Chapter 8 - Nutritional Disorders Flashcards
(187 cards)
0
Q
What is the most important factor determining the daily energy expenditure?
A
BMR most important factor determining DEE
1
Q
Define recommended dietary allowance.
A
RDA: optimal dietary intake of nutrients for good health
2
Q
What does BMR energy support?
A
BMR energy supports involuntary activities
3
Q
What controls the BMR?
A
Thyroid hormones control the BMR
4
Q
What is the most important factor affecting the BMR?
A
Lean body mass most important factor affecting BMR
5
Q
How is the BMR affected in thyroid disorders?
A
BMR: ↓hypothyroidism, ↑hyperthyroidism
6
Q
What is the thermic effect of foods?
A
Thermic effect of foods: energy expended in response to eating a meal
7
Q
What do mature RBCs only use for fuel?
A
Mature RBCs only use glucose for fuel
8
Q
Where does CHO digestion begin? How much energy is produced by complete oxidation of glucose?
A
CHO digestion: begins in the mouth; 4 kcal/g
9
Q
What does amylase do?
A
Amylase breaks down polysaccharides → disaccharides (lactose, maltose, sucrose)
10
Q
What are the disaccharidases?
A
Disaccharidases: lactase, maltase, sucrase
11
Q
What are the substrates and products of the disaccharidases?
A
Lactase converts lactose to galactose + glucose
Maltase converts maltose to two glucoses
Sucrase converts sucrose to fructose + glucose
12
Q
What do the disaccharidases produce?
A
Disaccharidases: produce glucose, galactose, fructose
13
Q
Amino acids are substrates for what?
A
AAs: substrates for gluconeogenesis
14
Q
What do transaminases do?
A
Transaminases remove amine groups from AAs to produce an α-ketoacid
15
Q
Describe the reactions performed by AST and ALT.
A
AST converts alanine to pyruvate; ALT converts aspartate to OAA
16
Q
Where does protein digestion begin?
A
Protein digestion begins in stomach
17
Q
How does HCl digest protein?
A
HCl cleaves pepsinogen into pepsin
18
Q
What does pepsin do?
A
Pepsin cleaves proteins into polypeptides
19
Q
What do pancreatic proteases do?
A
Pancreatic proteases hydrolyze polypeptides to release AAs
20
Q
What do AAs require for reabsorption?
A
AAs require functioning villi for reabsorption
21
Q
What is a triglyceride?
A
TG major dietary lipid
22
Q
FAs are the major energy source for what tissues?
A
FAs major energy source for all tissues except RBCs and brain
23
Q
What are two plant sources of monosaturated fats?
A
Monounsaturated fats: olive oil, canola oil
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What are two plant sources of polysaturated fats?
Polyunsaturated fats: soybean oil and corn oil
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What are two plant sources of saturated fats?
Saturated fats: coconut oil, palm oil
26
Animal fats from adipose are what?
Animal fats from adipose are saturated
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Animal fats from muscles/organs are what?
Animal fats from muscle/organs are polyunsaturated and monounsaturated
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Name two essential fatty acids.
Essential FAs: linolenic (ω-3), linoleic (ω-6)
29
What is linoleic acid (ω-6) is required for?
Linoleic acid (ω-6) is required for arachidonic acid synthesis
30
What are the clinical findings associated with essential fatty acid deficiency?
↓Essential FAs: scaly dermatitis, hair loss, poor wound healing
31
Where does fat digestion begin?
Fat digestion begins in small intestine
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What does pancreatic lipase do?
Pancreatic lipase hydrolyzes TGs to MGs and FAs
33
What do bile salts do?
Bile salts form micelles containing MGs, FAs, fat-soluble vitamins, CH esters
34
What does malabsorption of fats result in?
Malabsorption of fats produces fat soluble–vitamin deficiencies
35
Describe the process of fat digestion.
Fat digestion: pancreatic enzymes → bile salts/acids → intestinal cells (chylomicrons)
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Describe the formation of chylomicrons.
Intestinal cells package resynthesized TG into chylomicrons
37
What is ApoB48 required for?
ApoB48 required for formation/secretion chylomicrons
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What do chylomicrons contain?
Chylomicrons contain diet-derived TGs
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How much energy does complete oxidation of FAs produce?
Complete oxidation FAs produces 9 kcal/g
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Malnutrition best correlates with what?
Malnutrition correlates best with BMI
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What is the BMI equation?
