Study examines relationship between salad consumption and nutrient levels in the bloodstream

Sep 4 2006

A new UCLA/Louisiana State University study of dietary data on more than 17,500 men and women finds consumption of salad and raw vegetables correlates with higher concentrations of folic acid, vitamins C and E, lycopene and alpha and beta carotene in the bloodstream.

Published in the September edition of the peer-reviewed Journal of the American Dietetic Association, the study also suggests that each serving of salad consumed correlates with a 165 percent higher likelihood of meeting recommended dietary allowances (RDA) for vitamin C in women and 119 percent greater likelihood in men.

The study is the first to examine the relationship between normal salad consumption and nutrient levels in the bloodstream, and also the first to examine the dietary adequacy of salad consumption using the latest nutritional guidelines of the Food and Nutrition Board of the National Academy of Sciences.

The findings blunt concerns about the human body's ability to absorb nutrients from raw vegetables, as well as concern that the structure and characteristics of some plants undercut nutritional value.

"The consistently higher levels of certain nutrients in the bloodstream of salad-eaters suggest these important components of a healthy diet are being well-absorbed from salad," said Lenore Arab, visiting professor of epidemiology at the UCLA School of Public Health and co-author of the study with L. Joseph Su, assistant professor at the LSU School of Public Health.

"The findings endorse consumption of salad and raw vegetables as an effective strategy for increasing intake of important nutrients. Unfortunately, we also found daily salad consumption is not the norm in any group, and is even less prevalent among African Americans," Arab said.

"We have so many food choices in this county. Increasing vegetable consumption is a wise strategy for composing a nutrient rich diet," she added. "In fact, our findings suggest that eating just one serving of salad or raw vegetables per day significantly boosts the likelihood of meeting the recommended daily intake of certain nutrients."

The study examined the relationship between reported salad consumption and blood serum nutrient levels, as well as dietary adequacy in pre- and post-menopausal women and men of comparable ages. The research team analyzed dietary data from 9,406 women and 8,282 men ages 18 to 45 and 55-plus contained in the National Health and Nutrition Examination Survey III conducted in 1988-94.

Salad consumption was based on reported intake of salad, raw vegetables and salad dressing. Laboratory measurements determined levels of nutrients in blood serum. Associations between salad consumption and serum nutrient levels were determined using statistical regression models. Measurements were adjusted to account for age, exercise, anti-cholesterol medication, smoking and other variables.