Is chewing ice bad for your teeth?
Chewing ice can actually crack • your teeth. Ice is harder than most of the food your teeth have to deal with (even food processors have special blades for crushing ice cubes). The stress can create tiny, hard-to-detect fissures in teeth that can cause pain when you bite at certain angles. If a crack extends through the tooth, it may chip; if the crack reaches the nerve, you may need root canal treatment to save the tooth. You run the same risk when you chew hard candy, popcorn kernels or other extremely hard foods.
Chewing ice poses another risk: Very cold temperatures cause tooth enamel and fillings to contract slightly, and the size change might make fillings come loose.
I’ve heard that eating peanuts can cause cancer. Is this true?
Not really. The FDA tightly regulates the peanut industry to insure that the peanuts you eat contain no significant amounts of the carcinogen aflatoxin.
Aflatoxin is produced by a mold that sometimes grows on peanuts. Studies have linked exposure to this chemical with liver cancer, especially in people with hepatitis, a liver disease.
The toxin, however, isn’t a serious contaminant in the food supply. Processing kills the mold, and even though this doesn’t destroy the entire toxin, peanuts are inspected several times before they reach the market to make sure they contain no more than 20 parts per billion of aflatoxin, a level the FDA considers safe.
Why is an increased heart rate from exercise considered good but a consistently high heart rate considered bad?
When you engage in strenuous exercise, your heart beats faster to pump more oxygen-rich blood to tissues. These workouts strengthen the heart while making your body more efficient at delivering oxygen from the blood to the rest of the body. The long-term cardiovascular benefits of exercising, including a lower resting heart rate, outweigh the risk that the temporary increase in heart rate could lead to a heart attack or other heart problems.
On the other hand, a consistently high heart rate (faster than about 85 beats per minute even when you’re resting) may signal a weak heart straining to perform its task, or other medical problems. Some’ researchers also speculate that a rapid heart rate contributes to atherosclerosis, in which arteries narrow, raising the risk of heart at tacks and stroke.
I keep reading about carotenoids. What are they, and why are they so newsworthy?
Carotenoids are a class of pigments that occur naturally in many fruits and vegetables. Of the 40 to 50 carotenoids in common foods, the best known is probably beta-carotene (found in carrots and many other dark green, yellow or orange fruits and vegetables). Others are alpha-carotene (also in carrots), lycopene (in tomatoes) and lutein (in leafy green vegetables).
These pigments have been getting plenty of press lately for their supposed health benefits. For example, they’re known to boost immune function, and some are used by the body to make vitamin A (necessary for healthy skin, hair, bones, teeth and night vision). Many carotenoids may also lower the risk of heart disease and cancer due to their antioxidant or other healthful properties. But a 1994 study of smokers found a higher rate of lung cancer among those taking beta-carotene supplements, dampening enthusiasm for supplements.
The best strategy, researchers currently believe, is to eat a variety of carotenoids, which may be beneficial on their own and because of their interaction with each other and with other protective substances in plant foods. To do this, eat five servings of fruits and vegetables a day.
I want to make sure no more than 30% of my calories come from fat, but I’m confused by all the numbers on nutrition labels. How do I know how much fat I’m actually eating?
The nutrition label tells you how many grams of fat are in one serving of a food. To calculate how many grams you may eat in a day without exceeding the 30% limit, first estimate how many calories you consume. (American men eat about 2,200 calories a day on average; women, just under 1,600.) Multiply that number by .3 to figure out how many of these calories may come from fat. Then divide this number by nine (one gram of fat has nine calories) to get your daily fat allowance. As long as your total daily intake doesn’t exceed this number, it doesn’t matter whether more (or less) than 30% of an individual food’s calories come from fat.
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