BMI = weight in kg/height in m2
42
What is protein-energy malnutrition defined as?
PEM is defined as a BMI <16 kg/m2
43
How are body fat stores evaluated?
Body fat stores: skinfold thickness, density, conductivity, DEXA
44
How are somatic protein stores in skeletal muscle evaluated?
Somatic protein stores in skeletal muscle evaluated with mid-arm circumference
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How are visceral protein stores evaluated?
Visceral protein stores evaluated with serum albumin/transferrin
46
What is kwashiorkor?
Kwashiorkor: CHO intake > protein intake; total calories normal
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How are visceral protein stores affected in kwashiorkor?
↓Visceral protein; ↓serum albumin/transferrin
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What does excess carbohydrate intake spare in kwashiorkor?
Excess CHO intake spares protein breakdown as energy source
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How is plasma oncotic pressure affected in kwashiorkor? What clinical findings result from this effect?
Pitting edema/ascites characteristic of kwashiorkor; ↓plasma oncotic pressure
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How are apoB and VLDL levels affected in kwashiorkor? These changes result in what clinical finding?
Fatty liver due to ↓apoB synthesis and ↑VLDL synthesis
51
What is the cause of diarrhea in kwashiorkor?
Diarrhea: loss of villi/disaccharidases; parasitic infections
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Describe the features of the anemia present in kwashiorkor.
Anemia multifactorial: RBC hypoplasia; iron/folic acid/vitamin B12 deficiencies
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Describe the cutaneous changes in kwashiorkor.
Flaky paint dermatitis; flag sign in hair
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Describe how the immune system is affected in kwashiorkor.
Defective CMI: parasitic infections
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Describe the psychological disturbances in kwashiorkor.
Poor prognosis due to apathy, listlessness, and lack of appetite
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What is marasmus?
Marasmus: total calorie deprivation; ↓protein/CHOs
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What is common in marasmus?
Extreme muscle wasting is common in marasmus
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How are fat stores affected in marasmus?
Loss subcutaneous fat
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Secondary PEM is most common in whom?
2° PEM is most common in the elderly population
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What are the clinical findings in secondary PEM?
Depletion subcutaneous fat/skeletal muscle; ankle/sacral edema; multiple nutrient deficiencies
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What is anorexia nervosa?
Anorexia nervosa: self-induced starvation; 2° PEM
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How do patients with anorexia nervosa view themselves?
Distorted body image
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How does the death rate compare to that of other psychiatric disorders?
Highest death rate among all psychiatric disorders
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Use of what is common in anorexia nervosa?
Laxative abuse common; danger of laxative bowel and hypokalemia
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Who is affected by anorexia nervosa?
MC in teenage girls and young women
| Common in athletics, modeling, ballet; history of sexual abuse common
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How are GnRH levels affected in anorexia nervosa? What results from this effect?
2° Amenorrhea due to ↓GnRH
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How are FSH, LH, and estradiol levels affected in anorexia nervosa?
↓FSH, LH, estradiol
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How is the bone affected in anorexia nervosa?
Osteoporosis due to hypoestrinism
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What is euthyroid sick syndrome?
Euthyroid sick syndrome: bradycardia, hypotension, cold intolerance, skin/nail changes
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What are the cardiovascular findings in anorexia nervosa?
Peripheral edema; ↑risk cardiac arrhythmias, sudden death
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What are the laboratory findings in anorexia nervosa?
↓Serum GnRH, estradiol, FSH, LH
| ↑Growth hormone, cortisol (stress hormones)
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What is the most common cause of death in patients with anorexia nervosa?
MCC death is ventricular arrhythmia due to hypokalemia
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What is bulimia nervosa?
Bulimia nervosa: bingeing with self-induced vomiting
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What is the epidemiology of bulimia nervosa?
Female dominant; more common than anorexia nervosa
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What are the complications of vomiting in bulimia nervosa?
Eroded enamel, parotid/salivary gland swelling; hematemesis (tear/rupture distal esophagus)
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What are the electrolyte abnormalities from vomiting in bulimia nervosa?
Vomiting: hyponatremia/hypokalemia; metabolic alkalosis
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What are the electrolyte abnormalities from laxative abuse in bulimia nervosa?
Laxative abuse: hyponatremia/hypokalemia; metabolic acidosis; hypomagnesemia, hypocalcemia
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What is the most common cause of death in patients with bulimia nervosa?
