HUMAN NUTRITION - Sheet1 Flashcards
(208 cards)
1
Q
What are the two subgroups of the vitamin E family, and how are they named?
A
The vitamin E family consists of two subgroups—tocopherols and tocotrienols. The members are designated by letters of the Greek alphabet (alpha, beta, gamma, and delta).
2
Q
Why is alpha-tocopherol the only member of the vitamin E family that is maintained in the body to meet its needs?
A
Alpha-tocopherol is the only member maintained because the other members are not converted to alpha-tocopherol in the body, and they are not recognized by its transport protein.
3
Q
What is the main action of vitamin E as an antioxidant?
A
Vitamin E’s main action is to stop the chain reaction of free radicals, preventing the production of more free radicals and protecting cell components and membranes from destruction.
4
Q
How may tocotrienols contribute to health besides preventing cancer?
A
Tocotrienols may also protect against osteoporosis, diabetes, heart disease, and neurological disorders.
5
Q
What is the primary deficiency of vitamin E associated with, and what is a classic sign of this deficiency?
A
The primary deficiency of vitamin E is associated with diseases of fat malabsorption, such as cystic fibrosis. A classic sign is erythrocyte hemolysis, seen in premature infants.
6
Q
What is the role of vitamin E in reducing the risk of heart disease?
A
Vitamin E may reduce the risk of heart disease by protecting low-density lipoproteins (LDL) against oxidation and reducing inflammation.
7
Q
What is the UL for vitamin E, and what can extremely high doses of vitamin E potentially cause?
A
The UL for vitamin E is 1000 milligrams. Extremely high doses may interfere with the blood-clotting action of vitamin K and enhance the effects of anti-clotting drugs, causing hemorrhage.
8
Q
Why is the RDA for vitamin E based only on alpha-tocopherol?
A
The RDA is based only on alpha-tocopherol because the other tocopherols and tocotrienols cannot be converted to alpha-tocopherol, and they do not perform the same metabolic roles.
9
Q
In which foods is vitamin E found, and why is the intake of polyunsaturated fatty acids related to vitamin E needs?
A
Vitamin E is found in vegetable oils, margarine, salad dressings, and wheat germ oil. Higher intake of polyunsaturated fatty acids requires more vitamin E, and fortunately, they often occur together in the same foods.
10
Q
What are the primary roles of vitamin K in the body?
A
Vitamin K is essential for blood clotting and is involved in the metabolism of bone proteins, including osteocalcin. It may also be associated with a reduced risk of heart disease and some cancers.
11
Q
Under what circumstances may a secondary deficiency of vitamin K occur?
A
A secondary deficiency of vitamin K may occur when fat absorption falters (as in bile production failure) or due to certain drugs disrupting vitamin K synthesis and action.
12
Q
How do vitamin K and vitamin D interact in relation to bone health?
A
Vitamin K helps synthesize a specific bone protein, and vitamin D regulates that synthesis. Both vitamins, along with vitamin A, play important roles in bone growth and remodeling.
13
Q
What is the primary dietary source of vitamin K, and what are the forms of vitamin K found in foods?
A
Leafy green vegetables such as spinach and kale, fruits like avocado and kiwi, and some vegetable oils like soybean oil are primary sources. Phylloquinone and menaquinone are the two forms of vitamin K found in foods.
14
Q
Why is it important for individuals on anticoagulant drugs to monitor their vitamin K intake?
A
High doses of vitamin K can reduce the effectiveness of anticoagulant drugs, so individuals on these drugs should maintain a consistent intake of vitamin K-rich foods and monitor their blood clotting times regularly.
15
Q
What motivates supplement manufacturers to introduce new supplements?
A
he day’s hot topics in nutrition and emerging research news lead supplement manufacturers to develop new supplements. Terms like antioxidants and lycopene become popular, and commercials claim magic in fighting aging and disease.
16
Q
What is a free radical, and how does it become unstable?
A
A free radical is a molecule with one or more unpaired electrons. An electron without a partner makes the molecule unstable and highly reactive. To regain stability, a free radical steals an electron from a stable but vulnerable compound, initiating a chain reaction.
17
Q
How do antioxidants neutralize free radicals, and why don’t they become free radicals themselves?
A
Antioxidants neutralize free radicals by donating one of their own electrons, ending the chain reaction. Antioxidants do not become free radicals because they remain stable in either form.
18
Q
What role do free radicals play in the immune system?
A
Cells of the immune system use free radicals in an “oxidative burst” to demolish disease-causing viruses and bacteria. However, free-radical attacks most often cause widespread damage, contributing to cell damage, disease progression, and aging.
19
Q
What minerals and vitamins act as defense against free-radical damage?
A
Enzymes dependent on selenium, copper, manganese, and zinc, along with antioxidant vitamins (vitamin E, beta-carotene, and vitamin C), defend against free-radical damage.
20
Q
How might antioxidants reduce the risk of cancer?
A
Antioxidants may reduce cancer risks by protecting DNA from free-radical damage. Diets rich in fruits and vegetables, especially those containing vitamin C, beta-carotene, and carotenoids, are associated with lower cancer rates.
21
Q
How does oxidative stress contribute to atherosclerosis, and how can antioxidants protect against heart disease?
