Education is playing an increasing role in the quality of our diets, new research indicates, pointing to a much wider gap between the diets of differently educated people compared to 30 years ago.
Dr Barry Popkin and colleagues from the Department of Nutrition at the University of North Carolina at Chapel Hill found that while dietary quality has improved over time, those with more education now have much healthier diets, compared to the 60's when income and education were rarely significant on diet.
"In fact, the gap in diet between higher educated persons and lower educated persons may explain the large disparity in health between higher and lower socioeconomic groups in the United States," Popkin said.
The study, which examined the composition of the diet, not energy intake or obesity, compared dietary habits in almost 6,500 respondents in 1965 and 9,200 in 1994-96.
The research, published in the July issue of the American Journal of Preventive Medicine, showed that in 1965 college-educated people took in more calcium, iron and servings of fresh fruit than less-educated people, but they also ate more saturated fats, which decreased their Dietary Quality Index. Between 1965 and the mid-1990s, the overall Dietary Quality Index improved for all education groups.
But 30 years later, the effects of education are more pronounced - better-educated people not only have better diets today compared to their counterparts 30 years ago, they also eat better than today's high school dropouts. For instance, white men with no high school diploma scored 61.9 on the Dietary Quality Index, while their college-educated peers scored 68.3. A similar gap separated black men in the same educational categories. Income variations produced far smaller differences, said Popkin.
"In general, extra years of schooling related to small upward shifts in diet quality. The highest diet quality level was found among white women who attended college and for those with income far above the poverty line," said Popkin.
But race alone did not always predict results. Black male high school graduates saw no change in their dietary quality scores, while black women with the same level of education saw significant gains.
An exception to the general dietary improvement was a drop in calcium intake, which Popkin blames on reduced milk consumption. Other researchers have noticed the same pattern with calcium, which is needed to build and maintain strong bones. A disappointingly small shift downward in the use of added sugar, discretionary fat, salt and alcohol, was also observed in the survey.
Popkin said that by the 1994-96 survey, people were consuming less fat and cholesterol and more grains and vegetables. But this good news was overshadowed by the increasing prevalence of obesity in the United States, he said.
The Dietary Quality Index research model reflects proportion, variety and moderation in diet, but does not account for total energy intake, Popkin said. So while it showed a lower percentage of calories coming from fat (a sign of dietary improvement) because the consumption of fats remained constant, total calories increased, leading to a net weight gain.
Exactly why more education is linked to better diets is not clear, but Popkin suggests it may be caused by "a diffusion of knowledge, skills, attitudes and beliefs that occur while individuals are participating in the educational system".
"Improving the education system in the United States may help to eliminate disadvantages in diet quality," he added.