Nutrition 251 Exam #3
Terms in this set (212)
The bomb calorimeter overestimates what?
The actual amount of energy available in food for human body.
Sarah and Sonja both consumed approximately 2000 kcalories per day. What could you conclude about Sarah and Sonja's energy balance based upon this information?
You cannot draw any conclusions based on this information.
The feeling of satisfaction between meals is termed...
Among the following, which would be most satiating during a meal?
The thermic effect of foods is highest for which of the following?
100 kcalories of tuna.
Which of the following should Sam do, if he wanted to increase the amount of energy he expended as part of his basal metabolism?
Start a workout program to build lean body mass.
Sally is a typical college student. What fraction of her daily energy expenditure is represented by her basal metabolism?
The health risks and physiological limitations for being an underweight woman (as defined by the CDC) includes:
difficulty keeping warm, decreased ability to conceive a child and increased risk for osteoporosis.
Laura has calculated that her BMI is 22. She would be considered...
Theoretically, how many kcalories do you have to remove from your diet (and/or expend extra through more exercise) EACH DAY to lose one pound of body fat in one week?
Which of the following is a feature of the lipoprotein lipase (LPL) enzyme?
Its activity in men and women are sex-related and explain the differences in major fat storage regions of the body.
Which of the following statements is TRUE about hormones that regulate food intake?
Elevated gherlin triggers the desire to eat.
Set Point Theory:
explains why it is so difficult for overweight people to lose weight and keep it off and is the sum total of physiological control of weight status.
According to body mass index (BMI) values and CDC cutoff definitions, about what percent of the U.S. adult population is considered overweight or obese (ie. combined)?
When a diet leads to a quick weight loss (5-10 lb in one week), the weight primary comes from which part of the body?
The Weight Maintenance Wheel from your lesson, contains all the following components:
Behavior modification techniques, a healthy eating plan
and regular physical activity.
For a healthy eating plan for weight loss, Chapter 9 advises "watch for other empty kcalories." What are these "other kcalories?"
A weakness of the Wheat Belly diet is that it...
is too restrictive and may limit B vitamins, calcium and vitamin D.
According to the Nova video on Obesity, the MC4 receptor is...
mutated in Theresa and thus does not signal her to stop eating.
Another term for vitamin B6 is:
Which best describes a coenzyme?
small, organic molecule
General characteristics of most of the water-soluble vitamins include all of the following EXCEPT...
they must be consumed with each meal.
Which of the following would provide the most riboflavin in the typical American diet?
T/F: Since manufacturers started fortifying milled grain products with folate, the rate of scurvy have declined substantially.
Which of the following vitamins are found in foods across most food groups and thus deficiency is extremely rare?
vitamin B6 and pantothenic acid
John is looking to increase his dietary sources of vitamin C. However, he expresses a strong dislike for all citrus fruits. Which of the following shopping lists would you recommend?
Brussels sprouts, broccoli, strawberries
Which of the following vitamins is involved substantially in energy metabolism, that is, ATP production?
One of the water-soluble vitamins has been in many claims in magazines that it will improve a brain neurotransmitter, and thus may help such conditions as premenstrual syndrome (PMS). Unfortunately, double-blind controlled studies do not confirm these claims. This vitamin is
functions in a coenzyme to carry hydrogens and their electrons to the electron transport chain.
Scurvy results in pinpoint hemorrhaging in the skin and bleeding of the gums. This can be explained by the biological function of ______ to keep the mineral _____ in the correct form so that it acts as a cofactor for the enzyme necessary for _______ synthesis.
ascorbic acid; iron; collagen
Which of the following is the coenzyme form of thiamin?
A general niacin deficiency is known to be manifested in abnormalities of all of the following organs/systems EXCEPT what?
Which of the following diets is most likely to lead to beriberi, a deficiency seen in poor countries, but rarely in the U.S.?
High intakes of white, refined rice
You are a dietitian and see the report of the blood work from a woman in her twenties who is pregnant. Her red blood cells are larger than normal, so you suspect that her diet is low in
The appearance of the neurological symptoms of pernicious anemia may be delayed due to high intake of supplements of...
A deficiency of which vitamin(s) can result in accumulation of homocysteine in the blood?
vitamin B6 and folate.
Which of the following is a side effect of large amounts of vitamin C supplementation?
giving false positive diabetes tests, giving false negative diabetes test, and acting as a prooxidant in the body.
The UL for vitamin C is ______ , whereas, the amount you might be eating everyday is _______ .
2,000 mg/day; 100 mg/day.
