A Mediterranean diet and overall healthy eating, rather than a particular group of foods or nutrients, reduce the risk for esophageal cancers—particularly esophageal squamous cell carcinoma (ESCC), according to the September issue of Clinical Gastroenterology and Hepatology.
Although diet has been associated with cancers of the esophagus and stomach, few prospective studies have addressed these associations. Heavy alcohol intake has been associated with ESCC risk, but not with esophageal adenocarcinoma (EAC) or gastric cancer. The consumption of total fruit and vegetables has been correlated inversely with ESCC, but evidence is weak for EAC and gastric cancer. Salt and salted foods are listed as probable gastric carcinogens, but there is little convincing evidence of a role for other dietary items.
Because of the complexity of foods and the likely interaction among components, studies on combinations of multiple nutrients and foods could provide more insight into the association between diet and cancer.
Wen-Qing Li et al. analyzed food frequency questionnaires collected from almost 500,000 men and women who participated in the NIH-AARP Diet and Health Study in the US, and compared them with incidences of esophageal and gastric cancer during almost 10 years of follow up.
However, instead of focusing on individual food items, macro or micronutrients, chemicals, minerals, or other components of food, which can be difficult to interpret and reproduce, they examined pre-defined patterns that represented purported healthy diets: the Healthy Eating Index-2005 and the Alternate Mediterranean Diet Score.
Li et al. found that individuals whose diets were most consistent with either of these indices had substantially lower risk of esophageal cancer. Risk was most greatly reduced for squamous cell carcinoma (49% lower in the highest quintile of healthy diet vs the lowest), but also 25% lower for esophageal adenocarcinoma. There was less evidence for an association between either diet index and gastric cancer.
In an editorial that accompanies the article, Thomas Vaughan says it was notable that, in contrast to the marked inverse associations between the healthy diet indices and esophageal cancers, when individual components of the diets were examined, none were found to consistently reduce risk, except possibly for grains.
Vaughan says that the findings indicate that when it comes to studying nutrition and cancer, it might be best to analyze overall dietary patterns that underlie the presumably large contribution of diet to gastrointestinal and other cancers.
So what is a Mediterranean Diet? Vaughan explains that the United Nations Educational, Scientific and Cultural Organization define the Mediterranean as more of a way of life than a compendium of food items, but one that includes olive oil, cereals, fresh or dried fruit and vegetables, a moderate amount of fish, dairy and meat, and many condiments and spices—all accompanied by wine.
This diet has been reported to improve multiple cardiovascular risk factors and serum markers of inflammation, as well as reduce the concentrations of white blood cells and oxidized low-density lipoprotein cholesterol.
Li et al. conclude that their findings provide health professionals with additional information to encourage the public to adhere to the dietary recommendations for the prevention of esophageal cancers.
Read the article online.
Li W-Q, Park Y, Wu JW, et al. Index-based dietary patterns and risk of esophageal and gastric cancer in a large cohort study. Clin Gastroenterol Hepatol 2013;11:1130-1136.e2.
Read the accompanying editorial.
Vaughan, TL. Diet and upper GI cancers: in search of dark matter. Clin Gastroenterol Hepatol 2013;11:1137-1139.