MCC death is ventricular arrhythmia due to hypokalemia
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How is obesity defined?
Obesity = BMI >30 kg/m2
80
Describe the prevalence of obesity in terms of age.
Prevalence increases with age; declines after sixth decade
81
Obesity is an independent risk factor for what?
Independent risk factor for ischemic heart disease
82
Obesity is a major preventable cause of what in the U.S.?
Major preventable cause of death/disability in United States
83
What are the cutaneous findings in anorexia nervosa?
Dry skin, brittle nails, sparse scalp hair, ↑lanugo hair on face, yellow skin (↑carotene)
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What is the most important risk factor for morbidity/mortality from obesity?
Abdominal visceral fat most important risk factor for morbidity/mortality
85
What are the key hypothalamic centers?
Key hypothalamic centers: arcuate nucleus, paraventricular nuclei
86
What is leptin? What is the effect of increased leptin levels?
Leptin: hormone secreted by adipose ↑Leptin → ↓food intake, ↑energy expenditure
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What is ghrelin? What is the effect of increased ghrelin levels?
Ghrelin: hormone secreted by stomach
| ↑Ghrelin → ↑food intake, ↓energy expenditure
88
What is the effect of decreased or dysfunction of leptin?
↓/dysfunction leptin: ghrelin unopposed (↑appetite, ↓energy expenditure)
89
What is the effect of insulin on TGs?
Insulin normally increases TG in adipose
90
How are insulin levels and TGs stores affected in type II DM?
Type 2 DM: hyperinsulinemia ↑TG stores in adipose
91
What is reabsorption of fat-soluble vitamins associated with?
Reabsorption of fat-soluble vitamins is associated with micelle formation for reabsorption of fats
92
How does malabsorption of fat affect vitamin levels?
Malabsorption of fat leads to fat-soluble vitamin deficiencies
93
Vitamin toxicities are more common with what vitamins?
Vitamin toxicities: fat-soluble > water-soluble
94
What are the water-soluble vitamins used for?
Water-soluble vitamins cofactors for enzyme reactions (except folic acid)
95
What are the clinical findings in β-carotenemia?
β-carotenemia: yellow skin, white sclera
96
Where is the main storage site for vitamin A and how is it stored?
Liver is main storage site; stored as retinyl esters
97
Why is retinoic acid important?
Retinoic acid: important in differentiation of epithelial tissue; growth/reproduction
98
What is retinal and why is it important?
Oxidation product of retinol → used to synthesize rhodopsin → important in reduced light
99
What are the functions of vitamin A?
Normal vision in reduced light (night vision)
Differentiation of mucus-secreting epithelium
Stimulates immune system
Stimulates growth/reproduction
100
What are the causes of vitamin A deficiency?
Deficiency: diet lacking yellow/green vegetables; fat malabsorption
101
What are the causes of vitamin A toxicity?
Toxicity: consuming liver from polar bears, whales, sharks, tuna
Toxicity: megadoses of vitamin A and Rx of acne with isotretinoin
102
What are the clinical uses of vitamin A?
Clinical Rx: acne, APL, measles, hairy leukoplakia, retinitis pigmentosa
103
What is preformed vitamin D in plants called and what is it converted to?
Ergocalciferol (plants) → cholecalciferol (vitamin D3)
104
Describe the endogenous synthesis of vitamin D in the skin.
Photoconversion 7-dehydrocholesterol → cholecalciferol; 90% endogenously derived vitamin D
105
Where does 25-hydroxylation of vitamin D occur? What enzyme performs this reaction?
25-Hydroxylation in the liver CYP-450 system
106
What does PTH synthesize?
PTH synthesizes 1-α-hydroxylase in proximal tubules
107
Where does 1-α-hydroxylation of vitamin D occur?
1-α-Hydroxylation in proximal tubules
108
What is the active form of vitamin D?
1,25-(OH)2-D: active form of vitamin D
109
What mediates feedback control of calcitriol synthesis?
Feedback control of calcitriol synthesis is calcium-mediated
110
Describe the effect of decreased serum calcium on calcitriol synthesis.
↓Serum Ca2+ → ↑synthesis PTH → ↑synthesis 1-α-OHase → ↑synthesis calcitriol
111
Describe the effect of increased serum calcium on calcitriol synthesis.
↑Serum Ca2+ → ↓synthesis PTH → ↓synthesis 1-α-OHase → ↓synthesis calcitriol
112
What are the functions of calcitriol?