Fred just consumed a tuna sandwich and a glass of milk which contains 180 mg of tryptophan. Fred has the capacity to make ____ mg of _______ from this meal.
3 mg; niacin.
What is the major carrier of the fat-soluble vitamins from the intestinal epithelial cell to the circulation?
Which of the following is not a fat-soluble vitamin?
Which of the following food substances can be converted to vitamin A in the body?
Which of the following provides the LEAST amount of precursor vitamin A?
Which of the following describes an association of vitamin A and vision?
Light causes retinal to shift from a cis to a trans configuration.
Which of the following describes an event in the visual response process?
Light energy strikes the retina and excites pigments to release retinal.
results in permanent blindness because of damage to the cornea.
It is July and we've been having sunny weather in State College. You are watching your friend's soccer matches wearing a short sleeve shirt and light weight long pants. You tend to go watch 2-3 times per week. How long will it take a fair skinned individual to meet his/her vitamin D needs?
5-10 minutes for each match.
In what tissue(s) must a molecule of vitamin D be chemically altered to yield a compound that is fully active?
Liver and kidney.
What happens regarding the active, hormone form of vitamin D when blood calcium is low?
It acts on the kidney to decrease the urinary excretion of calcium; It acts on small intestinal cells to increase absorption of calcium; and It acts on bone to increase mobilization of calcium out of bone and into blood.
Why are elders at risk for marginal vitamin D deficiency?
With aging, adults decrease their abilities to convert vitamin D to the hormone form and elders typically drink little milk.
Which of the following is NOT a good source of vitamin E in the American diet?
How is vitamin E thought to play a role in reducing the risk of heart disease?
It slows oxidation of low-density lipoproteins.
T/F: A recent clinical trial found that smokers who were given supplements of beta-carotene had increased risk for lung cancer compared to those not given beta-carotene.
All of the following compounds found in food are part of the antioxidant defense system:
beta-carotene, lutein and isoflavones.
Of the following, which would most readily induce a vitamin K deficiency?
Orally taken antibiotic therapy.
Vitamin K is:
Your sister Ellen has just joined the Peace Corps and will be working on ways to improve the nutritional status of children in Indonesia. Once there, she saw that many of the children and some adults suffer from night blindness. Which of the following foods should she recommend be incorporated into the Indonesian diet to help prevent future generations from developing this condition?
Your old friend from high school has just moved to Northern Canada to do full-time research on bats in caves. She typically works in the caves during the day when the bats are there and leaves at sundown when the bats are active. Since your friend only purchases organic and all natural foods, which of the following would you most likely advise she buy regularly at the grocery store?
Vitamin D-fortified milk.
Studies in developing countries have demonstrated that the mortality rate of children with measles can be significantly reduced by providing supplements of:
Tony is on vacation so over the last 2 weeks he drank 2 beers (equal to 240 kcals) every day in addition to the kcals necessary to maintain body weight. Using the 3500 kcal rule, how much weight would he theoretically gain in these two weeks? Hint: How many Calories (kcals) are equivalent to one pound of adipose tissue (fat tissue)? (Lesson 7A and Chpt 8) Indicate to Tony what the limitations of this estimate are.
3500kcals are equivalent to one pound of adipose tissue. 240 X 14 = 3,360. Tony would gain almost a pound.
What does a bomb calorimeter measure? Briefly describe how it works.
A bomb calorimeter is an instrument that measures the heat energy released from foods when burned, thus providing an estimate of potential energy of the foods. When food is burned, the energy in the chemical bonds is released as heat. The heat is then captured in the water that is in the calorimeter and changes the temperature of the water, which is then measured to estimate the amount of potential energy.
The heat generated in a bomb calorimeter for protein is 5.6 kcal/g, yet on a food label it tells me that protein is 4 kcal/gram. Why are these values different?
Because the human body is not as efficient as a bomb calorimeter. Therefore, the potential energy from the calorimeter is multipled by a digestibility coefficient that takes into account that not all nutrients are digested and absorbed. Also, the body can't use nitrogen bonds for energy, so a nitrogen factor is subtracted from the potential energy as well.
List the physiological fuel values for carbohydrate, protein, fat, and alcohol?
Carbohydrate: 4 kcal/g; Protein: 4 kcal/g; Fat: 9 kcal/g; Alcohol: 7 kcal/g
Hunger signals a physiological need for food.
You stop eating after a meal because of satiation due to signals from your stomach and hormone changes.
refers to the time between meals. This is the continued feeling of fullness and satisfaction that inhibits your eating until the next meal.
