PrepTest 62, Section 2, Question 17
A 24-year study of 1,500 adults showed that those subjects with a high intake of foods rich in beta-carotene were much less likely to die from cancer or heart disease than were those with a low intake of such foods. On the other hand, taking beta-carotene supplements for 12 years had no positive or negative effect on the health of subjects in a separate study of 20,000 adults.
A 24-year study of 1,500 adults showed that those subjects with a high intake of foods rich in beta-carotene were much less likely to die from cancer or heart disease than were those with a low intake of such foods. On the other hand, taking beta-carotene supplements for 12 years had no positive or negative effect on the health of subjects in a separate study of 20,000 adults.
A 24-year study of 1,500 adults showed that those subjects with a high intake of foods rich in beta-carotene were much less likely to die from cancer or heart disease than were those with a low intake of such foods. On the other hand, taking beta-carotene supplements for 12 years had no positive or negative effect on the health of subjects in a separate study of 20,000 adults.
A 24-year study of 1,500 adults showed that those subjects with a high intake of foods rich in beta-carotene were much less likely to die from cancer or heart disease than were those with a low intake of such foods. On the other hand, taking beta-carotene supplements for 12 years had no positive or negative effect on the health of subjects in a separate study of 20,000 adults.
Each of the following, if true, would help to resolve the apparent discrepancy between the results of the two studies EXCEPT:
The human body processes the beta-carotene present in foods much more efficiently than it does beta-carotene supplements.
Beta-carotene must be taken for longer than 12 years to have any cancer-preventive effects.
Foods rich in beta-carotene also tend to contain other nutrients that assist in the human body's absorption of beta-carotene.
In the 12-year study, half of the subjects were given beta-carotene supplements and half were given a placebo.
In the 24-year study, the percentage of the subjects who had a high intake of beta-carotene-rich foods who smoked cigarettes was much smaller than the percentage of the subjects with a low intake of beta-carotene-rich foods who smoked.
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