A
Oxidative stress contributes to atherosclerosis by oxidizing LDL cholesterol. Antioxidants, especially vitamin E and vitamin C, protect against LDL oxidation, inflammation, and arterial injuries, potentially reducing the risk of heart disease.
22
Q
According to the passage, what dietary strategies are most effective in preventing heart disease?
A
Effective strategies include using unsaturated fats, selecting foods rich in omega-3 fatty acids, and consuming a diet high in fruits, vegetables, nuts, and whole grains while low in refined grain products.
23
Q
Should antioxidants be replenished from foods or supplements, according to the passage?
A
The passage emphasizes that antioxidants are best obtained from foods, especially fruits and vegetables, which offer a range of nutrients and phytochemicals. Taking supplements is not recommended for disease prevention.
24
Q
What does the passage suggest about the use of antioxidant supplements for cancer prevention?
A
The passage suggests that antioxidant supplements may not provide the same benefits as a diet rich in fruits and vegetables. Some studies even indicate potential risks associated with certain supplements, such as increased mortality.
25
What are the main roles of zinc in the body?
Zinc supports the work of proteins in metabolic processes, stabilizes cell membranes and DNA, strengthens antioxidant defenses, assists in immune function, growth, and development. It participates in hormone synthesis, blood clotting, thyroid function, and influences behavior and learning.
26
How does zinc absorption vary with dietary intake?
The rate of zinc absorption varies from 15 to 40 percent. As zinc intake increases, the absorption rate decreases, and as zinc intake decreases, the absorption rate increases. Dietary factors like phytates can influence absorption, limiting bioavailability.
27
What is the enteropancreatic circulation of zinc?
After absorption, zinc circulates between the small intestine and the pancreas. Some zinc reaches the pancreas to be incorporated into digestive enzymes, providing a dual source of zinc for the small intestine. This circulation is known as the enteropancreatic circulation of zinc.
28
What are the symptoms of zinc deficiency?
Zinc deficiency can lead to impaired growth, immature sexual development, digestion issues, diarrhea, compromised immune response, central nervous system damage, poor motor development, cognitive performance, altered taste, loss of appetite, and slowed wound healing.
29
What are the potential side effects of zinc toxicity?
High doses of zinc (more than 50 milligrams) can cause vomiting, diarrhea, headaches, exhaustion, and interfere with copper metabolism, leading to heart muscle degeneration. The UL for adults is set at 40 milligrams.
30
In which foods is zinc most abundant?
Zinc is highest in protein-rich foods such as shellfish (especially oysters), meats, poultry, milk, and cheese. Plant-based diets tend to be low in zinc, but legumes and whole-grain products can be good sources if consumed in large quantities.
31
What essential role does iodine play in the body?
Iodine is integral to thyroid hormones that regulate body temperature, metabolic rate, reproduction, growth, blood cell production, nerve and muscle function. It influences energy expenditure during basal metabolism by controlling cellular oxygen use.
32
What is the primary cause of goiter?
Goiter is primarily caused by iodine deficiency. In iodine deficiency, the thyroid gland enlarges as it attempts to trap more iodine. Some foods containing goitrogens, like collards and kale, can also contribute to goiter by interfering with iodine uptake by the thyroid.
33
How does iodine deficiency impact mental health?
Iodine deficiency is the most common cause of preventable mental impairment. It can lead to poor performance in school, and severe deficiency during pregnancy can result in irreversible mental impairment and stunted physical growth, known as cretinism.
34
What is the UL for iodine intake in adults?
The UL for iodine intake in adults is 1100 micrograms per day. Excessive iodine intake during pregnancy can be especially damaging to the developing infant, potentially causing goiter severe enough to block airways and lead to suffocation.
35
What are the major sources of selenium in the diet?
Selenium is found in soil and crops, with reliable sources being meats, milk, and eggs. Eating as few as two Brazil nuts a day can effectively improve selenium status. Average intakes in the United States exceed the RDA, which is based on maximizing glutathione peroxidase activity.
36
What are the roles of copper in the body?
Copper serves as a constituent of enzymes involved in various metabolic roles, including iron metabolism, collagen manufacturing, inactivation of histamine, degradation of serotonin, and participation in energy metabolism reactions.
37
How can copper deficiency and toxicity occur?
Copper deficiency is rare in typical US diets and is associated with genetic disorders. Excessive copper intake from foods is unlikely, but supplements may cause liver damage. Genetic disorders like Menkes disease and Wilson's disease can lead to copper deficiency or toxicity.
38
What is the role of manganese in the body?
Manganese acts as a cofactor for enzymes facilitating carbohydrate, lipid, and amino acid metabolism. It is essential for bone formation, the conversion of pyruvate to a TCA cycle compound, and maintaining healthy nerves.
39
How does fluoride contribute to oral health?
Fluoride, by forming fluorapatite in teeth, strengthens enamel and makes teeth more resistant to decay. Drinking water, usually the best source of fluoride, helps protect against dental caries. However, excessive fluoride intake can lead to fluorosis, causing tooth damage.
40
How much magnesium is present in a 132-pound person's body?
About 1 ounce of magnesium.
41
Where is more than half of the body's magnesium located?
In the bones.