For humans, appetite influences the amount of food you consume and is affected by a multitude of factors (i.e., sight or aroma of food, emotions, routines, stress, illness, unfamiliarity of food). Appetite is independent of true physiological signals of hunger and fullness.
What nutrient is considered most satiating?
Protein. High fiber foods are satiating because they fill the stomach and slow absorption.
Define low energy density.
Low energy density = feel more full for longer.
Explain the difference between dietary fat having a low satiation in the stomach, verses fat producing satiety signals when in the small intestine.
Fat in a meal results in little satiation because of its high energy density. However, cholecystokinin is released from the small intestine when fat is present. This chemical sends a strong signal of satiety and inhibits food intake.
Describe indirect calorimetry in measuring energy expenditure in humans.
Indirect calorimetry measures energy expenditure in humans by measuring the amount of oxygen that the body consumes.
You expend energy (ie. uses food for fuel) in three categories. List these categories and define them. For the average semi-sedentary American, what category is responsible for the most calorie expenditure?
Basal Metabolic Rate - the energy required to maintain life when the body is at complete rest and fasting for 12 hours. Thermic Effect of Food - the energy to process food through digestion and absorption. Physical Activity - the energy of voluntary movements of skeletal muscle. Basal metabolic rate is responsible for the most caloric expenditure.
If Sonia ate the same amount of kcalories from her flounder, her olive oil, and her rice, which would have the highest thermic effect of food?
Her flounder would have the highest thermic effect because it takes more energy to process protein than carbohydrates. Rice would the second highest thermic effect because it take more energy to process carbohydrate than fat, so olive oil would have the least thermic effect.
What factors or characteristics can raise basal metabolic rate?
Factors that can raise BMR: Body Composition - leaner means higher BMR; Gender - males have higher BMR from male hormones; Fever; Environmental Temperature - both hot and cold raise BMR; Hormones; Smoking.
What factors can lower basal metabolic rate?
Factors that can lower BMR: Body Composition - heavier means lower BMR; Gender - females have lower BMR from female hormones; Age - BMR drops as we get older; Fasting/starvation or a lower calorie diet; Hormones.
When you eat a very low kcal intake from your usual kcal intake for a few days, what happens to your BMR?
Your BMR will drop if you eat a lower calorie diet.
What variables are accounted for in the DRI equation for calculating Total Energy Expenditure?
Gender, height, weight, age and physical activity.
What variable that could contribute to a teenager's Total Energy Expenditure (TEE), is not accounted for in the TEE for adults?
Would they be considered underweight, healthy weight, overweight or obese? List these cutoffs.
Underweight - below 18.5; Healthy Weight - 18.5 to 24.9; Overweight - 25 to 29.9; Obese - greater than or equal to 30.
What are two other criteria (besides BMI) which should be used to determine healthy body status in an individual?
The two other criteria are: Be "metabolically fit" - lack biochemical risk factors for chronic illness and have a body fat distribution that minimizes risk for disease.
Why is BMI not a perfect indicator of health risks?
It only takes height and weight measurements into account, not body composition. Because of this, a person composed of mainly muscle could be classified as overweight without actually being so.
Some people need more body fat; explain.
Some people need more body fat due to outside factors that would affect it like environmental factors or pregnancy.
Is your body an apple or a pear? So what; why is this important? What are the cut-offs in terms of adult waist circumferences and risk for increased chronic diseases?
Pear. It tells where your extra body fat will be deposited on your body. Apple body will deposit most of their fat across their waistline and pear body will deposit their fat below their waistline. Depositing fat along your waistline is more unhealthy that below your waist. In women, a waist circumference greater than 35 and in men, a waist circumference greater than 40 inches have high risk chronic diseases associated with obesity.
True or false and explain? There are no health risks associated with being underweight (BMI<18.5), especially in women.
FALSE; An underweight person can have a harder time preserving lean tissue during a fight against a wasting disease such as cancer. Underweight women can develop menstrual irregularities and become infertile.
As defined by the Center for Disease Control (CDC), what is the approximate prevalence of adult overweight plus obesity combined for US adults? What is the prevalence of obesity alone?
68% of all US adults are either overweight or obese; 34% is prevalence of obesity in US adults alone.
Sonia has struggled with overweight throughout her childhood and adult life. Zoom ahead 20 years and Sarah becomes obese in her 40's. Explain the differences between fat cell development between Sonia and Sarah. Explain why Sonia will likely have more difficulty losing weight than Sarah will.
Differences- once you consume fat, it is stored in adipose cells which can swell or divide, increasing the number cells to accommodate energy storage. When we try to lose weight, fat cells shrink in size but number of fat cells stays the same.