Calcitriol: bone mineralization; maintain serum Ca2+/PO43−
Calcitriol: stimulates macrophage stem cell conversion → osteoclasts
113
Where are vitamin D receptors located?
Vitamin D receptors on osteoblasts/chondrocytes
114
What does alkaline phosphatase do?
Alkaline phosphatase dephosphorylates pyrophosphate, an inhibitor of bone mineralization
115
What is osteocalcin?
Osteocalcin is calcium-binding protein; important in bone mineralization
116
What is the most common cause of vitamin D deficiency?
Renal failure MCC vitamin D deficiency
117
What is the effect of inadequate sun exposure on vitamin D levels?
Inadequate sun exposure → ↓photoconversion to vitamin D3
118
What is the effect of fat malabsorption on vitamin D levels?
Fat malabsorption → ↓micelle formation → ↓vitamin D/fat reabsorption
119
What is the effect of chronic liver disease on vitamin D levels?
Chronic liver disease→↓25-hydroxylation
120
What is the effect of induction of the liver CYP-450 system on vitamin D levels?
Induction liver CYP-450 system → ↑metabolism 25-(OH)-D → inactive metabolite
121
What are two causes of vitamin D toxicity?
Toxicity: megadoses, sarcoidosis
122
What are the functions of vitamin E?
Vitamin E: cell membrane antioxidant; prevents LDL oxidation
123
What are the causes of vitamin E deficiency?
Vitamin E deficiency: fat malabsorption cystic fibrosis, abetalipoproteinemia
124
What is a cause of vitamin E toxicity?
Vitamin E toxicity: megadoses vitamin E
125
The majority of vitamin K is synthesized by what?
Vitamin K: majority synthesized by colonic bacteria
126
What enzyme activates vitamin K?
Epoxide reductase activates vitamin K
127
What enzyme is inhibited by coumarin derivatives?
Coumarin derivatives inhibit epoxide reductase
128
What does vitamin K do?
Vitamin K: γ-carboxylates II, VII, IX, X; protein C and S
| γ-Carboxylation activates vitamin K–dependent factors; allows them to bind calcium in fibrin clot formation
129
What is the most common cause of vitamin K deficiency in a hospitalized patient?
Broad-spectrum antibiotics: MCC vitamin K deficiency in hospital
130
When does bacterial colonization of the newborn bowel occur?
Newborns: lack bacterial colonization bowel until 5–6 days old
131
How are newborns treated for vitamin K deficiency?
Newborns must receive IM injection of vitamin K
132
Which fat-soluble vitamin is lacking in breast milk?
Breast milk lacks vitamin K
133
How do coumarin derivatives and cirrhosis affect vitamin K activation?
Coumarin derivatives/cirrhosis decrease epoxide reductase
134
What is the effect of fat malabsorption on vitamin levels?
Fat malabsorption ↓intestinal reabsorption fat-soluble vitamins
135
What is thiamine important in?
Thiamine: important in ATP synthesis
136
What are the functions of thiamine?
Thiamine: pyruvate dehydrogenase converts pyruvate to acetyl CoA
Thiamine: transketolase reactions
137
What is the most common cause of thiamine deficiency in the U.S.?
Chronic alcoholism MCC thiamine deficiency in United States
138
What is FAD used for?
FAD is cofactor for succinate dehydrogenase conversion of succinate to fumarate in CAC
139
Where is FMN located and what is it important in?
FMN in ETC; important in ATP synthesis
140
What are the active forms of niacin?
Niacin: NAD/NADP cofactors in oxidation-reduction reactions
141
What type of reactions does NAD+ participate in?
NAD+ oxidation-reduction reactions are catabolic
142
What type of reactions does NADP+ participate in?
NADP+ oxidation-reduction reactions are anabolic
143
Corn-based diets are deficient in what?
Corn-based diets: deficient in tryptophan and niacin
144
Tryptophan is used to synthesize what?
Tryptophan used to synthesize niacin/serotonin
145
What are the causes of tryptophan deficiency?
Tryptophan deficiency: corn-based diet, Hartnup disease, carcinoid syndrome
146
What are the three Ds of pellagra?
Three Ds of pellagra: dermatitis, diarrhea, dementia
147
What are the functions of pyridoxine?
Pyridoxine: heme synthesis, transamination, neurotransmitters
148
What are the causes of pyridoxine deficiency?
