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"Dietary guidelines are aimed at the improvement of symptoms and / or the best tolerance to treatments, but we cannot say that they have a therapeutic effect". With this premise in mind, Dr. Pedro Robledo, nutritionist of the Dietetics and Nutrition Service at MD Anderson Madrid, has participated in the Program of Activities for Health and Welfare organized by MD Anderson Foundation, this time on "Nutritional supplements to health - their effectiveness or harmfulness”.

Aimed at both patients and their families, the nutritionist clarifies in this course that "we can recommend a certain diet to prevent side effects such as diarrhea caused by chemotherapy, for example, but this does not mean that sometimes it is not necessary to also prescribe a drug to prevent this side effect".

Thus, to the question of what foods to eat and what foods not to eat, the specialist indicates that "the only food guideline with scientific evidence is to adopt a diet that meets the objectives of variability and nutritional and energy adequacy and is as close to the standard as possible, of the Mediterranean diet ". In fact, he points out, in scientific literature there are many examples of nutritional supplements whose results of efficacy and / or usefulness against cancer are contradictory.

Thus, for example, while there are studies that suggest that an increase in vitamin A in the diet may have a preventive effect against some tumors, other studies indicate that this increase in vitamin A could act, instead, as a tumor precursor.

In the same line, there are scientific studies that indicate that soy may have a preventive effect against breast, ovarian and prostate cancer due to its high content of isoflavones but, in turn, there are also numerous scientific studies that indicate a negative effect on those patients who already have the active disease due to the plant estrogen content of this compound. In addition, another of the components of soybean derived from isoflavones, genistein, could have an inhibitory effect on tamoxifen, one of the most used drugs for the treatment of breast cancer.

Another false myth that is discussed during the seminar is the belief that it is better to take raw vegetables because they provide more vitamins when, Dr. Robledo emphasizes, "most vegetables must be boiled so that the beneficial components they contain (antioxidants, minerals, fiber) are bioavailable to the intestine because, raw, the beneficial contribution of vegetables is lower".

As for refined sugar, it is necessary to reduce its high consumption due to the relationship that exists with diabetes and obesity, but we must not forget the beneficial contribution of sugar from fruits and vegetables (fructose), a relationship currently very much in vogue as a result of multiple studies on the intestinal flora and its processes of intestinal fermentation in relation to pathologies such as food intolerance or immunity. The problem in all these studies is their complication when extrapolating these results to the general population. "There may be alterations in the body of a patient that are simultaneously varying the bioavailability of the intestine or other functions," emphasizes the specialist.

In view of this, Dr. Robledo concludes the seminar highlighting the importance of adapting food individually, although he stresses the difficulty of finding what dose could be therapeutic for each cancer patient at a nutritional level. These doses can also vary according to the evolution and stage of the disease, in the same way that a healthy person adapts his/her diet to the different moments in life.

Probiotics for the improvement of the response to oncological treatments

In the same way that progress has been made in the knowledge of nutritional components of food, in recent years there has also been progress in the knowledge that the intestinal flora not only fulfills a digestive function, but also actively participates in the development and in the evolution of diseases in two senses. On the one hand, the intestinal flora can influence the response to treatments and the evolution of the disease itself and, on the other hand, alterations in this intestinal flora can contribute to the development of some diseases.

According to this line of research, MD Anderson Cancer Center has launched a pioneering clinical trial at its hospital to learn how new biological therapies affect the nutritional status and gut microbiota of patients. Apparently, explains Dr. Robledo, one of those responsible for the study, "these new drugs have fewer side effects than conventional chemotherapy, but there were no studies related to malnutrition and we wanted to know what happened and what factors intervene”.

Thus, in a first phase of the study, Dr. Robledo and his team analyzed a total of 268 patients to find out "how these new therapies can influence or modify nutritional parameters in volume and / or activity compared to traditional therapies", The specialist concludes that they did find less involvement at the nutritional level compared to the usual metabolic parameters but, on the contrary, a much more acute affectation of the digestive system.

Once the data were collected, the second phase of the trial was launched in September 2016, which mainly included patients with melanoma, lung cancer or ovarian cancer in different stages and in treatment only with biological therapy. The objective of this second phase is to determine what type of specific alterations occur in the intestinal flora of these patients and if this is related to the nutritional status.

Parallel to this research, at MD Anderson Cancer Houston, they have a line of complementary research that consists of evaluating the efficacy and the response to drugs in relation to the intestinal flora. With these data, points out Dr. Robledo, "it would be possible to determine what probiotic would be effective and we could indicate the patient to regularize and / or normalize the deficit of nonpathogenic intestinal flora, which would result in a better response to treatment”.

In addition to the Houston center, the Department of Molecular Biology at the Faculty of Sciences of the Autonomous University of Madrid (UAM) and the Alberto Sols Biomedical Research Institute, also of the UAM, also collaborates in this research.