Fat cells are large in number and in size.
Fat cells are normal in number, large in size.
Where is LPL located in the body?
LPL is located on the surface of cells that line blood vessels.
What are the differences in LPL distribution between females and males?
In women, there are fat cells in the breasts, hips, and thighs produce abundant LPL. In men, fat cells in the abdomen produce abundant LPL.
What are the differences in LPL distribution between lean and obese humans?
Obese people generally have more LPL activity in their adipose cells than lean people which make it easier.
Describe the Set-Point Theory. Does this mean that no one can ever lose weight and keep it off?
The Set-Point Theory is that the human body always tends towards homeostasis, or physiological balance. When weight decreases, basal metabolism decreases as well making weight loss harder. When body weight increases, basal metabolism increases making weight gain harder. This does NOT mean that no one can ever lose the weight and keep it off. Exercise combined with a healthy diet can help alter or maintain the body's weight even though the body wants to move towards homeostasis.
What is the misconception in this student quote? "The less dietary fat I take in, the less body fat I will have."
No matter what you take in, if you exceed your allotted amount of calories for the day, then you will gain weight.
Many health experts describe our environment here in the U.S. as "obesogenic." Why?
One that includes all of the factors surrounding a person that promote weight gain, increased food intake, especially of unhealthy choices, and decreased physical activity. Support of this lifestyle is prevalent in the US.
They have heard about leptin, neuropeptide Y, and cholecystokinin (CCK). From a purely speculative point of view, which of these might help each to either reduce or increase their appetite and food intake, as wished?
Weight Loss: Leptin, CCK; Weight Gain: Neuropeptide Y
the "satiety hormone", is a hormone made by fat cells which regulates the amount of fat stored in the body. It does this by adjusting both the sensation of hunger, and adjusting energy expenditures.
In the brain, it is produced in various locations including the hypothalamus, and is thought to have several functions, including: increasing food intake and storage of energy as fat, reducing anxiety and stress, reducing pain perception, affecting the circadian rhythm, reducing voluntary alcohol intake, lowering blood pressure, and controlling epileptic seizures.
hormone improves digestion by slowing down the emptying of food from the stomach and stimulating the production of bile in the liver as well as its release from the gall bladder. Increases the sensation of fullness in the short term.
What weight would health experts set as a safe and reasonable goal for Sonia to attain from a weight loss diet? (In Chapter 9, it gives the recommendation that Sonia should lose about ___ % of her body weight over a 6 month period or ____ lbs/week. See pg. 277)
Sonia should lose about 5 to 10 percent of her body weight over a six month period or ½ to 2 pounds a week.
How many kcals do you have to remove from your diet (and/or expend by exercise) to lose about 1 pound of body weight per week? (This is a refresher from lesson 7A.) Describe the limitations of this calculation (Lesson 7A). Most probably, does this calculation overestimate or underestimate actual weight loss projections in humans?
You need to remove 500 kcals. It overestimates the actual weight loss projections in humans.
Weight Maintenance Wheel:
comprehensive approach for healthy weight including behavior modification, physical activity and a healthy eating plan.
Now list factors identified as important when developing eating plans for weight loss and maintenance of a healthy weight.
Emphasize nutritional adequacy; Eat small portions; Slow down; Lower energy density; Remember water; Focus on fiber; Choose fats sensibly; Select carbohydrates carefully; Watch for other empty kcals.
Experts recommend that weight reduction diets should not be below 1200 kcal per day. Why?
it is impossible to eat the MyPlate recommendations; it is difficult or impossible to get all your vitamin and mineral needs without a supplement; often a person experiences headaches and weakness on such calorie deprivation; it is very difficult to sustain resulting in abandoning the diet or succumbing to the urge to binge.
List and review the components of behavior modification strategies that can be used to assist in sustained behavior change in order to lose weight or maintain a healthy body weight.
Become aware of behaviors; Change behaviors; Cognitive skills; Personal attitudes; Support groups.
What is the recent recommendation for physical activity for weight maintenance or weight loss? (Use the recommendation on p. 281: ____ minutes of moderately intense physical activity/day in addition to activity of daily life.)
200 to 300 minutes of moderately intense physical activity/week in addition to activity of daily life.
List the benefits of physical activity for managing body weight.
increases lean body mass; increases basal metabolic rate; improves cardiovascular fitness, decreases blood pressure, and decreases insulin resistance; increases feelings of well being and self esteem.
surgeon constructs a small stomach pouch and creates an outlet directly to the small intestine, bypassing most of the stomach, the entire duodenum, and some of the jejunum.
the surgeon uses a gastric band to create a small stomach pouch. The size of the opening can be adjusted by inflating or deflating the band by way of a port placed in the abdomen just beneath the skin.
