Health Study: Vegetable Salads, benefits of vitamins B6, B12
Based on the results of the recent health benefits research sponsored by the Association for Dressings & Sauces (ADS) with Dr. Lenore Arab of UCLA, salad, salad dressing and raw vegetable consumption can be an effective strategy for enhancing nutritional adequacy and increasing vegetable consumption in the population at large. The research provides evidence that a salad a day is an important starting point, and each additional serving further improves nutritional status. Studies have shown that the U.S. population is currently not getting enough water-soluble vitamins of which salads are a rich source. Why are these vitamins important? For example, adequate consumption of the vitamin folic acid is linked to lower incidence of neural tube defects and decreased levels of homocysteine concurrent with decreased cardiovascular disease risk.
The study, titled “Salad and Raw Vegetable Consumption and Nutritional Status in the Adult U.S. Population: Results from the National Health and Nutrition Examination Survey III”, was published in the September 2006 issue of the extremely high impact Journal of the American Dietetic Association (JADA)
JADA is the official professional journal of 65,000 professional dietitians that represent basically all registered dietitians in the U.S. and a number abroad, and are responsible for all patient contact -- serving as valuable resources for nutrition information. The paper, authored by Drs Joseph Su of Louisiana State University and Lenore Arab, is an epidemiologic analysis of the U.S. population as sampled in a nationally representative survey. The study presents data on more than 17,000 adults of all races and ethnicities, and both genders. It compares the nutritional status of salad consumers and salad dressing consumers with non-consumers, and shows that consumption of salad is significantly associated with better nutritional status. Nutritional status is assessed using National Academy of Science guidelines for intake, and also is measured using blood measures of fat and water-soluble vitamins and carotenoids. Six important nutrients are higher among the salad consumers, and each serving of salad is related in a dose response fashion to a better level of the vitamin in the blood. The significant and consistently higher serum values of these vitamins suggest that they are being well absorbed from salad. Salad dressing users had significantly greater serum levels of most of the vitamins studied as well, and had a better nutrient adequacy status. It is important to note that, according to a nationally projectable Gallup survey, a vast majority (93%) of those who eat salads indicate they either always or usually use a dressing.
The JADA article presents the details of the study design, population and statistical and epidemiologic analyses, and the willingness of JADA to publish the study attests to the novelty of these results. Although you might assume that salad intake is known to show measurable improvements in nutritional status, some might have argued that the nutrients in these fresh vegetables are not bioavailable and not well absorbed from this source, or that cooking is required for bioavailability. In fact, from emerging research on health outcomes, it appears that consuming fresh/raw vegetables is better than consuming cooked vegetables.
The study is important for a number of reasons including 1) based on prior studies and recent recommendations for intakes, the U.S. population is getting far too little of some of the water soluble vitamins of which salads are a potentially rich source. This is demonstrated in an earlier paper by the same authors where over 80% of U.S. women have inadequate intakes of vitamin C and folic acid (*see figure from that paper in footnote), 2) the effects of salad intake seen in the paper are based on the entire U.S., and are seen in the population at large, not a special subpopulation, and therefore the results are generalizable to all people in the U.S., 3) the effects are significant for each additional serving, and a dose response effect like this lends scientific credibility. Otherwise, it might be argued that salad consumers are just different in general. The paper indicates that each additional serving of salad improves nutritional status, 4) risk groups that are low salad consumers and should be particularly targeted are identified, which will be useful for marketing purposes and focusing on consumers at greatest risk, 5) presenting this information to dietitians is targeting the most impactful professional group available for translating this message to the consumer in their language for behavior changes.
*Arab L, Carriquiry A, Steck-Scott S, Gaudet MM. Ethnic differences in the nutrient intake adequacy of premenopausal US women: results from the Third National Health Examination Survey. J Am Diet Assoc 2003; 103:1008-14.