions in specific foods or meal preparation. Both Jewish and Muslim laws prohibit the consumption of pork products, and Hindu scriptures promote a vegetarian diet. Restrictions may vary even within a given religion as people practice varying degrees of strictness to dietary doctrines. Some individuals may observe food restrictions in association with specific religious celebrations. For example, Catholics may observe dietary restrictions during Lent, while practicing Muslims may fast during Ramadan. Food preparation can also be influenced by religious beliefs. Some Jewish people observe Kosher laws which govern the preparation of certain foods (e.g., beef), the prohibition of certain foods (e.g., pork and gelatin), or the combination of some food (e.g., beef served with dairy products), while some Muslim people observe Halal (the Arabic word meaning "permissible" or "lawful") which restricts the consumption of pork, alcohol, and blood products, and and calls for minimal suffering when preparing animal products. Religious practices and beliefs can be complex. It is important to support the nutritional goals of the individual patient by understanding and respecting the religious dietary practices of every patient.

Economic Status

Economic status refers to a combination of economic and social indicators that describe an individual’s overall scale of wealth and status. Factors that contribute to economic status include income, educational level, occupation, and place of residence. Economic status predicts a person’s ability to obtain nutritious food on a routine basis. Individuals with lower incomes have less means to obtain and prepare nutritious foods. Some individuals may live in a food desert: a geographical area where fresh produce and foodstuffs are either too expensive or unavailable. Federal supplemental assistance programs are available to help meet the nutritional needs of underserved and marginalized low-income populations. These include the Supplemental Nutrition Assistance Program (SNAP) and the Special Supplemental Nutrition Program for Women, Infants, and Children (WIC). There are also private organizations such as Meals on Wheels America. Individuals with higher incomes are not immune from nutrition concerns. Excess calories and intake of nutrient-poor foods can lead to obesity and other metabolic disorders due to easy access to food, especially fast food.


Community environments have a large impact on nutritional health. As stated earlier, food deserts can create areas of food insecurity among at-risk populations. This has its greatest impact on infants, children, and older adults, who are often dependent on others for meal preparation and shopping. Urbanization and industrial effects can have detrimental consequences on clean water supplies and spaces for meal preparation. War zones and refugee camps often deal with undernutrition and lack of access to safe, quality food and water.

Along with geographical environments, family structures within communities have a profound effect on nutritional status. People in a state of food insecurity have limited access to adequate food, typically due to economic or social factors. People experiencing the uncertainty of food insecurity or family discord find it difficult to maintain healthy eating routines. School lunch programs are a helpful resource to families in low-income neighborhoods. Older adults often experience isolation, which leads to poor nutrition habits and negative health trends. As patient advocates, nurses must gain understanding of federal and local nutrition assistance programs and implement timely referrals for their at-risk patients.

Alcohol Use

Because alcohol is high in calories and low in nutrient value, it can negatively impact nutritional health even when consumed in acceptable levels. The use of alcohol can increase the risk of chronic disease and injury. Alcohol consumption is linked to elevated triglycerides. Excessive use of alcohol can lead to chronic nutrient deficiencies due to poor absorption of nutrients, fluid imbalance, gastrointestinal disorders, and liver disease. According to Healthy People 2030, binge drinking (consuming four or more drinks per day for females or five or more drinks per day for males) is a significant problem in the United States (CDC, 2022). The USDA recommends that males limit consumption to two drinks per day and females to one drink per day.

Overuse of Supplements

Supplementation of macronutrients and micronutrients has become increasingly popular due in part to marketing and fitness claims as well as easy access to over-the-counter supplements. Supplements are pills, capsules, and liquids that contain vitamins, minerals, amino acids, or other nutrients. The U.S. government does not require manufacturers of dietary supplements to prove their safety or efficacy, and thus the industry is poorly regulated. Even when supplements are accurately labeled and safely produced, their overuse can lead to toxicities, particularly in fat-soluble vitamins such as vitamin A and vitamin D. Large doses of vitamin C, vitamin B6, and niacin can also lead to toxicities. Performance-enhancing dietary supplements contain amino acids that in excess can cause liver and kidney impairment. It is important for nurses to be familiar with the RDI, RDA, and other standard nutrient recommendations and know how to assess for potential toxicities in patients taking supplements.

Clinical Safety and Procedures (QSEN)

QSEN Competency: Evidence-Based Practice (EBP)

Definition: Integrate best current evidence with clinical expertise and patient/family preferences and values for delivery of optimal health care.

Knowledge: Explain the role of evidence in determining best clinical practice

Action: It is important for the nurse to ask the patient about any over-the-counter supplements they may be taking. Many patients do not realize that certain supplements can interact with prescription medication or that to much supplement can cause toxicity. Completing a comprehensive health assessment ensures the nurse is providing evidence-based practice.


Some medications enhance metabolic processes and impact nutritional status in a variety of ways. For example, exogenous insulin brings needed glucose into body cells. Antiglycemic medications, such as sulfonylureas and bigaunides, assist in improving insulin sensitivity, thus improving utilization of blood glucose by the cells in the body. Thyroid hormone maintains thyroid function, which sets the body’s metabolic rate. Other medications affect gastric function by lowering levels of acid production. Still other medications, such as psyllium and glycolax, alter absorption of nutrients and water in the gut. Statin drugs lower lipids levels. It is important to know how medications are used within the body and how they directly influence metabolic processes.

