Quiz
Tap a question to see the answer
1. What makes a compound a bioactive rather than a nutrient?
It acts on the body but is not essential, so there is no deficiency disease (Figure 1).
2. What is a phenol, and what makes a polyphenol?
An OH group on a benzene ring; a polyphenol has several (Figure 2).
3. Why does red cabbage turn blue when cooked with baking soda?
Its anthocyanins change color with acidity: red in acid, blue-green in alkali (Figure 2).
4. Which food is the main source of isoflavones, and how do they act?
Soy; they act like a weak estrogen (Figure 2).
5. Which polyphenol is the main one in coffee?
Chlorogenic acid (Figure 3).
6. What five-carbon unit are carotenoids and sterols built from?
Isoprene (Figure 4).
7. How do beta-carotene and lycopene differ?
Beta-carotene has a ring at each end and is provitamin A; lycopene is an open chain, red, and not made into vitamin A (Figure 4).
8. How do phytosterols lower LDL cholesterol?
They crowd cholesterol out of the bile mixtures that carry it into gut cells, so less is absorbed (Figure 5).
9. What enzyme makes sulforaphane, and when does it act?
Myrosinase, when broccoli is cut or chewed; hard boiling destroys it (Figure 6).
10. Which receptor does capsaicin switch on, and what cools the burn best?
TRPV1, the heat receptor; milk or other fatty foods (Figure 7).
11. How does caffeine make you feel alert?
It blocks adenosine, the brain signal for sleepiness (Figure 8).
12. What daily caffeine amount does the FDA say is generally safe for healthy adults?
Up to 400 mg, about four cups of brewed coffee (Figure 8).