Nutrition Deck Flashcards
When is measurement of energy expenditure by indirect calorimetry clinically useful?
To accurately estimate energy needs of hospitalized patients who need nutrition support and are at high risk of stress hypermetabolism (severe burns or trauma) or have severe obesity.
What effect does fever have on energy expenditure and therefore caloric requirements?
Basal metabolic rate increases 10-12% with each °C increase in body temperature.
Oxidization of what macronutrient produces the highest RQ (or the most CO2 per O2 used)?
Carbohydrates. By definition, carbohydrates are made of hydrates carbons (CH2O)n. Therefore, they require the least amount of O2 to fully oxidize to CO2 (and produce the least amount of energy).
How is measurement of the Respiratory Quotient (RQ) helpful in the clinical environment?
It indicates what combination of macronutrients is being oxidized. For example, an RQ of 0.7 indicates that a patient is almost entirely oxidizing fats, which occurs if their metabolic needs are not being appropriately met.
Why does measurement of O2 usage provide a reliable estimate of energy expenditure?
About 90% of the O2 utilized by the body is used to drive nutrient oxidation and ATP production. In other words, the O2 is a substrate for Complex IV (Cytochrome c oxidase) of the electron transport chain, which is the basis of our metabolic rate and allows for all of our energy expenditure
The smallest contributor to Total Energy Expenditure (TEE) in a healthy child is most commonly:
A. Basal energy expenditure
B. Growth
C. Physical activity
D. Thermal effect of food
B. Growth
How can a measurement of O2 utilization be useful in the clinical setting?
A. Demonstrates whether a patient has adequate calories for healing.
B. Demonstrates whether a patient is breathing well.
C. Indicates that a patient is ready to move from parental nutrition to enteral feeding.
D. Provides a reliable estimate of a patient’s energy expenditure
D. Provides a reliable estimate of a patient’s energy expenditure
About 90% of O2 used is for the oxidation of macronutrients and production of ATP, and therefore O2 usage allows one to reliably estimate metabolic rate (energy expenditure).
What information does the respiratory quotient (CO2 produced/O2 consumed) provide?
A. Indication that a patient is ready to move from parental nutrition to enteral feeding.
B. Mix of the macronutrient fuels being utilized
C. Reliable estimate of a patient’s energy expenditure
D. Thermic effect of food
B. Mix of the macronutrient fuels being utilized
For a person with a typical basal metabolic rate (BMR) of 1400 kcal/day and body temperature of 37 °C, how would a fever of 39.0°C affect their BMR?
A. -280 kcal/day
B. -140 kcal/day
C. no major impact
D. +140 kcal/day
E. +280 kcal/day
E. +280 kcal/day
Which of the following is a significant complication of enteral feeding?
A. Aspiration pneumonia
B. Ketoacidosis
C. Liver damage
D. Pancreatic atrophy
E. Sepsis
A. Aspiration pneumonia
Enteral feeding can lead to reflux of stomach contents into the lungs, which can lead to aspiration pneumonia.
A 73-year-old woman is admitted to the rehab unit for evaluation after suffering a cerebral infarction. She is alert and oriented but unable to swallow. How should she be fed?
A. Orally
B. Enterally
C. Parentally
D. Both enterally and parentally
B. Enterally
She has normal bowel function, but cannot maintain adequate oral intake. Therefore, she should be fed via a GI tube.
A 38-year old man was admitted following a major car accident 5 days ago. He suffered severe head and neck injuries, several broken bones and numerous lacerations. He has undergone 3 surgeries and has not yet regained consciousness. How should he most likely be fed?
A. Orally
B. Enterally
C. Parentally
D. Both enterally and parentally
D. Both enterally and parentally
His GI tract is intact and his nutritional needs are most likely very high due to the extent of his injuries. Therefore, following a full nutritional assessment, he will most likely be fed both enterally (to maintain his GI tract and prevent atrophy of the mucosa) and parentally to ensure adequate nutrition to fully support healing.