42
What are the primary roles of magnesium in the body?
Maintaining bone health, forming part of the protein-making machinery, necessary for energy metabolism, participating in hundreds of enzyme systems.
43
What is the major role of magnesium in ATP synthesis?
Acting as a catalyst in the reaction that adds the last phosphate to ATP.
44
What is the dynamic interaction between magnesium and calcium in muscle contraction and blood clotting?
Calcium promotes the processes, while magnesium inhibits them.
45
What are significant dietary sources of magnesium?
Legumes, nuts, seeds, dark green leafy vegetables, and mineral water in areas with hard water.
46
What chronic diseases may be linked to magnesium deficiency?
Heart disease, stroke, hypertension, diabetes, and cancer.
47
How does magnesium contribute to heart health?
It is critical to heart function, protects against hypertension, and supports heart health.
48
What is the bioavailability of magnesium from mineral water, and how can it be improved?
About 50%; it improves when consumed with a meal.
49
What is the rare but potentially fatal side effect of magnesium intake from nonfood sources?
Magnesium toxicity.
50
What is sulfate?
The oxidized form of the mineral sulfur.
51
How is the body's need for sulfate met?
Through a variety of foods, beverages, and sulfur-containing amino acids found in dietary proteins (methionine and cysteine).
52
What is the role of sulfur-containing amino acids in protein molecules?
They help determine the contour of protein molecules by forming disulfide bridges that stabilize the protein structure.
53
Why is there no recommended intake for sulfate?
Because the body's sulfate needs are easily met with normal protein intakes, and deficiencies do not occur with adequate protein consumption.
54
What factors contribute to bone health besides calcium and phosphate?
Adequate protein intake, vitamin D activation, sunlight exposure, hormones (parathyroid hormone, calcitonin, estrogen, testosterone), physical activity, and body weight.
55
How does physical activity support bone growth during adolescence?
Active adolescents have stronger bones in adulthood as muscle strength and bone strength are interconnected.
56
Why is calcium nutrition during the growing years essential?
It is crucial for achieving optimal peak bone mass, and inadequate calcium intake during childhood can lead to suboptimal bone density in adulthood.
57
What are some nutrients, besides calcium, that support bone health?
Adequate protein, vitamin D, vitamin K, vitamin C, magnesium, potassium, vitamin A (in moderation), carotenoids, omega-3 fatty acids.
58
What is a perspective on calcium supplements for bone health?
While foods are generally the best source of nutrients, calcium supplements may be beneficial for those unable to consume enough calcium-rich foods. The choice of supplement type, dose, absorption, and timing should be considered for effectiveness.
59
What are the two compartments of bone?
Cortical bone (outer, hard shell) and trabecular bone (inner, lacy matrix).
60
How do trabecular and cortical bone handle calcium differently?
Trabecular bone readily gives up minerals to the blood when calcium is needed, while cortical bone gives up calcium slowly and steadily.
61
At what age do trabecular bone losses start becoming significant?
In the 30s for both men and women.
62
How does bone loss contribute to osteoporosis?
As bone density declines, bones become fragile, leading to fractures, particularly in the hip.
63
What is the major risk factor for osteoporosis that cannot be changed?
Age.
64
How does gender influence the development of osteoporosis?
Women generally experience greater bone losses than men, especially after menopause.
65
What are some strategies for preventing osteoporosis?
Ensure optimal peak bone mass during childhood and adolescence, maintain a healthy diet and activity habits in early adulthood, avoid smoking and use alcohol moderately, minimize bone loss in later life through nutrition, exercise, and medical consultation.
66
What factors influence the trace mineral contents of foods?
The trace mineral contents of foods depend on soil and water composition, food processing, diet, and the body's bioavailability.
67
Why is assessing trace mineral status challenging?
Assessing trace mineral status is challenging due to the complexity of their roles, difficulty in diagnosing deficiencies, and the potential for mild deficiencies to be overlooked.
68
Explain the importance of avoiding excessive intake of trace minerals.
Most trace minerals can be toxic at intakes only two and a half to eleven times above current recommendations. Exceeding the Upper Level (UL) can lead to adverse effects, and dietary supplements make it easy to surpass recommended intakes.
69
What role do interactions among trace minerals play in the body?
Interactions among trace minerals are common and can be well-coordinated to meet the body’s needs, supporting various physiological functions. However, imbalances or excesses of one mineral can lead to deficiencies or toxicities of others.
70
Why is research on nonessential trace minerals challenging?
Research on nonessential trace minerals like nickel, bromine, vanadium, cobalt, and boron is challenging due to their small quantities in the body and the lack of clear understanding of their functions and deficiencies in humans.
71
What are the two ionic states of iron, and how do they function in the body?
on has two ionic states—ferrous iron (reduced state) and ferric iron (oxidized state). These states allow iron to serve as a cofactor for enzymes involved in oxidation-reduction reactions and as part of electron carriers in the electron transport chain.
72
How does the body regulate iron absorption and maintain balance?
The body regulates iron absorption primarily through ferritin and transferrin. Ferritin captures and stores iron in the cells of the small intestine, releasing it when needed. Transferrin transports iron to various tissues, and the body adapts absorption based on iron stores.
73
What are the dietary factors that enhance or inhibit nonheme iron absorption?