List the 4 criteria for approving an adult for gastric bypass surgery.
Unable to achieve adequate weight loss with diet and exercise; BMI greater than 40 or equal to 35 with weight-related problems (diabetes or hypertension); no medical or psychological contradictions; understanding of risks and strong motivation to comply with post-surgery treatment plan.
List some possible complications due to this procedure.
vitamin and mineral deficiencies, weight gain may re-occur, and psychological problems may happen.
The success of long term effectiveness of gastric surgery depends on ____________________.
compliance with dietary instructions.
The author strongly suggest, "Don't count _____," and "The goal in not simply weight loss, but health ____."
strengths - encourages daily exercise, moderate salt intake and lifelong weight management; weaknesses - restricts carbohydrates to induce ketosis which can cause nausea, light-headedness, and fatigue and can worsen medical problems such as kidney disease; not suited for vegetarians and others who prefer not to emphasize animal proteins.
Wheat Belly Diet:
strengths - creates a low-kcalorie diet; weaknesses - restrictive diet would likely be low in B vitamins, calcium and Vitamin D.
Zen Diet Revolution:
strengths - offers a basic nutrition approach that does no harm; reminds you to make food meaningful and treat your body with respect; weaknesses - recommendations to use fat-burning herbs, supplements, and green tea to decrease fat cells are unsubstantiated and expensive.
Many health professionals believe that since weight reduction diets are very unsuccessful in terms of long term weight maintenance, that the most positive public health mission is to promote the "Non-Diet Approach." This is especially important for children and adolescents in terms of doing no harm (ie, body image and self esteem issues). Describe the principles of the non-diet philosophy.
Human beings come in a variety of sizes and shapes. Diversity is a positive characteristic of the human race; There is no ideal body size, shape, or weight that every individual should strive to achieve; Self-esteem and body image are strongly linked. Helping people feel good about their bodies can help motivate them to maintain healthy behaviors; Appearance stereotyping is inherently unfair and based on superficial factors over which the individual has little or no control; We respect the bodies of others even though they might be quite different from our own; Each person is responsible for taking care of his or her body; Good health is not defined by body size; it is a state of physical, mental, and social well-being; People of all sizes and shapes can reduce their risk of poor health by adopting a healthy lifestyle.
catalyst to speed up processes, hundreds of reactions taking place in a cell.
organic molecule made of carbon, works with enzyme to perform its catalytic job.
category of organic nutrients needed in small amounts but are essential for life.
biological molecule that the enzyme will work on.
what you get from an enzymatic reaction.
Flavin adenine dinucleotide and flavin mononucleotide
Nicotinamide adenine dinucleotide and NADP
Describe the common characteristics of all vitamins.
Vitamins are individual units; they are not linked together. Vitamins do not yield energy when metabolized; many of them do, however, assist the enzymes that participate in the release of energy from carbohydrates, fats and proteins. The amounts of vitamins people ingest from foods and the amounts they require daily are measured in micrograms or milligrams rather than grams.
B Vitamins and Vitamin C: Absorbed directly into the blood; travel freely; circulate freely in water-filled parts of the body; kidneys detect and remove excess urine; possible to reach toxic levels when consumed from supplements; needed in frequent doses (perhaps 1 to 3 days).
Vitamins A, D, E, K: Absorbed first into the lymph, then the blood; many require transport proteins, stored in the cells associated with fat; less readily excreted; likely to reach toxic levels when consumed from supplements, need in periodic doses (perhaps weeks or even months).
Are vitamins all organic molecules?
Vitamins Found Across Many Food Groups:
Pantothenic Acid, Vitamin B6
Handful of Peanuts:
Folate, Niacin as Tryptophan
Scoop of Pretzels:
Folate, Riboflavin, Niacin, Thiamin
Niacin, Thiamin, Riboflavin, Folate
Niacin as Tryptophan, Vitamin B12
Vitamin C, Folate
Glass of 1% Milk:
Riboflavin, Vitamin B12, Niacin as Tryptophan
Why is beriberi a potential problem in populations which consume most of their kcals from "polished" rice?
Rice provided 80% of the energy intake of the people in that area and the germ and bran of their rice grain was their principal source of thiamin. When the germ and bran were removed in the preparation of white rice, beriberi became rampant.
Americans eat lots of polished rice, yet do not get beriberi, why?
Refined grain products such as breakfast cereals, white flour (bread, pasta, etc.), and rice in the United States are fortified with thiamin.
