It's AICR's 30th Anniversary and we're taking a look back and seeing what's next in the research of diet, weight, and physical activity to cancer risk.
When AICR was founded in 1982, the idea that we could reduce our risk of cancer through what we eat, weigh, and how much we move was a novel idea. That was also the year the National Academy of Sciences published their landmark Diet, Nutrition and Cancer report, which stated there was evidence of a link. With awareness and new funding opportunities, the field of lifestyle and cancer prevention burgeoned.
Today, AICR has funded hundreds of innovative research grants in this area and published systematic reviews and updates of the evidence. Improved technologies, research methods and scientific advances have all pushed the field forward relatively quickly.
Research now clearly shows that Americans can prevent approximately one-third of the most common cancers by maintaining a healthy weight, eating a healthy diet and engaging in regular physical activity. Additional prevention comes from avoiding all forms of tobacco, a key part of a cancer-protective lifestyle.
Looking forward and looking back, here are four highlights of the research:
In the late 1980s and early 1990s, more and more lab studies began to show that dietary compounds play a key role in slowing or preventing cancer growth. In 1992, an AICR grantee isolated and identified sulforaphane, a phytochemical in broccoli and other cruciferous vegetables. Since then, scientists have identified thousands of phytochemicals that offer health benefits.
Yet the focus on single nutrients and "superfoods" has now shifted to whole foods and eating patterns. Population studies continuously show that people who eat diets high in plant foods and low in red meat have reduced cancer risk, and lab studies increasingly reveal that a food's compounds act together to fight cancer.
Read more about synergy and whole foods.
Researchers have studied fiber and cancer risk for a long time. There is still a lot to learn about the link; in May 2011, the AICR/WCRF Continuous Update Project report on colorectal cancer found that the evidence that foods containing fiber offer protection against colorectal cancer has become stronger over the years. The report found that for every 10 grams of fiber consumed daily – slightly less than a cup of beans – the risk of colorectal cancer was reduced by 10 percent.
Last month, a review of the evidence funded by WCRF/AICR found that high fiber diets may also protect against breast cancer. For every 10 grams of daily dietary fiber, the risk of breast cancer was 5 percent lower.
There are several possible explanations as to how dietary fiber may prevent cancer. One way may be helping with weight control – a known risk factor for postmenopausal breast cancer and colorectal cancer. Research is ongoing.
AICR's expert report and its updates concluded that regular moderate physical activity lowers the risk of several cancers, both independently and by preventing weight gain. Physical activity is linked to lower risk of colorectal, breast and endometrial cancers.
The evidence suggesting physical activity plays a key role in reducing cancer risk continues to grow. And an emerging field of sedentary behavior now suggests that inactivity – independent of activity – may actually increase cancer risk. Inactivity may influence energy metabolism, sex hormone levels and inflammation – all factors that play a role in cancer risk.
At the last AICR Research Conference, leading experts highlighted the new research on activity and inactivity; read more about it in the AICRBlog.
Unraveling the human genome a decade ago spurred several new fields of study. Among them is the field of nutrigenomics – how our genes influence our responses to nutrients. Each person has thousands of single-letter variations in their DNA, and many of these "misspellings" are involved in metabolism. One such genetic variation, for example, rids the body of dietary isothiocyanates, compounds found in cruciferous vegetables that play a role in cancer prevention. This suggests that some people would benefit more than others from the cancer-protective effects of broccoli.
Then there's the microbiome; the trillions of bacteria living in our gut that regulate digestion and metabolism. Last year, a study published in Nature catalogued the gut microbiome at 3.3 million microbial genes, outnumbering previous estimates for the entire human body. The microbiome may influence inflammatory bowel disease, linked to an increased risk of colon cancer, and many other diet-cancer interactions.
Read more about the microbiome.
Meanwhile, the diet-cancer field now also includes: proteomics, the study of proteins; epigenomics, the study of changing gene expression without altering our DNA; and metabolomics, the study of metabolites in foods.