The study by first author Danxia Yu, Ph.D., Vanderbilt research fellow, and lead author Wei Zheng, M.D., Ph.D., MPH, director of the Vanderbilt Epidemiology Center and chief of the Division of Epidemiology, was published in the latest issue of the journal PLOS Medicine. Investigators from the International Epidemiology Institute, the Harvard School of Public Health, and Meharry Medical College were also involved in the study.
The investigators analyzed data from the Southern Community Cohort Study (SCCS) which includes 84,735 adults, ages 40-79, recruited from 2002- 2009, mostly through community health centers serving low-income populations in 12 Southeastern states. More than half of the participants had an annual household income of less than $15,000 and 65 percent were African-American.
At the time of recruitment, participants responded to a detailed food frequency questionnaire which noted the types and amounts of foods in their usual diet. For this follow-up study the investigators used the federal government’s Dietary Guidelines for Americans (DGA), and the Healthy Eating Index (HEI) to assess the healthfulness of the participants’ diets. The DGA emphasizes a diet rich in vegetables, fruits, whole grains, seafood, legumes and nuts; moderate in low- or non-fat dairy and alcohol; and low in red and processed meats, sugar-sweetened foods and drinks and refined grains.
Of the 77,572 participants with follow-up information over a mean period of 6.2 years, 6,906 participants died –2,244 from cardiovascular disease, 1,794 from cancer and 2,550 from other diseases. After controlling for factors such as age, weight, exercise, smoking and prior history of some chronic diseases, the investigators found that participants who ate the healthiest diet had an approximately 20 percent lower risk of death from those diseases than those with the least healthy diet.
The authors noted that previous studies have suggested African-Americans and low-socioeconomic adults, especially low-income African-American men, have more limited access to supermarkets and healthy foods and generally lower quality diets. However, few studies have evaluated the association between overall diet quality and disease mortality.
“This is the first study to our knowledge reporting this association in a low-income population that largely comprises African-Americans,” said Zheng, the Anne Potter Wilson Professor of Medicine. “These findings present direct evidence that dietary modification may influence disease prevention in this underserved population.”
Other contributors include Maciej Buchowski, Ph.D., Xiao Ou Shu, M.D., Ph.D., MPH, Xianglan Zhang, M.D., MPH, William Blot, Ph.D., Vanderbilt; Jennifer Sonderman, M.H.S., Joseph McLaughlin, Ph.D., Mark Steinwandel, B.B.A., International Epidemiology Institute, Rockville, Maryland; Lisa Signorello, Sc.D., Harvard School of Public Health; and Margaret Hargreaves, Ph.D., Meharry Medical College, Nashville.
The study was supported by funding from the National Cancer Institute, a division of the National Institutes of Health (R01 CA092447).