Mr. Parsons, an 81-year-old man with a history of type 2 diabetes, is admitted to the ICU following a heart attack. He will undergo pacemaker insertion surgery tomorrow, and later this week will have cardiac catheterization to determine the need for a coronary artery bypass graft. He has been NPO (nil per os = nothing by mouth) for the past 4 days due to procedures, and with upcoming surgery, his status remains NPO. Concerned about his nutritional status, you interview his family and review his labs.
He has had a steady weight gain over the past three years, has obesity, and has had an adequate diet. His laboratory values that were checked indicate adequate protein status. He is likely to remain NPO after surgery. Which of the following actions is most appropriate to take?
A. None, his IV dextrose provides the energy he requires
B. Order a clear liquid diet
C. Order a nutrition consult
D. Start him on enteral nutrition
E. Start him on parenteral nutrition
C. Order a nutrition consult
Though he is well nourished now, he is at risk for malnutrition due to NPO status. Not eating for over 4 days is especially significant for people with marginal nutritional status. All patients in this situation should be monitored. If nutritional status is already compromised, beginning early (pre-operative) nutrition support is appropriate. If a patient with good baseline nutritional status remains NPO for more than 5 to 7 days, survival and recovery are best with careful nutritional assessment and initiation of nutritional support (oral, enteral, or parenteral) as indicated.
One week later, Mr. Parsons is still in the intensive care unit following a coronary artery bypass graft operation. His post-operative course was complicated by infection and ileus. His transthyretin has decreased from his admission level. What should you do?
A. Nothing, he has adequate energy and protein stores
B. Start him on parenteral nutrition with simultaneous slow infusion of enteral feeding.
C. Monitor his nutrition and order a nutrition consult if his nutrition status declines.
D. Start him on parenteral feeding only.
E. Place a tube and begin enteral feeding only.
B. Start him on parenteral nutrition with simultaneous slow infusion of enteral feeding.
Since this patient’s nutritional status is already compromised, beginning early enteral nutrition support is appropriate. You could not feed him solely by enteral means as his gastrointestinal tract is not functioning normally. Feeding him parenterally to meet his nutritional requirements while stimulating his intestines with a small amount of enteral formula is the best option. Remember, use the gut if possible. You do want to continue to monitor his nutritional status, but it is important to initiate adequate nutrition support before his nutritional status declines further. And, yes, you would also probably order a nutrition consult.
If Mr. Parsons’ nutritional support is delayed, evidence indicates that which of the following will likely result?
A. Dehydration
B. Essential fatty acid deficiency
C. Hair loss
D. Hepatomegaly
E. Increased hospital stay
E. Increased hospital stay
Early and appropriate nutrition support is associated with decreased length of hospital stay. Acute complications of malnutrition include impaired wound healing, increased incidence of infection, and edema. Dehydration would only occur with restriction of fluids or increased fluid loss; this is why fluid intake and output are closely monitored in the ICU. Hepatomegaly, hair loss, and essential fatty acid deficiency are long-term complications of severe malnutrition.
A 14-year-old girl was admitted to the hospital with purpura, edema and generalized weakness. On physical examination she was found to be emaciated, weighing only 28 kg (BMI of 14.1 kg/m2). Her parents indicated that she had been suffering from anorexia for the past 1.5 years. Why will it be important to slowly and carefully provide nutrition support, while carefully monitoring her blood chemistry?
A. Rapid refeeding can cause severe nausea and vomiting
B. Rapid refeeding can sepsis due to intestinal atrophy
C. Rapid refeeding can cause electrolyte imbalances
C. Rapid refeeding can cause electrolyte imbalances
Refeeding syndrome is characterized by shifts of potassium, magnesium, and phosphorus moving into cells upon a sudden influx of glucose. If the change from starvation metabolism to abundant glucose occurs too quickly, a dangerous electrolyte imbalance can occur.