Factors that enhance nonheme iron absorption include vitamin C, MFP factor (found in meat, fish, and poultry), acids, and certain sugars. Inhibitors include phytates, vegetable proteins, calcium, and polyphenols.
74
Why is iron deficiency a significant concern worldwide?
on deficiency is the most common nutrient deficiency globally, affecting over 2 billion people. It can lead to anemia, particularly in preschool children and pregnant women.
75
What are the stages of iron deficiency, and how is it assessed?
Iron deficiency progresses through stages of diminishing iron stores, decreased transport iron, and limited hemoglobin production. Assessment involves measuring serum ferritin, transferrin, transferrin saturation, and erythrocyte protoporphyrin.
76
How does iron deficiency differ from iron-deficiency anemia?
Iron deficiency refers to depleted iron stores, while iron-deficiency anemia is a severe depletion that results in low hemoglobin concentration, leading to symptoms such as fatigue, weakness, and pale skin.
77
Why do premenopausal women often face challenges in meeting their iron needs?
Premenopausal women have higher iron needs but lower energy needs, making it challenging to obtain enough iron from their diets. They may need to consciously choose iron-rich foods at each meal.
78
What are some good sources of iron in the diet?
Meats, fish, poultry, legumes, eggs, fortified grains, and dark greens are good sources of iron. Enriched or fortified foods, especially in the form of bread and cereals, contribute significantly to iron intake.
79
What are the potential health risks associated with iron overload?
Iron overload can lead to toxic accumulation in tissues, causing free-radical damage, infections, cirrhosis, liver cancer, heart failure, and arthritis. Excess iron in the diet or supplements can contribute to iron overload.
80
What factors should be considered when recommending iron supplements?
Iron supplements should be prescribed by a physician after assessing iron deficiency. The dose, formulation, and schedule should be individualized, and supplements should be taken with consideration of potential side effects, such as constipation.
81
What is the role of chromium in the body?
hromium participates in carbohydrate and lipid metabolism.
82
How does chromium help maintain glucose homeostasis?
Chromium enhances the activity of the hormone insulin.
83
What happens when chromium is lacking in the diet?
A diabetes-like condition may develop, characterized by elevated blood glucose, impaired glucose tolerance, insulin response, and glucagon response.
84
Do chromium supplements benefit people with type 2 diabetes?
Research suggests that chromium supplements provide little or no benefit to people with type 2 diabetes.
85
Where is chromium found in the diet?
Chromium is present in a variety of foods, with the best sources being unrefined foods, liver, brewer’s yeast, and whole grains.
86
What is the function of molybdenum in the body?
olybdenum acts as a working part of several metalloenzymes.
87
Are dietary deficiencies of molybdenum common?
No, dietary deficiencies of molybdenum are unknown because the amounts needed are very small.
88
What are molybdenum-rich foods?
Molybdenum-rich foods include legumes, breads, other grain products, leafy green vegetables, milk, and liver.
89
Is molybdenum toxicity common in humans?
Molybdenum toxicity in people is rare and is characterized by kidney damage and reproductive abnormalities.
90
ow do contaminant minerals enter the food supply?
Contaminant minerals like lead, mercury, and cadmium enter the food supply through soil, water, and air pollution.
91
What is the main focus regarding lead in this context?
The section focuses on lead poisoning as it is a serious environmental threat to young children, and reducing blood lead levels is a goal of the Healthy People initiative.
92
How does lead disrupt body processes?
Lead competes with essential minerals like iron and calcium, displacing them from metabolic sites, disrupting body processes, and impairing nutrition status.
93
Why are children with iron deficiency vulnerable to lead toxicity?
Children with iron deficiency are particularly vulnerable to lead toxicity.
94
What is the general impact of contaminant minerals on health?
Contaminant minerals impair the body’s growth, work capacity, and general health.
95
What are phytochemicals, and where are they found?
Phytochemicals are compounds in plant-derived foods with biological activity. They are found in fruits, vegetables, and other plant-based foods.
96
How do phytochemicals defend against chronic diseases?
Phytochemicals may act as antioxidants, mimic hormones, stimulate enzymes, interfere with DNA replication, suppress inflammation, destroy bacteria, and bind to cell walls, preventing chronic diseases.
97
What is the definition of functional foods?
Functional foods include those with potentially beneficial effects on health beyond their nutrient contributions.
98
Give examples of functional foods rich in phytochemicals.
Examples include whole grains, oily fish, fresh fruits, orange juice fortified with calcium, and margarine with plant sterols.
99
What are some examples of phytochemicals defending against specific diseases?
Soy may protect against breast and prostate cancers, while lycopene in tomatoes may offer protection against some cancers.
100
What is the concept of functional foods?
Functional foods naturally contain biologically active phytochemicals and offer health benefits.
101
How do functional foods blur the distinctions between foods and drugs?
Functional foods have characteristics of both foods and drugs, acting like drugs with ingredients that alter body functions.
102
What are some examples of foods acting like drugs?
Margarine enhanced with plant sterols that lower blood cholesterol is an example of a food acting like a drug.
103
What are the challenges in using functional foods as drugs?
Unanswered questions include whether functional foods work, their safety, effectiveness, dosage, and whether they are a healthy choice.
