Research Update — April 2021

Hurtado-Barroso, S., Trius-Soler, M., Lamuela-Raventos, R.M., et al.
Vegetable and fruit consumption and prognosis among cancer survivors: A systematic review and meta-analysis of cohort studies
Advances in Nutrition (2020), 11(6), 1569-1582.

ABSTRACT

Background: The number of cancer survivors is growing rapidly worldwide, especially long-term survivors. Although a healthy diet with a high vegetable and fruit consumption is a key factor in primary cancer prevention, there is a lack of specific dietary recommendations for cancer survivors, except in the case of breast cancer [World Cancer Research Fund (WCRF)/American Institute for Cancer Research (AICR) report].

Methods: We have therefore carried out a systematic review and meta-analysis of cohort studies reporting on the associations between vegetable and fruit intake with cancer recurrence and mortality and all-cause mortality in cancer patients. After a comprehensive search of PubMed and Scopus databases, the results of 28 selected articles were analyzed.

Results: A high vegetable intake before diagnosis was inversely associated with overall mortality in survivors of head and neck (HR: 0.75; 95% CI: 0.65, 0.87) and ovarian cancer (HR: 0.78; 95% CI: 0.66, 0.91). In ovarian cancer patients, pre-diagnosis fruit intake was also inversely associated with all-cause mortality (HR: 0.82; 95% CI: 0.70, 0.96). The evidence was insufficient for survivors of other cancers, although these associations generally tended to be protective. Therefore, more studies are needed to clarify the association between vegetable and fruit consumption and the prognosis of these different types of cancer.

Conclusion: To date, the general recommendation to consume ≥5 servings of vegetables and fruit per day (∼400 g/d) could underestimate the needs of cancer survivors, particularly those with ovarian tumours, in which the recommendation could increase to∼600 g/d (i.e., 300 g/d of vegetables and 300 g/d of fruit).

INSPIREHEALTH’S INTERPRETATION

The consumption of fruits and vegetables as an important component of a healthful diet is widely accepted and there is evidence to support a protective effect for several types of cancer.  Fruits and vegetables are great sources of fibre, vitamins, minerals and phyto-chemicals (such as carotenoids, polyphenols), all of which have evidence to support their health benefits. In oncology, recommendations for fruit and vegetable intake focus mainly on primary prevention and there are a lack of dietary guidelines surrounding fruit and vegetable intake for cancer survivors. Dietary recommendations for cancer survivors are in parallel with general public health recommendations of consuming a daily intake of five or more servings of fruits and vegetables. Currently, dietary guidelines exist only for breast cancer survivors from the World Cancer Research Fund/American Institute of Cancer Research (WCRF/AICR).

This paper aimed to review the literature and conduct a meta-analysis of 28 cohort studies reporting on an association between vegetable and fruit intake and cancer prognosis, cancer recurrence, site-specific cancer mortality, and overall mortality in cancer survivors. Studies were classified and aggregated by cancer site and included bladder, colorectal, head and neck, gastric, lung, melanoma, non-Hodgkin lymphoma, esophagus, ovarian, pancreas and prostate tumours.  A total of 18,278 participants were included in the review and meta-analysis (an approach that analyzes the combined results of multiple studies) with a follow up period ranging from 9.1 to 16 years.

Overall, the meta-analysis showed a lower mortality associated with vegetable and fruit intake in ovarian cancer patients, and with vegetable intake in head and neck cancer patients.  Although there was insufficient evidence to support fruit and vegetable intake for survivors of other cancers, the authors acknowledged that the associations were generally protective. Furthermore, it is important to note that no studies found a harmful relation with the consumption of fruits and vegetables in cancer survivors.

The study’s findings highlight that cancer sites seem to respond differently to dietary intake and thus require tailored nutrition recommendations. InspireHealth’s dietitians are always available to help explore nutrition that may be most supportive for you through both individual and group programming.

Simple tips to increase your intake of fruit and vegetables:

• Add a savoury breakfast to your routine that incorporates at least one vegetable such as an egg or tofu scramble with peppers, spinach and tomatoes.
• Frozen vegetables are so easy to prepare! Keep a variety on hand and steam them briefly, serving along with your dinner or into a stir fry or stew.
• Cut several fruit and vegetables and serve on a platter before dinner and then take the leftovers into dinner. Both kids and adults alike will love the crunchy snack.
• For lunch and dinner especially, try thinking of half of your plate having different colours of fruit and veggies (heavier on the veggies).
• Keep easy to grab fruit like apples, bananas and oranges on your countertop.

Berries are a delicious way to consume higher amounts of antioxidants and fibre.  Try adding a handful to your breakfast, your salad, or serve a bowl as a snack or sweet ending to a meal.