What American subpopulation may be at risk for thiamin deficiency and why?
Malnourished and homeless people are at risk for deficiency as well as people who derive most of their energy from empty-kcalorie foods and beverages.
Briefly describe the metabolic role of thiamin.
Thiamin is part of the coenzyme TPP (thiamin pyrophosphate) required for two steps in energy metabolism: the enzyme which converts pyruvate to acetyl CoA and for the removal of C from a 5C compound in the TCA cycle.
Pellagra was in epidemic proportions in this country around 1910-1930. What are the symptoms of this disease?
diarrhea, dermatitis, dementia and sometimes death.
What were the dietary conditions which precipitated this disease? What was the significance of a low protein diet?
Populations in low socioeconomic groups in the South consumed most of their energy from corn products. Corn is low in protein (thus tryptophan) plus niacin is found predominately in a bound form of low bio-availability.
What was the significance of a low protein diet?
If you have low protein, you can't convert tryptophan to niacin.
How did our public health officials resolve the situation so that pellagra is now eradicated in this country?
Thus, in 1938 the U.S. mandated fortification of processed grains such as flour and rice with niacin, thiamin, and riboflavin.
If you ate a nice lunch of steak and eggs, which provided 300 mg of tryptophan, how many milligrams of niacin equivalents did this meal provide? How does this compare to the RDA?
5mg of Niacin because 1 mg of niacin = 60 mg of tryptophan. The RDA is 14-16 mg/day.
What nutrients are added to enriched grains?
Iron, Niacin, Thiamin, Riboflavin, and Folate.
Describe in a brief sentence the roles of niacin (NADH) and riboflavin (FADH2) in ATP production.
NAD picks up a H+ in glycolysis and several places in the TCA cycle and carries it to the electron transport chain where each NADH produces 3 ATP and FAD picks up two H+ ions and their electrons in the TCA cycle and delivers them to the electron transport chain where 2 ATP are produced.
What is the UL for niacin?
Why is there no pantothenic acid deficiency in the US?
There is no deficiency because it has a relative abundance in food. Panthos = everywhere.
What is the role of pantothenic acids? That is, describe the importance of pantothenic acid in the conversion of pyruvate to acetyl CoA.
Part of coenzyme A which is used in energy metabolism which helps to produce acetyl CoA.
We get biotin from two sources; explain.
Foods we eat and bacteria synthesized in the GI tract.
Vitamin B6 facilitates the release of energy like other B vitamins, but from protein rather than carbohydrates and fats. Explain.
All 3 forms of vitamin B6 can be converted into coenzyme PLP, which is active in amino acid metabolism because it can transfer amino groups from an amino acid to a keto acid → body can make nonessential (glucogenic) amino acids → which can be converted to glucose.
Compare the RDA and UL for vitamin B6? Why is there a UL? Would you suggest a supplement of 100 mg/day of B6 to your sister who has PMS? Why or why not?
The RDA is 1.3 mg/day and the UL is 100 mg/day. There is a UL because excessive intake can cause neuropathy, nerve damage to the arms and legs. No because a numbers of cases of neuropathy have been reported in women who were taking large doses of B6 supplements for PMS over months or years. In some cases the nerve damage was irreversible.
What is the chemical name for vitamin B12. What does cobalt have to do with vitamin B12?
Chemical Name - Cobalamin. Vitamin B12 contains cobalt.
Explain the statement: Vitamin B12 deficiency causes a folate deficiency.
Vitamin B12 is required to convert folate to its active form, so without it, it can cause a folate deficiency.
B12 Deficiency caused by trouble with absorption.
Symptom of Pernicious Anemia due to folate depletion.
Explain the roles of folate and B12 in blood health. Now describe vitamin B12's second role in the body.
High amounts of folate and B12 help the blood because they break down homocysteine, which leads to heart disease and are necessary to for the production and maintenance of new cells, DNA, and RNA. Second Role - produces nerve tissue, myelin.
Explain the issue which prompted the Food and Drug Administration (FDA) in 1998 to approve the enrichment of flour (and other cereal products) with folate?
Prior to fortification, the U.S. reported about 4,000 cases per year of neural tube defects.
Neural Tube Defect:
malformations of the brain, spinal cord, or both during embryonic development that often result in lifelong disability or death.
Why must women during their child bearing years (even before they are pregnant) be aware of their folate intake?
Spina bifida is caused by incomplete closure of the fetal neural tube at about 28 to 30 days after conception.
Since fortifying the food supply in the US, has the incidence of neural tube defect been reduced to zero?
