The Stomach cancer Pooling (StoP) Project began in 2012 as a consortium of epidemiological studies regarding gastric cancer. The goal of the international team is to “examine the role of several lifestyles and genetic determinants in the aetiology of gastric cancer”. Their latest study shows just how important citrus fruit can be in reducing the risk of cancer.
By conducting a comprehensive analysis of 6,340 cases and 14,490 controls from 15 case–control studies, investigators determined “an inverse association between citrus fruits and gastric cancer”, but also noted key differences based on different populations and several other factors.
“Our pooled analysis within a global consortium of case-control studies indicates and quantiﬁes a protective effect of citrus fruits on both cardia and non-cardia cancers”, explain the authors.
The mechanism beneath this protective response was attributed to flavanones, a class of ﬂavonoids contained almost exclusively in citrus fruits and juices. Hesperitin and naringenin are the two main components, abundantly found in oranges and mandarins, which inhibit human gastric cancer cell proliferation, migration and invasion in a dose- and time-dependent manner.
Administered alongside ABT-737, an antiapoptotic protein B-cell lymphoma blocker, naringenin exhibited significant activity on human gastric cell lines.
High levels of plasma vitamin C were also associated with a lower risk of developing gastric cancer.
Citrus fruit consumption was measured through food frequency questionnaires (FFQs) that asked participants to indicate food and beverage consumption before their diagnosis. These could include data from one, two or even four years prior.
Overall, “the favourable effect of citrus fruits increased progressively until three servings/week and leveled off thereafter”. This would equate to about 150g, though global intake had much variance. Countries like Iran and Greece showed a slightly higher average, of about 200h per week. Interestingly, for the U.S. and Canada, there was a clear preference for juice which accounted for 80% of all intake, rather than fresh fruit.
The paper found that countries like Italy, Mexico, Russia, Canada, showed a lower association to cancer thanks to increased citrus fruit consumption. People of low socio-economic status could benefit more from a diet rich in citrus produce to counteract the negative effects of the lifestyle risk factors. In general, women were more at risk on average than men.
The bottom line of the study is clear, citrus fruit (and greens in general) can protect against serious disease, like gastric cancers.
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