Is bolded "less" right? Shouldn't it be more?
Now, let's suppose we did our cross-sectional study and found that the cholesterol content of adults' diets decreased with age. We would then like to know why this is so. One possible answer is that people change their diets as they get older because they feel more vulnerable to heart disease. So we asked the oldest group, using the retrospective approach, if they feel more vulnerable and eat less high-cholesterol food today than they used to. Sure enough, they said yes. But another reason for the current age differences in diet could be that the older adults never ate diets as high in cholesterol as those of the younger adults. So we asked the oldest group to describe the diets they ate 10 or 20 years ago. The diets they described contained less cholesterol than their current diets (which we already knew) and the current diets of the 35- and 45-year-olds in our study! This finding reflects the fact that the older subjects grew up at a different time, when food preferences or availability may have been different.
Sarafino, E. P., & Smith, T. W. (2014). Health psychology: Biopsychosocial interactions. John Wiley & Sons.