Tyler Gordon, a 10-year-old boy, suffered an accidental gunshot wound to the abdomen several days ago. He was normally nourished prior to his accident; ht: 132 cm, wt: 30 kg, BMI 17.2 (normal for age). During surgery 70% of his small bowel was resected, he was given a partial colectomy and his stomach, duodenum and vena cava were repaired. What form of nutritional support is most appropriate at this time?
A. Continue present regimen of dextrose in saline
B. Feed him when he is able to eat again
C. Start feeding him by vein and J-tube.
C. Start feeding him by vein and J-tube.
Supplemental nutritional support should be initiated in patients who are expected to have inadequate oral intake over 7 to 14 days.
A 57-year-old male was admitted to the hospital with severe confusion. He had a severe memory defect, ataxia, upbeat nystagmus, double vision, and signs of peripheral neuropathy. He has been a heavy drinker of alcohol for over 25 years. This Patient is most likely to be deficient in which of the following?
A. Vitamin B1
B. Medium Chain acyl CoA Dehydrogenase
C.Glucose-6-Phosphatase
D. Glucose-6-Phosphate Dehydrogenase
E. Vitamin C
Vitamin B1 Deficiency
Thiamine deficiency is relatively common in alcoholics, often resulting in neuropathy and confusion. This is much more likely than a rare genetic defect in a metabolic enzyme, such as ornithine transcarbamoylase (urea cycle). Glucose 6-phosphatase deficiency and Medium chain acyl CoA dehydrogenase deficiency each result in fasting hypoglycemia, not neuropathy. Glucose 6-phosphate dehydrogenase deficiency results in oxidant-induced hemolysis. Vitamin C deficiency results in scurvy, characterized by blood vessel and connective tissue breakdown.
Two weeks after his accident, Tyler’s mother wants to know if she can feed him a milkshake. What sign will indicate that he is recovering enough to consider slowly increasing the enteral feeding, followed by slow oral feeding?
A. When he feels hungry
B. When bowel sounds can be heard
C. When his respiratory quotient has normalized at about 0.85
B. When bowel sounds can be heard
His intestines will be essentially paralyzed for weeks/months after his accident/surgery. Normal bowel sounds and passing of gas will indicate that his ileus is beginning to resolve. A slow increase in enteral feeding rate will likely be tried to determine how well he can tolerate the change.
What does amylase primarily digest?
Starch (into di-, tri- and small poly-saccharides of glucose)
Why are beans the musical fruit? (Why do they cause gas?)
They contain polysaccharides that we lack digestive enzymes to hydrolyze. Intestinal bacteria catabolize these polysaccharides into gases.
Which monosaccharide is most commonly malabsorbed, causing flatulence, bloating, cramping, diarrhea, and/or constipation?
Fructose. Up to 40% of people experience some amount of abdominal distress after consuming a diet high in fructose.
High FODMAP foods should be avoided by most people
A. True
B. False
B. False
Many nutritious vegetables, fruits, legumes and whole grains are high in FODMAPs, and therefore are an important part of a healthy eating pattern. However, when someone experiences irritable bowel symptoms, they are often prescribed to eat a specific restrictive diet for several weeks that is low in FODMAPs to see if their symptoms resolve; this is effective in the majority of patients. Then specific foods and food groups can be re-introduced to identify the specific problematic food(s).
Fructose malabsorption is different from hereditary fructose intolerance.
A. True
B. False
A. True
Fructose malabsorption is just what the name implies - inability to absorb all of the fructose in the small intestine. The mechanism is currently not understood and not obvious. It is a common condition, with estimates as high as 40% of people consuming a high fructose (‘typical’ American) diet. When people with this condition consume fructose they experience GI distress (gas, bloating, cramps, diarrhea, and/or constipation.)
Hereditary fructose intolerance is caused by a mutation or alteration in the gene encoding aldolase B, a metabolic enzyme found primarily in liver. This is a rare condition and causes fructose-1-phosphate to build up in hepatocytes, leading to major perturbations of liver metabolism when these people consume fructose.
Sometimes the term ‘fructose intolerance’ is used when fructose malabsorption is meant.