104
What are the potential future developments in the field of functional foods?
Future developments may involve designing specific eating patterns based on individual health needs, merging knowledge of the human genome and nutrition, and creating foods to meet specific health requirements.
105
What motivates supplement manufacturers to introduce new supplements?
The day's hot topics in nutrition and emerging research news lead supplement manufacturers to develop new supplements. Terms like antioxidants and lycopene become popular, and commercials claim magic in fighting aging and disease.
106
What is a free radical, and how does it become unstable?
A free radical is a molecule with one or more unpaired electrons. An electron without a partner makes the molecule unstable and highly reactive. To regain stability, a free radical steals an electron from a stable but vulnerable compound, initiating a chain reaction.
107
How do antioxidants neutralize free radicals, and why don't they become free radicals themselves?
Antioxidants neutralize free radicals by donating one of their own electrons, ending the chain reaction. Antioxidants do not become free radicals because they remain stable in either form.
108
What role do free radicals play in the immune system?
Cells of the immune system use free radicals in an "oxidative burst" to demolish disease-causing viruses and bacteria. However, free-radical attacks most often cause widespread damage, contributing to cell damage, disease progression, and aging.
109
What minerals and vitamins act as defense against free-radical damage?
Enzymes dependent on selenium, copper, manganese, and zinc, along with antioxidant vitamins (vitamin E, beta-carotene, and vitamin C), defend against free-radical damage.
110
How might antioxidants reduce the risk of cancer?
Antioxidants may reduce cancer risks by protecting DNA from free-radical damage. Diets rich in fruits and vegetables, especially those containing vitamin C, beta-carotene, and carotenoids, are associated with lower cancer rates.
111
How does oxidative stress contribute to atherosclerosis, and how can antioxidants protect against heart disease?
Oxidative stress contributes to atherosclerosis by oxidizing LDL cholesterol. Antioxidants, especially vitamin E and vitamin C, protect against LDL oxidation, inflammation, and arterial injuries, potentially reducing the risk of heart disease.
112
According to the passage, what dietary strategies are most effective in preventing heart disease?
Effective strategies include using unsaturated fats, selecting foods rich in omega-3 fatty acids, and consuming a diet high in fruits, vegetables, nuts, and whole grains while low in refined grain products.
113
Should antioxidants be replenished from foods or supplements, according to the passage?
The passage emphasizes that antioxidants are best obtained from foods, especially fruits and vegetables, which offer a range of nutrients and phytochemicals. Taking supplements is not recommended for disease prevention.
114
What does the passage suggest about the use of antioxidant supplements for cancer prevention?
The passage suggests that antioxidant supplements may not provide the same benefits as a diet rich in fruits and vegetables. Some studies even indicate potential risks associated with certain supplements, such as increased mortality.
115
Where are 90 percent of vitamin A stores located in the body?
90 percent of vitamin A stores are located in the liver.
116
What is the role of retinol-binding protein in vitamin A status?
Retinol-binding protein serves as the transport carrier for vitamin A inside the body.
117
How long does it take for deficiency symptoms to appear after vitamin A stores are depleted?
Deficiency symptoms would not begin to appear until after vitamin A stores are depleted, which takes 1 to 2 years for a healthy adult but much sooner for a growing child.
118
Is vitamin A deficiency common in the United States?
Vitamin A deficiency is uncommon in the United States but is a major nutrition problem in many developing countries.
119
How does vitamin A deficiency contribute to unnecessary deaths and blindness?
Vitamin A deficiency is responsible for a million or more unnecessary deaths and cases of blindness each year in developing countries.
120
What are some measures taken to protect against vitamin A deficiencies?
Many countries nourish their people with biofortified corn, rice, and cassava. Routine vitamin A supplementation and food fortification also help prevent deficiencies.
121
What is the relationship between vitamin A and immune function?
Vitamin A supports immune function and inhibits replication of the measles virus.
122
How does vitamin A deficiency contribute to infectious diseases?
The severity of infectious diseases, such as measles, often correlates with the degree of vitamin A deficiency. Providing vitamin A to children diagnosed with measles reduces the risk of dying.
123
What are the early signs of vitamin A deficiency?
Night blindness, the inability to recover promptly from temporary blinding after a flash of bright light at night, is one of the first detectable signs of vitamin A deficiency.
124
What are the consequences of severe vitamin A deficiency?
Severe vitamin A deficiency can lead to total blindness, keratinization of the skin, and weakened defenses against infections.
125
ow does the body synthesize vitamin D?
e body can synthesize vitamin D from a precursor that is made from cholesterol, with the help of sunlight. This means that given enough time in the sun, people do not need vitamin D from foods.
126
What are the two major forms of vitamin D?
The two major forms of vitamin D are vitamin D2 (ergocalciferol), which is derived primarily from plant foods in the diet, and vitamin D3 (cholecalciferol), which is derived from animal foods in the diet or made in the skin from 7-dehydrocholesterol with the help of sunlight.
127
How is vitamin D activated in the body?
Vitamin D, whether made in the body or consumed from the diet, needs to go through two hydroxylation reactions to become fully activated. The liver adds an OH group to produce calcidiol, and then the kidneys add another OH group to produce calcitriol, the active form of vitamin D.