No, but it has fallen 25-50%.
List foods rich in folate.
Fortified grains, leafy green vegetables, legumes, seeds, liver.
Why are vegan vegetarians at risk for low B12 nutritional status?
it's found primarily in foods derived from animals.
Why does it take years to develop B12 deficiency and only weeks or months to produce folate deficiency?
Because the body recycles much of its vitamin B12, reabsorbing it over and over again, but we aren't able to store/recycle as much Folate.
What are the roles of gastric acid (HCl) and Intrinsic Factor (IF) in B12 absorption?
HCl and Pepsin release Vitamin B12 which bind with the intrinsic factor before being absorbed into the bloodstream of the small intestine.
chronic inflammation of the stomach accompanied by a diminished size and functioning of the mucous membranes and glands.
Why are elderly at risk for B12 deficiency (pernicious anemia)? What are some options on treating pernicious anemia in the elderly population?
HCl and Intrinsic Factor tend to be reduced in older populations resulting in poor vitamin B12 absorption. Periodic injections of B12, B12 nasal sprays, or taking very high doses are now commonly prescribed.
A person suffering from scurvy has pinpoint hemorrhaging in the skin and at points of the body where there is mechanical stress, like on the gums and joints. Why? Discuss the biological role of ascorbic acid and iron to explain this observation.
The symptoms observed reflect the role of vitamin C in collagen formation.Vitamin C helps iron serve as a cofactor in the hydroxylation of proline to hydroxyproline. This step has the effect of cementing the protein matrix of collagen. Without vitamin C and iron, the collagen is weak.
Define a megadose of vitamin C? What is the bottom line on the effect of high doses of vitamin C on the common cold and cancer? List the side effects and negative consequences of chronically consuming high amounts of vitamin C as a daily supplement?
Consuming above 2,000mg a day. There is no evidence that high doses of vitamin C prevent the common cold or prevent/cure cancer. Side effects: gastrointestinal distress, diarrhea, gives false positive or false negative on diabetes, kidney stones and iron toxicity.
How much orange juice must you drink to get your RDA for vitamin C?
3 cups a day.
To meet one's need for vitamin A, rich sources of carotenoid-containing vegetables only need to be consumed a few times each month. Why?
Vitamin A as carotenoids, are readily stored in the liver; thus, they do not have to be eaten daily or even weekly.
Compare plant and animal sources of vitamin A.
Animal sources are rich sources of retinoids that come from liver, fish liver oils, milk, butter, and eggs. Plants are rich sources of carotenoids that come from cantaloupe, carrots, sweet potatoes, broccoli, and spinach.
How many carrots would it take to fulfill your RDA for vitamin A?
A cup of shredded raw carrots.
Describe the role of retinal in the visual cycle by listing the steps in the process of vitamin's A role in the visual cycle.
Vitamin A plays two roles in the eye: it helps maintain a crystal-clear outer window - the cornea - and it participates in the conversion of light energy into nerve impulse at the retina, which contains pigment, rhodopsin.
What is night blindness and why does low vitamin A status cause it?
Night Blindness - slow recovery of vision after flashes of bright light at night or an inability to see in dim light because of vitamin A deficiency.
What is Xeropthalmia? Describe vitamin A's involvement in this form of irreversible blindness by explaining vitamin A's role in epithelial cell differentiation.
Xeropthalmia - progressive blindness caused by inadequate mucus production due to severe vitamin A deficiency. Vitamin A is responsible for maintaining the epithelial cells of the cornea and when there is a deficiency the cornea becomes dry and hard from keratin production.
Why are the World Health Organization and United Nations providing large doses of vitamin A to children throughout the developing world? Describe the connection of vitamin A status and infectious diseases.
Vitamin A deficiency is the leading cause of blindness in children in poorer nations. Also, in the lungs, the epithelial cells begin to harden and lose the ability to ward off diseases which results in pneumonia, measles and other infectious diseases.
Sonia consumed ~2800 µg of vitamin A (~400% of her RDA) as vegetables and one daily vitamin yesterday. Is she at risk of toxicity?
Yes because a multivitamin typically provides 1500 alone which is way over the RDA.
If she ate a pound of carrots on a fad weight loss diet, would she be at risk of hypervitaminosis A?
No because carotenoids in carrots are not associated with toxicity, instead they may just temporarily turn skin yellow.
Recall the definition of UL for Vitamin A.
UL = 3,000 micrograms of RAE/day which is 3-4 times the RDA.
Vitamin D has been described as both a vitamin and a hormone. Explain your answer.