Inhibiting what enzyme is most important for prevention of pancreatitis?
Trypsin. Once trypsin becomes active, it can cleave and activate more trypsinogens as well as activating the other pancreatic proteases and colipase (required for lipase activity).
What cells secrete intrinsic factor?
Gastric parietal cells
Why is intrinsic factor required?
To bind vitamin B12 in the small intestine after haptocorrin has been proteolyzed. Only the B12-intrinsic factor complex is absorbed in the ileum.
What is mostly absorbed in the duodenum?
- Heme iron
- Most of the absorbable non-heme iron
- Calcium
What is primarily absorbed in the duodenum and upper jejunem?
- Iron
- Calcium
- Folate
- Most B vitamins
A patient experiences gas and bloating after consuming foods/drink sweetened with sugar (cane or beet), but has no trouble with high-fructose corn syrup-sweetened foods/drink. This person most likely has a deficiency in:
A. A disaccharidase
B. GLUT2
C. GLUT5
D. Pancreatic amylase
E. SGLT1
A. A disaccharidase
This patient most likely has a sucrase deficiency. Sucrase is the disaccharidase that hydrolyzes sucrose (table sugar) into glucose and fructose. Since they have no problem absorbing the monosaccharides (glucose and fructose) found in high fructose corn syrup, the three transporters listed (GLUT2, GLUT5, SGLT1) all appear to be functioning. Pancreatic amylase is important for digesting (hydrolyzing) starch into short polymers of glucose (maltose, isomaltose, trisaccharides and larger oligosaccharides, and dextrins), and that patient reports no issues related to starch intolerance.
The patient described in question 1 would most likely have a finding outside of the reference range after consuming table sugar for which clinical text?
A. Hydrogen breath test
B. Methylmalonic acid
C. Serum ferritin
D. Serum tTG IgA
E. Stool elastase-1
A. Hydrogen breath test
Undigested/unabsorbed sugars are metabolized by intestinal microbes into a variety of gases and short chain fatty acids (e.g. 3-carbon propionate, 4-carbon butyrate). Hydrogen gas is commonly measured to diagnose carbohydrate maldigestion/malabsorption. Methylmalonic acid levels rise with a vitamin B12 deficiency. Iron deficiency often results in low serum ferritin (although chronic inflammation often increases ferritin levels). Serum tTG IgA is a test for celiac disease. Low levels of elastase-1 in the stool occur during pancreatic insufficiency since elastase is one of the digestive proteases secreted from the exocrine pancreas into the small intestine.
Dietary fiber from fruits, vegetables, nuts, seeds, legumes and whole grains is an important part of a healthy diet. Which of the following is not a known role for either soluble or insoluble dietary fiber?
A. Adds bulk to stools
B. Helps neutralize the pH of the small intestine
C. Provides nutrients for gut microbes
D. Slows digestion and absorption
B. Helps neutralize the pH of the small intestine
Insoluble dietary fiber adds bulk to stools and helps prevent constipation. Soluble fibers can be metabolized by intestinal microbes, providing them with nutrients. Soluble fiber also slows digestion and absorption, helping with satiety and appropriate nutrient absorption rates. Fiber does not help neutralize the pH of the small intestine; pancreatic bicarbonate does this.
A previously active and healthy 46-year-old man presented to clinic with concerns of memory loss, ‘brain fog’, and episodes of depression and aggressive behavior. He also reported having been pulled over for drunk driving, with a breathalyzer test indicating 0.15% blood alcohol, although he swears not having a drink that day. His symptoms began shortly after he started antibiotic therapy (cephalexin 250 mg orally three times a day for 3 weeks) for a complicated traumatic thumb injury. (Case from https://bmjopengastro.bmj.com/content/6/1/e000325(opens in a new tab) ). What was the most likely effective therapy?