128
What is the role of vitamin D in bone growth?
Vitamin D assists in the absorption of calcium and phosphorus, which helps maintain blood concentrations of these minerals. This, in turn, allows the bones to absorb and deposit these minerals, making them denser and stronger.
129
What are some other roles of vitamin D in the body?
Vitamin D has been found to play a role in cognitive function, muscle growth, immune system function, adipose tissue regulation, and the regulation of genes that control cell growth. It has also been suggested to have potential benefits in protecting against heart disease, type 2 diabetes, inflammation, brain disorders, macular degeneration, hypertension, and some cancers.
130
Does evidence support vitamin D supplementation for overall health?
Currently, evidence does not support vitamin D supplementation for improving health beyond correcting deficiencies.
131
How common is vitamin D insufficiency in the US population?
It is estimated that 16 percent of the US population has low blood levels of vitamin D.
132
hat are the three different forms of vitamin A active in the body?
he three different forms of vitamin A active in the body are retinol, retinal, and retinoic acid.
133
What is the role of retinol in the body?
Retinol supports reproduction and is the major transport and storage form of vitamin A.
134
What is the role of retinal in the body?
Retinal is active in vision and participates in the conversion of retinol to retinoic acid.
135
What is the role of retinoic acid in the body?
Retinoic acid acts like a hormone, regulating cell differentiation, growth, and embryonic development.
136
How does vitamin A participate in vision?
Vitamin A helps maintain a clear outer window of the eye (cornea) and participates in the conversion of light energy into nerve impulses at the retina.
137
What is rhodopsin and how does it relate to vitamin A?
Rhodopsin is a light-sensitive pigment of the retina that contains the retinal form of vitamin A. It plays a central role in vision by responding to light and generating electrical impulses that convey messages to the brain.
138
What happens to retinal when light strikes the retina?
When light strikes the retina, retinal undergoes a cis to trans configuration change, generating an electrical impulse that conveys the message to the brain.
139
How is rhodopsin regenerated?
Much of the retinal is converted back to its active cis form and combined with the opsin protein to regenerate rhodopsin.
140
What are the major roles of vitamin A in the body?
The major roles of vitamin A include promoting vision, participating in protein synthesis and cell differentiation, and supporting reproduction and regulating growth.
141
How does the body obtain vitamin A from foods?
The body obtains vitamin A from foods that contain retinoids (animal-derived) or carotenoids (plant-derived), which can be converted to vitamin A.
142
How does activity contribute to energy expenditure indirectly?
Activity contributes to energy expenditure indirectly by speeding up metabolism for hours or even days after exercise, raising the energy expenditure of exercise up to 15 percent.
143
What is the long-term impact of daily vigorous activity on body composition?
Engaging in daily vigorous activity over the long term leads to the development of more lean tissue, resulting in a rise in metabolic rate that supports continued weight loss or maintenance.
144
Explain how physical activity affects body composition, especially in terms of body fat.
Physically active individuals have less body fat than sedentary people, leading to a change in body composition—decreasing body fat and increasing lean body mass.
145
Contrast the impact of activity on appetite in sedentary people versus active individuals.
Research does not support the idea that exercise causes overeating in active individuals; in fact, sedentary people participating in ongoing activity programs tend to reduce their energy intake.
146
Explain why hard physical work and eating are considered incompatible.
The body releases fuels from storage to support exercise, making it necessary to calm down and put energy fuels back in storage before eating.
147
How can exercise help in curbing inappropriate appetite related to boredom, anxiety, or depression?
Exercise may help curb inappropriate appetite by providing an alternative to eating when not hungry, passing time, relieving anxiety, and preventing inappropriate eating.
148
What are the psychological benefits of regular physical activity?
Regular physical activity helps reduce stress, improves body image, and separates the connections between body weight and self-worth.
149
What factors should individuals consider when choosing physical activities for a weight-management program?
Individuals should choose activities they enjoy and are willing to do regularly; any physical activity is better than being sedentary.
150
What advice do health-care professionals frequently give regarding physical activity for weight management?
Health-care professionals often advise engaging in activities of low-to-moderate intensity for a long duration, such as an hour-long, fast-paced walk.
151
Explain the concept of "spot reducing" and how exercise can help with trouble spots.
Spot reducing is a misconception; exercise can help with trouble spots by releasing fat stores during aerobic exercise, but specific exercises do not target fat loss in particular areas.
152
What are the cognitive skills important for successful behavior change in weight management?
Successful behavior change depends on problem-solving and cognitive restructuring, involving identifying problems, generating solutions, and replacing negative thoughts with positive ones.
153
Why is group support considered helpful in making lifestyle changes?
Group support provides a structured environment for individuals making lifestyle changes, offering motivation, shared experiences, and guidance.
154
What role does physical activity play in preventing weight gains and maintaining weight losses?
Physical activity plays a key role in preventing weight gains and maintaining weight losses, with consistent exercise being more successful than inactivity.
155
What are the strategies recommended by the National Weight Control Registry for maintaining weight loss?
The National Weight Control Registry recommends strategies such as eating a low-kcalorie diet, engaging in regular physical activity, monitoring weight frequently, and seeking support from healthcare professionals or groups.