Pyridoxine deficiency: isoniazid (MCC), goat milk, chronic alcoholism
149
What is the function of biotin?
Biotin: cofactor in carboxylase reactions
150
Give two examples of carboxylation reactions.
Carboxylase reactions: pyruvate to OAA, propionyl CoA to methylmalonyl CoA
151
What are the causes of biotin deficiency?
Biotin deficiency: eating raw eggs; antibiotics
152
What are the sources of vitamin C?
Present in fruits/vegetables, liver, fish, milk
153
What does vitamin C do?
Hydroxylates proline and lysine in RER of fibroblasts
154
What does lysyl oxidase do?
Lysyl oxidase forms cross-links between hydroxylation sites on tropocollagen
155
What is responsible for the tensile strength of collagen?
Cross-linking tropocollagen molecules increases tensile strength
156
What is scurvy?
Scurvy: weak tensile strength of collagen; hemorrhage, poor wound healing
Scurvy: ↓synthesis structurally weak osteoid in bone; bone fragility, joint pain
157
Describe the antioxidant properties of vitamin C.
Antioxidant: neutralizes hydroxyl FRs, regenerates vitamin E
158
What does vitamin C do to iron?
Reduces nonheme iron (Fe3+) to heme iron (Fe2+)
159
What is the heme iron state necessary for?
Heme iron (Fe2+) state: necessary for duodenal reabsorption; binds O2 in RBCs
160
How does vitamin C affect tetrahydrofolate?
Keeps tetrahydrofolate (FH4) in reduced state; carrier for single-carbon functional groups
161
What is the role of vitamin C in catecholamine synthesis?
Ascorbic acid: cofactor in conversion of dopamine to norepinephrine
162
What are the causes of vitamin C deficiency?
Deficiency: diets lacking fruits/vegetables, smoking
163
What is zinc a cofactor for?
Cofactor for metalloenzymes (e.g., collagenase)
164
Why is zinc important in children?
Children: growth, spermatogenesis
165
What are the causes of zinc deficiency?
Deficiency: alcoholism, diabetes, chronic diarrhea, acrodermatitis enteropathica
166
What are the functions of copper?
Cofactor for ferroxidase, lysyl oxidase, tyrosinase
167
What is the most common cause of copper deficiency?
MCC deficiency: TPN
168
What is Wilson disease?
Wilson disease: defect in copper elimination in bile; ↓ceruloplasmin (binding protein)
169
What are the clinical findings in Wilson disease?
Wilson disease: liver disease, Kayser-Fleischer ring, parkinsonism, dementia
170
What are the lab findings in Wilson disease?
↓Total serum copper, ceruloplasmin; ↑serum/urine free copper
171
What is the function of iodine?
Iodine used to synthesize thyroid hormone
172
What is the cause of iodine deficiency?
Deficiency: ↓intake iodized table salt
173
What are the functions of chromium?
Component of glucose tolerance factor to maintain normal serum glucose
Cofactor for insulin: facilitates binding of glucose to muscle/adipose
174
Chromium deficiency is most often due to what?
Deficiency most often due to TPN
175
What is the function of selenium?
Selenium is an antioxidant
176
Selenium deficiency is most often due to what?
Deficiency usually due to TPN
177
What are the functions of fluoride?
Functions: part of calcium hydroxyapatite in bone/teeth; prevent dental caries
178
What is the cause of fluoride deficiency?
Deficiency: inadequate intake fluoridated water
179
What are the clinical findings of fluoride excess?
Excess: chalky tooth deposits, calcification of ligaments, risk for bone fracture
180
What are the types of dietary fiber?
Fiber types: insoluble, soluble
181
What are the features of insoluble fiber?
Insoluble fiber: nonfermentable, ↑stool bulk, softens stool
182
What are the features of soluble fiber?
Soluble fiber: fermentable, softens stool, ↑fecal bacterial mass
183
An increase in fiber may reduce the risk of what?
↑Fiber may reduce risk for endometrial, breast, colon cancer
| ↑Fiber: ↓risk for sigmoid diverticulosis by preventing constipation
184
How does soluble fiber decrease the risk of heart disease?
Soluble fiber lowers serum cholesterol
185
What can be treated by sodium-restriction?
Sodium restriction: hypertension, heart failure, chronic liver/kidney disease
186
What can be treated by protein-restriction?
Protein-restriction: Rx chronic renal failure, cirrhosis
