People who eat salads have higher serum levels of vitamins C and E, folic acid, and carotenoids, according to a large study of US adults that suggests these nutrients are well absorbed in the body from raw vegetables.
Researchers at Louisiana State University Health Sciences Center in New Orleans based their findings on data from a federal health and nutrition survey of 17,688 US adults between 1988 and 1994. For the study, published in the Journal of the American Dietetic Association, salad consumption was assessed based on intakes of salad, raw vegetables and salad dressing.
The study contributes to the existing body of research showing Americans are not getting enough fruits and vegetables and could serve as a roadmap for supplement formulators to target specific populations not getting enough of the nutrients in question.
"From this analysis we know that one extra serving of salad daily increased levels of a variety of nutrients," concluded the authors led by Dr Joseph Su.
Using the National Center for Health Statistics' interviews and 24-hour recalls from the Third National Health and Nutrition Examination Survey, researchers estimated the nutrient intake of participants. They assessed the relationship between salad consumption, serum nutrient levels and dietary adequacy following National Academy of Science Food and Nutrition Board guidelines.
The sample was divided between 9,406 women and 8,282 men aged 18 to 45 years and older than 55 years were examined over the six-year period.
Each serving of salad consumed was associated with a 165 percent higher likelihood to meet the recommended dietary allowance for vitamin C in women and 119 percent greater likelihood in men. Similarly, increased levels of vitamin B6 were 73 percent for women and 186 percent for men, and vitamin E and folic acid levels rose by 41 percent and 53 percent in the same categories.
The study provides many indicators for dietary supplement manufacturers and marketers. Firstly, it highlights a discrepancy in raw vegetable consumption among African Americans when compared with other groups.
"More nutrition promotion efforts are needed to reach the non-Hispanic African-American community," urged the researchers.
The data revealed consumption of salads or raw vegetables was 10 to 15 percent less among non-Hispanic African Americans than among non-Hispanic whites of the same age and sex.
It would also appear there is an opportunity, if necessary, for formulators to bring more attention to the issue of the nutrient content of raw vegetables versus supplements.
"…controversy exists over whether or not consumption of raw vegetables contributes substantially to nutrient adequacy, due to issues of bioavailability," stated the article.
However, the authors elaborate the public is perhaps not aware of this issue: "Low bioavailability of nutrients from these sources does not appear to be of concern in the population at large," the study said of raw vegetables and salads.
Finally, the study brings to light the nutrient content of vegetables compared with fruits.
While the study cites 4.4 percent of diseases in Europe can be attributed to diets low in fruits and vegetables, it emphasizes the nutrient content of vegetables over fruits.
"Much of the research on diet and cancer points to vegetable consumption being more strongly associated with reduced risk than fruit intakes," wrote the authors."Thus, in terms of broad recommendations and chronic diseases, it may be more important to increase vegetable consumption than fruit consumption."