This topic contains a solution. Click here to go to the answer

Author Question: Why are dark-skinned children who live in smoggy northern cities likely to develop ... (Read 29 times)

burchfield96

  • Hero Member
  • *****
  • Posts: 610
Why are dark-skinned children who live in smoggy northern cities likely to develop rickets?

Question 2

Differentiate between retinol and beta-carotene and explain what retinol activity equivalents are.



Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
Marked as best answer by a Subject Expert

AaaA

  • Sr. Member
  • ****
  • Posts: 339
Answer to Question 1

Sunlight supplies the needed vitamin D for most of the world's people. When ultraviolet (UV) light rays from the sun reach a cholesterol compound in human skin, the compound is transformed into a vitamin D precursor and is absorbed directly into the blood. Slowly, over the next day and a half, the liver and kidneys finish converting the inactive precursor to the active form of vitamin D. Like natural sunscreen, the pigments of dark skin protect against UV radiation. To synthesize several days' worth of vitamin D, dark-skinned people require up to 3 hours of direct sun (depending on the climate). Therefore, dark-skinned people and those who lack sufficient exposure to sunlight often lack vitamin D.

Answer to Question 2

Beta-carotene is an orange pigment with antioxidant activity. It is a vitamin A precursor made by plants and stored in human fat tissue. Retinol is one of the active forms of vitamin A made from beta-carotene in animal and human bodies. It is an antioxidant nutrient. Foods derived from animals provide the active form of vitamin A, which is readily absorbed and put to use by the body. Foods derived from plants provide beta-carotene, which must be converted to active vitamin A before it can be used as such. The vitamin A precursor, beta-carotene, is naturally present in many vegetable and fruit varieties. For vitamin A precursors, activity is measured in retinol activity equivalents (RAE). It takes about 12 micrograms of beta-carotene from food to supply the equivalent of 1 microgram of retinol to the body.




AaaA

  • Sr. Member
  • ****
  • Posts: 339

 

Did you know?

Every 10 seconds, a person in the United States goes to the emergency room complaining of head pain. About 1.2 million visits are for acute migraine attacks.

Did you know?

Vaccines cause herd immunity. If the majority of people in a community have been vaccinated against a disease, an unvaccinated person is less likely to get the disease since others are less likely to become sick from it and spread the disease.

Did you know?

Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.

Did you know?

It is widely believed that giving a daily oral dose of aspirin to heart attack patients improves their chances of survival because the aspirin blocks the formation of new blood clots.

Did you know?

Intradermal injections are somewhat difficult to correctly administer because the skin layers are so thin that it is easy to accidentally punch through to the deeper subcutaneous layer.

For a complete list of videos, visit our video library