156
What are the key strategies for preventing weight gain, according to the chapter?
Key strategies for preventing weight gain include eating regular meals, selecting sensible portion sizes, being physically active, and limiting sedentary activities.
157
How does the chapter recommend addressing underweight through diet-planning strategies?
Adequacy and balance are key diet-planning strategies for weight gain, involving energy-dense foods, regular meals, large portions, extra snacks, and strength training.
158
What criticisms are mentioned about fad diets in the chapter?
Fad diets are criticized for not offering a safe and effective long-term plan for weight loss, often making outrageous claims without credible research.
159
What advice does the chapter provide for individuals seeking information on popular diets?
The chapter suggests being cautious when considering popular diets, emphasizing the importance of sound scientific research and recommending evaluations by the Academy of Nutrition and Dietetics as a resource.
160
escribe the functions of magnesium in the body and identify food sources rich in magnesium.
Magnesium is involved in over 300 enzymatic reactions, including energy metabolism, muscle function, and bone health. Foods rich in magnesium include green leafy vegetables, nuts, seeds, whole grains, and legumes.
161
What is the role of sulfur in the body, and which foods are good sources of sulfur?
Answer: Sulfur is a component of thiamin and biotin, amino acids, and vitamins. It is found in protein-containing foods such as meats, fish, poultry, eggs, milk, and legumes.
162
Define heme iron and non-heme iron, and explain their sources and absorption rates.
Answer: Heme iron is found in animal-based foods and has higher bioavailability. Non-heme iron is present in plant-based and animal-based foods, with lower bioavailability. Absorption of non-heme iron is influenced by factors like vitamin C, acids, and certain compounds.
163
What is the significance of iron in the body, and what are the consequences of iron deficiency and iron toxicity?
Answer: Iron is crucial for oxygen transport, energy metabolism, and immune function. Iron deficiency can lead to anemia, fatigue, and impaired cognitive function. Iron toxicity can cause organ damage and other health issues.
164
Explain the role of zinc in the body, its functions, and food sources.
Answer: Zinc is involved in DNA synthesis, immune function, wound healing, and taste perception. Food sources of zinc include meat, poultry, fish, dairy products, and whole grains.
165
Describe the functions of copper in the body and identify dietary sources of copper.
Answer: Copper is involved in iron metabolism, connective tissue formation, and antioxidant defense. Dietary sources of copper include organ meats, seafood, nuts, seeds, and whole grains.
166
What are the functions of selenium, and which foods are good sources of selenium?
Answer: Selenium is essential for antioxidant defense, thyroid hormone metabolism, and immune function. Good sources of selenium include Brazil nuts, seafood, meat, poultry, and whole grains.
167
Define iodine and its role in the body, highlighting dietary sources.
Answer: Iodine is crucial for thyroid hormone synthesis, which regulates metabolism. Dietary sources of iodine include iodized salt, seafood, dairy products, and some vegetables.
168
What are the functions of fluoride in the body, and how is it related to dental health?
Answer: Fluoride is essential for dental health, promoting tooth enamel strength and preventing dental caries. It works by remineralizing and strengthening tooth enamel.
169
Explain the role of chromium in the body, its functions, and sources of chromium in the diet.
Answer: Chromium enhances insulin action, contributing to glucose metabolism. Food sources of chromium include meats, whole grains, and some fruits and vegetables.
170
What percentage of an adult's body weight is water?
About 60 percent.
171
How does body composition influence the proportion of water in the body?
Water makes up about 75 percent of the weight of lean tissue and less than 25 percent of the weight of fat. The proportion of water is generally smaller in females, obese people, and the elderly due to their smaller proportion of lean tissue.
172
List some functions of water in the body fluids
Carries nutrients and waste products throughout the body, maintains the structure of large molecules such as proteins and glycogen, participates in metabolic reactions, serves as a solvent for minerals, vitamins, amino acids, glucose, and other small molecules, acts as a lubricant and cushion around joints and inside the eyes.
173
What are the benefits of fitness?
The benefits of fitness include restful sleep, improved body composition, strong bones, better resistance to illness, lower risk of some cancers, improved circulation and lung function, lower risk of cardiovascular disease, reduced risk of type 2 diabetes, lower risk of gallbladder disease, lower risk of anxiety and depression, stronger self-image, longer lifespan, and improved quality of life.
174
What are the health risks associated with physical inactivity?
Physical inactivity is linked to major chronic diseases such as heart disease, cancer, stroke, diabetes, and hypertension. It can also lead to obesity, poor sleep quality, and weakened immune system.
175
How does physical activity improve body composition?
Physical activity helps to build muscle and burn fat, resulting in a lower body fat percentage and a healthier body composition.
176
How does physical activity improve bone density?
Weight-bearing physical activity, such as walking, running, and jumping, stimulates bone cells and promotes bone density, which can help to prevent osteoporosis.
177
How does physical activity reduce the risk of some cancers?
Physical activity has been shown to reduce the risk of colon cancer, breast cancer, and some other types of cancer. The exact mechanisms are not fully understood, but it is believed that physical activity may help to regulate hormones, reduce inflammation, and boost the immune system.
178
How does physical activity improve cardiovascular health?