A. A FODMAPS diet
B. Antifungal targeting Saccharomyces species
C. Pancreatic enzyme replacement
D. Ten-days of vancomycin or fidaxomicin
C. Vitamin B12 injections
B. Antifungal targeting Saccharomyces species
This is a case of auto-brewery syndrome. The likely explanation is that the three weeks of oral antibiotics significantly disrupted the patient’s normal gut microbiota, killing off many of the bacteria and allowing fungal outgrowth. Saccharomyces, the fungal yeast used for brewing beer, likely grew to become a significant part of his microbiota and it fermented dietary fibers and carbohydrates into ethanol. Antifungal drugs are used to treat auto-brewery syndrome. A low FODMAPS diet might decrease the substrate for the yeast to ferment enough to lower the patient’s blood alcohol, but this isn’t a healthy or easy long-term diet and therefore isn’t the best choice. There is no indication that he is lacking pancreatic enzymes or vitamin B12. Ten-days of vancomycin or fidaxomicin is used to treat Clostridium difficile (C. diff), an intestinal bacterium that can overgrow after use of other antibiotics. However, C. diff is not known to produce ethanol, and instead causes diarrhea, abdominal pain and fever.
A 24-year-old woman presents with cramping, belly pain, bloating, gas, and alternating episodes of diarrhea and constipation. She is diagnosed with irritable bowel syndrome (IBS). With the guidance of the healthcare team, she begins a low FODMAP diet. Which of the following best describes the initial phase of this restrictive diet?
A. Dairy products are completely removed from the diet
B. Fruits are completely removed from the diet
C. Vegetables are completely removed from the diet
D. All dairy, fruits, vegetables, and legumes are removed from the diet
E. Some dairy, fruits and vegetables, and all legumes are removed from the diet
E. Some dairy, fruits and vegetables, and all legumes are removed from the diet
The goal of the initial phase of the low FODMAPs diet is to remove excess fructose, lactose, fructans, galactans, and polyols from the diet. In most cases of IBS, the patient’s symptoms will decrease within a few weeks. Then, usually under guidance from a dietitian, the patient begins to re-introduce only one of these groups at a time to help determine which of these components causes their symptoms. Some fruits, vegetables and dairy (a few cheeses) are low in each of the FODMAP components, while all legumes have galactans. It’s complicated, but effective.
Specific genetic variants in trypsinogen can cause it to prematurely hydrolyze the peptide bond that normally connects the inhibitory polypeptide with trypsin. What type of hereditary, chronic disease is this most likely to cause?
A. Duodenal ulcers
B. Enterocyte damage similar to celiac disease
C. Inflammatory bowel disease
D. Pancreatitis
E. Peptic ulcer disease
D. Pancreatitis
Trypsinogen is normally only activated in the lumen of the small intestine by enteropeptidase which cleaves off the inhibitory polypeptide, converting trypsinogen to trypsin. Once some active trypsin is made, it can also activate other molecules of trypsinogen and the other inactive digestive zymogens. Pancreatic trypsin inhibitor is small protein that is also produced and secreted by the exocrine pancreas to prevent premature activation of trypsin within the pancreas. However, people with specific trypsinogen variants have trypsin activating to levels that apparently overwhelm the levels of pancreatic trypsin inhibitor, and the digestive protease becomes active in the pancreas, digesting it and causing chronic pancreatitis.
What role does haptocorrin play in vitamin B12 absorption?
A. Binds and protects B12 in the stomach
B. Functions as a vitamin B12 receptor in ileum
C. Functions as an intrinsic factor receptor in the ileum
D. Stimulates gastric parietal cells to secrete intrinsic factor
A. Binds and protects B12 in the stomach
Haptocorrin is a protein secreted by salivary glands that binds to B12 in the stomach after pepsin releases the vitamin from the dietary proteins that tightly bind it. The haptocorrin is stable at low pH and is not digested by pepsin. It is thought to protect the B12 from being hydrolyzed by stomach acid. Pancreatic digestive proteases hydrolyze haptocorrin in the duodenum, releasing the B12 and allowing it to bind to intrinsic factor. The terminal ileum contains receptors for intrinsic factor, which allow the absorption of B12.