Vitamin D is made in the body after the skin is exposed to UV rays from sunlight, thus theoretically, humans do not have to eat it. But if diets are low in vitamin D and little UV rays hits the skin, humans can show deficiency.
We can synthesize previtamin D in our liver from ___________.
Vitamin D travels to the small intestine to stimulate Ca-binding proteins to aid in the absorption of Ca into the body.
If blood Ca level is low, the kidney is signaled by vitamin D to increase Ca re-absorption, drawing Ca back into the body.
As a last resort, if blood Ca levels are low, vitamin D promotes the release of Ca from bone storage back into blood.
There is 10 micrograms of vitamin D in 1 quart (4 cups) of milk. How does the level relate to the RDA for children and adults?
The RDA for children is 15 micrograms.
How much sunshine weekly and to how much skin surface would you recommend to people who consume no dairy products? How does this recommendation change with individuals with darker skin color? How does living north of 40° latitude (including central Pennsylvania) impact vitamin D needs throughout the year?
Exposing hands, face, and arms to sun for 5-10 minutes, 2-3 times a week should be plenty for good vitamin D status. People with darker skin color require more sunlight than light skinned people perhaps 4 to 6 times longer. People living north of 40 degrees lose vitamin D synthesis for the four months of winter.
Why are elderly at risk for marginal vitamin D deficiency?
With age, the ability to make vitamin D in the skin and convert it to its active form in the kidney has been shown to be reduced. Additionally, older adults in the U.S. are poor milk consumers.
the vitamin D-deficiency in children characterized by inadequate mineralization of bone manifested in bowed legs, knock-knees, and outward-bowed chest.
a bone disease characterized by softening of the bones in the bending of the spine and bowing of the legs. Mostly happens in adult women.
Who is most at risk for rickets now in U.S.? Why is this population at risk? Make one recommendation on how the US could alleviate this public health problem.
Breast-fed infants especially in Southern black populations are most at risk in the U.S. because breast milk is low in Vitamin D. A vitamin D supplement is recommended for breast-fed infants.
Is vitamin K's role in the body as a coenzyme? What is vitamin K's role in the clotting process?
Yes, vitamin K is a coenzyme in the production of protein factors for blood clotting and in the synthesis of a bone protein. It is essential for protein that bind minerals in bones. Also, it activates protein in clotting process so that blood can clot.
Is there risk of low vitamin K status in any human populations in the U.S.? Explain. What has been done in the U.S. to alleviate this problem?
It is very rare because vitamin K is in most foods. When it does occur, it's from fat malabsorption, rare genetic liver diseases, long-term use of antibiotics, and in newborns. In the U.S., newborns are given a dose of Vitamin K to prevent hemorrhagic disease.
Some vitamin K is from a non-dietary source. Explain. Does this non-food source typically meet all of an individual's need for vitamin K?
Vitamin K is also made in an absorbable form by bacteria in the GI Tract. The amount is insufficient to meet the body's needs and bioavailability is limited.
What foods are rich in vitamin K?
Liver, dark green, leafy vegetables, cabbage-type vegetables, and milk.
What is a free radical? Are they normally produced in the body?
An unstable molecule with one or more unpaired electrons. They are produced in the body.
What types of molecules are being protected and why?
DNA and RNA because if free radicals damage them and it leads to a mutation, that could progress into cancer. Also, protein because if damaged, protein response to infection is altered and more inflammation can happen.
What is one positive role of free radicals in the body?
Some free radical-type molecules are needed to destroy harmful bacteria that invades our bodies.
In your own words, describe the role of vitamin E as an antioxidant.
Vitamin E has been shown to reduce oxidation of LDL-cholesterol, known to damage arteries and contribute to development of atherosclerosis and heart disease. It also has a possible role in preventing or delaying cardiovascular disease and cancer.
Now list all the other antioxidants in your diet which are mentioned in Lesson 9.
Vitamin C, Vitamin E, Beta-carotene, Carotenoids, and Fruits/Vegetables.
What are major food sources of vitamin E?
Margarine, salad dressing, dark green, leafy vegetables, wheat germ, whole grains, liver, egg yolks, nuts, seeds, and fatty meats.
One tablespoon of corn oil contains 2-3 mg of vitamin E. How much corn oil is needed to give you your RDA?
The RDA is 15 mg, so you would probably need five tablespoons.
What is hemolytic anemia and who is at risk for developing it?
The condition having too few blood cells as a result of erythrocyte hemolysis in which premature infants are at risk.
Did supplements of beta-carotene reduce or increase incidence of lung cancer in the clinical trial with smokers?
Increased risk in smokers.