The diets of many cancer survivors do not meet 2010 dietary guidelines set by the US Department of Agriculture, and many many survivors eat poorer-quality diets, more empty calories, and less fiber than the general population.
The findings come from the first study to look at dietary intake among cancer survivors in a nationally representative sample of US residents. It was published online October 13 in Cancer.
“These findings reinforce the need for dietary intervention in this high-risk population,” commented first author Fang Fang Zhang, MD, PhD, of the Friedman School of Nutrition Science and Policy at Tufts University, in Medford, Massachusetts.
“Nutrition is one of the cornerstones for cancer prevention and control. Unfortunately, nutrition is not typically integrated into the delivery of optimal care for cancer patients,” Dr Zhang said.
Better nutrition could help protect cancer survivors from other chronic illnesses, potentially improving their long-term health and survival, she suggested.
“It is important to note that cancer survivors have significantly higher chronic disease burden than the general population,” Dr Zhang highlighted. “Improving diet quality can be a particularly important focus for cancer survivors to achieve a long and healthy life.”
Accumulating evidence points to improved survival outcomes in cancer survivors when they meet dietary guidelines compared with those who do not, Dr Zhang pointed out. Current evidence is limited, however, to major cancer types. Few large-scale intervention studies have evaluated the impact of dietary changes and specific nutrients on cancer recurrence and survival. More research is needed in this area, she noted.
Nationally Representative Sample
Data for the study came from people who participated from 1999 to 2010 in the nationally representative US National Health and Nutrition Examination Survey. Researchers looked at dietary intake and quality in 1533 adult survivors of breast, prostate, colorectal, and lung cancer. The patients were matched with regard to age, race, and ethnicity to 3075 people who did not have a history of cancer. The investigators evaluated dietary intake using 24-hour dietary recall interviews conducted in person and over the telephone by trained interviewers. Diet quality was assessed using the 2010 Healthy Eating Index (HEI-2010), in which a higher score indicates better adherence to US dietary guidelines.
The majority of cancer survivors were women (66%) and non-Hispanic whites (83%). Results adjusted for age, sex, and race/ethnicity showed that cancer survivors had significantly lower-quality diets compared with participants who did not have a history of cancer (HEI-2010 total score: 47.2 ± 0.5 vs 48.3 ± 0.4, respectively; P = .03). Cancer survivors ate significantly more empty calories (P = .001) and less fiber (P = .02), which suggests that they got more of their calories from solid fats, alcohol, and added sugars.
The mean dietary intake of certain nutrients in cancer survivors failed to meet federal recommendations: vitamin D (31% of recommended intake), vitamin E (47%), potassium (55%), fiber (60%), and calcium (73%). Survivors also had diets high in sodium (133% of the recommended intake) and saturated fat (112%). Their diets were low in green vegetables and whole grains.
Diet quality improved with age but was worse among those whose education was at the high school level or lower, compared with those with higher levels of education.
Compared with survivors of prostate and colorectal cancer, breast cancer survivors had the highest-quality diets, and lung cancer survivors had the lowest-quality diets (P = .008 and P = .002, respectively). Current smokers had significantly lower-quality diets than current and former smokers (P < .001).
After adjusting for smoking status, results suggested that the differences in diet quality between cancer survivors and those who did not have a history of cancer may be due in part to smoking, suggesting that as a group, smokers are at particularly high risk with regard to dietary interventions.
Several other factors could also explain the worse-quality diet in cancer survivors, according to Dr Zhang. Cancer therapies could cause food cravings and/or changes in taste preference. These changes could continue after the end of treatment, making it difficult to follow a healthy diet. Emotional distress during and after treatment could also play a role, she suggested. Finally, cancer patients may already have poor-quality diets at diagnosis, and they may continue this pattern after treatment.
“Diets rich in fiber from vegetables, fruits, and whole grains and lower in sodium, solid fats, and added sugars are important dietary targets for cancer survivors,” Dr Zhang advised.
“Given the poor diet quality we and others have found in cancer survivors and the high chronic disease burden in this population, it is becoming imperative to routinely integrate nutrition intervention [into cancer care] to improve the health and well-being of cancer survivors across the care continuum,” she emphasized.
Source: Cancer. Published online October 13, 2015.