Question 1

Which of the following symptoms is associated with consuming a megadose of vitamin C?

Accepted Answer

Consuming a megadose of vitamin C can lead to nausea and diarrhea, as excessive amounts of the vitamin are not well-absorbed and can irritate the gastrointestinal tract. Night blindness is associated with a deficiency in vitamin A; scurvy is caused by a deficiency in vitamin C; erythrocyte hemolysis (destruction of red blood cells) is not a symptom associated with vitamin C consumption.

Question 2

Which of the following foods has the highest concentration of selenium?

Accepted Answer

Brazil nuts are well-known for their high selenium content, significantly more than other foods. Selenium is an essential mineral important for various bodily functions, and Brazil nuts can provide more than the daily recommended amount in just one nut.

Question 3

Which of the following diseases might you notice in an individual who follows a vegan diet and consumes plant products grown in soil with low levels of selenium?

Accepted Answer

Keshan disease is associated with selenium deficiency, which can occur in individuals consuming foods from selenium-deficient soil, including those following a vegan diet.

Question 4

Which of the following would you expect to be the weakest antioxidant?

Accepted Answer

Beta-carotene is a weaker antioxidant than vitamin E, lycopene, and lutein because it has fewer conjugated double bonds. Conjugated double bonds are responsible for the antioxidant activity of carotenoids, and beta-carotene has only 11 conjugated double bonds, compared to 13 for lycopene and 10 for lutein. Vitamin E is also a more effective antioxidant than beta-carotene because it has a hydroxyl group, which can donate a hydrogen atom to free radicals.

Question 5

Vitamin C assists in the formation of the structural protein called:

Accepted Answer

Vitamin C is crucial for the biosynthesis of collagen, an essential structural protein in the skin, blood vessels, tendons, and ligaments. It acts as a cofactor for the enzymes involved in collagen synthesis, stabilizing and cross-linking the collagen fibers.

Question 6

The doctor has recently told Julie that she is anemic. Julie should consume ________ with her iron supplement to increase its absorption.

Accepted Answer

Vitamin C, found in orange juice, enhances the absorption of iron from supplements and plant sources, making it the best choice for someone looking to increase iron absorption.

Question 7

Prakash is a 45-year-old male who has been smoking since he was 12 years-old. He would like to take a beta-carotene supplement to reduce his risk of developing lung cancer. What dose would you recommend?

Accepted Answer

Beta-carotene supplements have been found to increase the risk of lung cancer in smokers, rather than decrease it. Therefore, they are not recommended for smokers like Prakash.

Question 8

Which of the following contains the greatest amount of bioavailable beta-carotene?

Accepted Answer

Lightly cooking carrots can increase the bioavailability of beta-carotene compared to eating them raw or thoroughly cooked. Freezing carrots can also diminish the amount of bioavailable beta-carotene due to the breakdown of cell walls during the freezing process.

Question 9

Which of the following are rich sources of vitamin C?

Accepted Answer

Green and red peppers are rich sources of vitamin C, which is essential for the repair of tissues and the enzymatic production of certain neurotransmitters. Vitamin C is also an antioxidant. Milk, cheese, seafood, and whole grain cereals are not as high in vitamin C compared to fruits and vegetables like peppers.

Question 10

Which of the following is the BEST source of vitamin C?

Accepted Answer

Oranges are well-known for their high vitamin C content, making them an excellent source of this essential nutrient compared to the other options listed.

Question 11

When analyzing the nutritional profile for cooked spinach you read that it contains 6 mg of beta-carotene per 100 g serving. How many mg of vitamin A would this be equivalent to?

Accepted Answer

1 mg of vitamin A is equivalent to 6 mg of beta-carotene.

Question 12

Which of the following is true about absorption of retinol?

Accepted Answer

Retinol, a form of vitamin A, is absorbed in the small intestine. After absorption, it is packaged into chylomicrons, which are lipoprotein particles, and then enters the lymphatic system for transport throughout the body. This process is essential for the distribution of retinol to the liver and other tissues.

Question 13

In general, what percentage of carotenoids are absorbed in the GI tract?

Accepted Answer

Carotenoids, which are important for human health, have a relatively low absorption rate in the gastrointestinal tract, with about 20-40% being absorbed. This absorption rate can be influenced by various factors, including the presence of dietary fat, which enhances their absorption.

Question 14

Which of the following carotenoids can be converted to retinol in the body?

Accepted Answer

Beta-carotene can be converted to retinol in the body, making it a precursor to vitamin A. Lutein and lycopene are not precursors to vitamin A and retinol is already the active form of the vitamin.

Question 15

Which of the following hormones requires selenium for its synthesis?

Accepted Answer

Thyroxine, also known as T4, is a thyroid hormone that requires selenium for its synthesis. Selenium is an essential component of the enzyme that converts the inactive form of thyroxine (T4) to the active form (T3) in the body. A deficiency in selenium can lead to decreased levels of T3 and T4, causing various forms of thyroid dysfunction.

Question 16

Which of the following increases the RDA for vitamin C?

Accepted Answer

Smoking cigarettes increases the body's need for vitamin C because it causes oxidative stress, leading to a higher demand for antioxidants to neutralize free radicals. Therefore, smokers have a higher recommended dietary allowance (RDA) for vitamin C compared to non-smokers.

Question 17

Absorption of which mineral is enhanced by vitamin C?

Accepted Answer

The absorption of iron is enhanced by vitamin C. Vitamin C helps to convert the iron from ferrous to ferric form, making it easier for the digestive system to absorb it.

Question 18

Which of the following foods would be the best dietary source of pre-formed vitamin A?

Accepted Answer

Egg is the best dietary source of pre-formed vitamin A among the options given. Pre-formed vitamin A, also known as retinol, is found in animal products such as eggs, meat, and dairy. Carrots and cantaloupe contain beta-carotene, a precursor to vitamin A, which the body can convert to vitamin A, but it is not pre-formed. Rice generally does not contain significant amounts of vitamin A or its precursors unless it is fortified.

Question 19

Due to differences in absorption and metabolism, how many grams of beta-carotene is equivalent of 1 gram of vitamin A (1 RAE)?

Accepted Answer

12 grams of beta-carotene is equivalent to 1 gram of vitamin A (1 RAE) due to the efficiency of its conversion into retinol, which is less efficient than the conversion of preformed vitamin A.

Question 20

Which of the following is a function of carotenoids?

Accepted Answer

Carotenoids, such as beta-carotene, are known for their role in supporting the immune system by acting as antioxidants and enhancing immune response.

Quiz 11: Nutrients Involved in Antioxidant Function