Physical activity strengthens the heart and lungs, lowers blood pressure, and improves blood cholesterol levels, all of which contribute to a lower risk of cardiovascular disease.
179
How does physical activity reduce the risk of type 2 diabetes?
Regular physical activity helps to improve insulin sensitivity and reduce blood sugar levels, which can help to prevent or manage type 2 diabetes.
180
How does physical activity reduce the risk of gallbladder disease?
Physical activity helps to reduce the risk of gallbladder disease by promoting weight loss and lowering blood lipid levels.
181
How does physical activity improve mental health?
Physical activity has been shown to improve mood and reduce symptoms of depression and anxiety. It is believed that exercise may help to release endorphins, which have mood-boosting effects.
182
How does physical activity improve self-image?
Physical activity can help to boost self-confidence and self-esteem by providing a sense of accomplishment and achievement.
183
How does physical activity increase longevity?
Physical activity has been shown to extend lifespan and improve quality of life in later years. Even a small amount of activity can make a difference.
184
What are myokines and how do they influence health?
Myokines are proteins released by skeletal muscles during physical activity. They signal changes in skeletal muscle as well as in adipose tissue and organs such as the liver. Myokines are thought to play a role in regulating energy balance, insulin sensitivity, inflammation, and other body functions.
185
What are the minimum recommended levels of physical activity for most adults?
Most adults should engage in at least 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous-intensity aerobic activity each week. The activity should be spread throughout the week, ideally on most of the days.
186
What are the benefits of exceeding the minimum recommended levels of physical activity?
Exceeding the minimum recommended levels of physical activity can provide even greater health benefits, such as a lower risk of premature death, improved cardiorespiratory fitness, and a healthier body composition.
187
What are the ACSM guidelines for physical activity?
The ACSM guidelines for physical activity recommend that adults engage in at least 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous-intensity aerobic activity each week. They also recommend strength training exercises that work all major muscle groups at least two days per week.
188
What are the benefits of following the ACSM guidelines for physical activity?
Following the ACSM guidelines for physical activity can help to improve cardiorespiratory endurance, body composition, strength, and flexibility. It can also reduce the risk of chronic diseases and improve overall health and well-being.
189
Why is it important to maintain an active lifestyle every day?
It is important to maintain an active lifestyle every day in order to reap the full benefits of physical activity and maintain good health. Regular physical activity helps to keep the body strong, healthy, and functioning at its best.
190
What are the two phases of muscle protein turnover?
uscles are constantly breaking down and rebuilding protein. The breakdown phase is called degradation, and the rebuilding phase is called synthesis.
191
What is the difference between hypertrophy and atrophy?
Hypertrophy vs. atrophy: Hypertrophy is an increase in muscle mass, while atrophy is a decrease in muscle mass.
192
How do muscles adapt to different types of physical activity?
Muscle adaptation: Muscles adapt to the demands of physical activity by building new proteins and structures. Muscles used for strength training will develop more mass, while muscles used for endurance training will develop more endurance.
193
What are some strategies for building fitness and preventing injuries?
Building fitness and preventing injuries: Strategies include engaging in a variety of activities, using proper equipment and form, warming up and cooling down, training progressively, listening to your body, and starting slowly.
194
What are some cautions to consider before starting a fitness program?
Cautions before starting a fitness program: People with certain risk factors may need medical clearance before starting a fitness program. It's important to start slowly and gradually increase intensity.
195
What are the five components of fitness?
Flexibility, muscle strength and endurance, cardiorespiratory endurance, and body composition.
196
How does flexibility contribute to fitness?
Flexibility: Allows joints to move freely, reducing risk of injury.
197
Why is cardiorespiratory endurance important?
Cardiorespiratory endurance: Supports sustained activity through efficient oxygen delivery.
198
What are the benefits of cardiorespiratory conditioning?
Benefits of cardiorespiratory conditioning: Increased cardiac output, slower resting pulse, improved circulation, and lower blood pressure.
199
What are the key components of muscle strength and endurance training?
Muscle strength and endurance training: Builds muscle mass, strength, power, and endurance.
200
Why is it important to personalize your fitness program?
Individual needs and goals vary, so programs should be tailored accordingly.
201
What are some factors to consider when choosing physical activities?
Choosing activities: Consider enjoyment, fitness goals, and physical limitations.
202
How do aerobic activity, stretching, and resistance training contribute to a balanced fitness program?
Balanced program: Combines aerobic activity, stretching, and resistance training.
203
What are some examples of balanced fitness programs?
Program examples: Walking, cycling, swimming, yoga, weightlifting, Pilates.
204
What nutrients are essential for supporting physical activity?
Carbohydrates, fats, proteins, vitamins, minerals, and water.
205
How do carbohydrates, fats, and proteins contribute to energy production and tissue building?
Carbohydrates and fats: Provide fuel for energy production.
206
Why are vitamins and minerals important for physical activity?
Proteins: Build and repair muscle tissue.
207
What is the role of water in physical activity?
Vitamins and minerals: Support energy metabolism and tissue building.
208
How can you ensure that your diet provides the nutrients you need for optimal fitness?
Ensuring optimal nutrition: Eat a balanced diet rich in fruits, vegetables, whole grains, lean protein, and healthy fats.