Many medications have an indirect effect on nutritional status. For example, diuretics are used to increase elimination of water and thus will affect body water levels as well as sodium and potassium balance. Medications with gastric upset as a side effect can decrease nutrient intake and absorption. Some psychotropic medications interfere with appetite, leading to either weight gain or weight loss, depending on the drug. Nurses must be familiar with the side effects of all drugs administered to patients under their care, anticipating long-term effects on nutritional status.

Some nutrients interfere with the mechanism of action of different drugs. For example, vitamin K, found in green leafy vegetables, can decrease the effectiveness of some anticoagulants. In contrast, some drugs should be taken with food to increase absorption. For example, vitamin C improves the absorption of iron. The pharmacokinetics of a drug—the study of the drug’s absorption, metabolism, and distribution within the body—determine the probability of a food-drug interaction. Food and drug interactions can cause deficiencies or toxicities depending on the drug and the food. Nurses must always review administration requirements for each drug, noting whether the drug should be taken with or without food.

Patient Conversations

Educating a Patient About Medications Before Discharge

Scenario: The nurse is discharging his patient and reviewing the discharge paperwork with her. He notices that the patient is prescribed warfarin, a new medication that she will have to continue to take at home after discharge.

Nurse: Okay, Ms. Embiid, while in the hospital you’ve been taking warfarin. Do you know why you were taking this?

Patient: Oh, yes. It’s to keep my blood from forming a clot, right?

Nurse: That’s right. You’ll have to continue to take this medication at home, and follow up with your doctor in two weeks. Do you know how to take this medication?

Patient: Well, I’ve been taking it at night here, so I guess I’ll take it at night at home, too.

Nurse: That’s right. The best way to take this medication is to take it at the same time every night. It’s also very important to avoid cranberry juice and grapefruit juice and try to maintain the same level of vitamin K consumption every week.

Patient: Really? Why?

Nurse: Certain foods, such as cranberries and grapefruit, can actually increase the levels of warfarin absorbed by your body. High doses of vitamin K, found in green leafy vegetables, can decrease the effectiveness of warfarin. It’s very important to maintain a consistent diet and not make any major changes without checking with your doctor.

Patient: Thanks for letting me know! I’ll be sure to monitor what I eat while on warfarin.

Psychological Factors

Physiological factors, such as growth and development, health status, and medication use, have a direct effect on nutritional status within the body. Psychological factors can influence nutritional status as well. Emotional well-being is often closely associated with food preferences and intake. Self-image impacts nutritional well-being. Cultural trends in beauty and health provide context for self-image and give meaning to food and dietary traditions. Conversely, overall nutrition can have a significant impact on psychological well-being.

Food Meaning

Nutrition is a basic necessity of life. Maslow’s hierarchy of needs (Figure 1.6) lists food as an essential physiological need. It is important to note, however, that food consumption is highly influenced by cultural and environmental factors that have a profound effect on psychological well-being. Thus, food to most people is more than a nutrient. Food is tied to family traditions and celebrations in life. Americans traditionally celebrate Thanksgiving with turkey and pumpkin pie. Many Italian Americans celebrate the Feast of Seven Fishes on Christmas Eve, and Jewish tradition serves challah bread at the Sabbath and potato latkes at Hanukkah. Similarly, vegans avoid meat and other animal products due to personal beliefs related to animal cruelty and exploitation. Many cultures have food traditions that transcend nutritional science, giving food meaning beyond its chemical composition.

Emotional responses are invoked when food meaning goes beyond mere nutrition. Most celebrations that involve food evoke feelings of comfort, happiness, and belonging. Memories, both good and bad, are often tied to the sight and smell of specific foods. Associations with sadness and grief can lead to food aversions, while foods tied to comfort can lead to food excesses as the desire to re-create moments of comfort and celebration override judgment. This can lead to binge eating and obesity. It is important for nurses to identify and reinforce healthy patterns of eating and recognize nutritional risks related to emotional eating habits.


Nutritional status is tied to weight trends, weight trends are tied to body image, and body image is tied to self-image. A person’s body image is the perception that person has about their physical body, including any feelings associated with that perception, whereas self-image is broader, encompassing feelings about one’s whole self. Individuals who maintain a healthy body weight are more likely to have a positive self-image—particularly given cultural norms, reinforced by media, that stigmatize bodies perceived to be over- or underweight. Distorted perceptions of body image can lead to severe eating disorders, such as anorexia nervosa and bulimia.


As stated earlier, food often evokes an emotional response. It can provide feelings of comfort and belonging or feelings of sadness and grief. It is easy for food to become an emotional outlet for psychological discomfort, especially when the foods consumed promote feelings of comfort and belonging. Emotional eating is common among individuals who are depressed or stressed as they seek emotional responses they find lacking elsewhere in their life. The consumption of “comfort foods” is an emotional response to stress and is common among most individuals. When the dietary pattern includes a high degree of emotional eating, negative outcomes, such as binge eating and overeating that leads to obesity, are more likely to occur. It is important to assess the underlying emotional state of individuals experiencing nutritional impairment. A holistic approach to nursing care is needed.

Unfolding Case Study

Unfolding Case Study #3: Part 5

Refer back to Unfolding Case Study #3: Part 4 to review the patient data.

Nursing Notes 1300:
While collecting the patient’s weight, she expresses concern about her weight. She states, “I know I’m not at a healthy weight, but it’s just so hard to eat healthy. Healthy food is so expensive.”
Prioritize hypotheses: What factors may be contributing to the patient’s obesity?
Generate solutions: What steps should the nurse take next to address the patient’s obesity?

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