Many foods that reduce the risk of cancer are bitter tasting. A study suggests that one may have greater exposure to risk if bitter food sensitivity translates to avoidance of key foods that reduce the risk of cancer.
The study, published last month in the European Journal of Nutrition, was a collaboration between scientists at Pennsylvania State University in the US and University of Leeds in the UK.
Responsiveness to bitter tastes varies between people and falls on a spectrum, says lead author on the study, Joshua Lambert, an associate professor in the Department of Food Science at Pennsylvania State University. Some people, called “non-tasters,” have little or no sensitivity to bitterness, while others, called “supertasters,” have strong aversions to it. In between lies the person with a more moderate response, the “taster.”
These variations in sensitivity often influence our dietary choices and are due to a wide array of influences, including genetic variants called single-nucleotide polymorphisms, or SNPs (pronounced “snips”); cultural and geographic dietary patterns – such as whether Brussels sprouts are regulars on the holiday dinner table; and even age, since we tend to lose bitter taste sensitivity as we get older.
But what we eat and drink play key roles in the development of several types of cancer, including those of the breast, prostate, and gastrointestinal tract. Since many foods with cancer-fighting qualities taste bitter (such as broccoli or coffee), Lambert’s team set out to determine whether people who are sensitive to bitter tastes eat fewer bitter-tasting foods and whether they had increased risk of developing cancer.
The women who participated in the study were a subset of the UK Women’s Cohort Study, a large, ongoing study funded by the World Cancer Research Fund and focused on identifying links between diet and cancer among more than 35,000 women between the ages of 35 and 69 living in the United Kingdom. The subset comprised more than 3,300 women.
The researchers assessed the women’s ability to taste phenylthiocarbamide, or PTC, a chemical often used to study bitter taste sensitivity. Some bitter-tasting chemicals in food, such as the isothiocyanates in cruciferous vegetables, are structurally similar to PTC. Since taste perception is also influenced by genetic factors, a smaller subset of about 750 women underwent testing to determine if they carried SNPs that determined their preferences.
The researchers also gathered data about the women’s biological and lifestyle factors that influence their cancer risk, such as age, body mass index (based on height and weight), dietary patterns (such as vegetarianism), and whether the women smoked or were pre- or post-menopausal.
Each woman completed a food-frequency questionnaire, or FFQ, to report how much and how often they ate certain foods over a specified period. The researchers gathered information about the women’s consumption of fruit (including dried), vegetables (excluding potatoes), red meat, and total meat (including beef, chicken, pork, lamb, and others). The vegetables chosen for inclusion in the FFQ have high quantities of bitter-tasting phytochemicals (such as isothiocyanates) or links to reduced cancer risk.
Information about cancer diagnoses among the women came from the UK’s National Health Service Central Register.
The study’s findings indicated that tasters had a 30 percent greater risk of developing cancer compared to non-tasters but, overall, supertasters did not have a lower risk of developing cancer. However, that risk changed as women aged. Among women older than 60 years, tasters and supertasters had a greater risk (40 percent and 58 percent, respectively), compared to non-tasters.
The data regarding the women’s intakes of bitter vegetables revealed some surprises. “We didn’t actually observe the dietary link that we thought we’d see,” says Lambert, noting that they didn’t find any differences in the women’s intakes of bitter vegetables across the three groups.
These findings suggest that the link between bitter taste sensitivity and cancer risk is complex and may be due to other factors. “People who have greater sensitivity to bitterness might not eat bitter vegetables, but they also might avoid alcohol,” suggests Lambert. Alcohol is linked to several types of cancer.
Lambert’s future studies will investigate the relationship between bitter taste sensitivity, overall diet quality, and specific types of cancers, such as colon, prostate, or breast cancers in male and female cohorts and will be guided by a more holistic approach. “Food and health are related to more than just the bioactivity of the individual food components,” says Lambert. “You have to understand people’s food choices and their relationship to diet in order to make any kind of sensible recommendations.”
This study was funded in part by the World Cancer Research Fund.