Abstract 1909: Dietary contributions to buffer therapy
Authors: Maria Ribeiro, Ariosto Silva, Kim Robien, Thomas Sellers, Robert Gatenby, Robert Gillies
Journal: Cancer Research (2011)

Abstract Introduction: We have previously shown that oral administration of alkalinizing pH buffers (e.g. sodium bicarbonate) significantly reduces the development of spontaneous and experimental metastases in animal models. These observations have led to clinical trials in patients. We reasoned that the alkalinizing effect of these buffers could be exacerbated or inhibited by diet. Notably and surprisingly, data on pH buffering of foodstuffs was heretofore unavailable. Thus, we have evaluated the pH and buffering capacity of different food types in an effort to guide prospective trials and to retrospectively evaluate the effect of dietary pH buffers on cancer progression. Methods: To determine the pH buffering capacity of each food type, we have evaluated a comprehensive list of foodstuffs based on the distribution of self-reported intakes on the Harvard Food Frequency Questionnaire (FFQS, https://regepi.bwh.harvard.edu/health/nutrition.html). For each of these food types, we measured pH titrations from the initial pH values until pH &amp;lt; 4.0. From these, we have assigned a “base excess” score, which is the number of excess H+ consumed per 100g dry weight to lower the pH to 4.0, which is the postprandial pH of the distal duodenum. The final “alkalinizing score” normalizes the base excess to FFQS and USDA serving sizes. The alkalinizing score is higher in foods that generate a net absorption of H+. The final contribution to buffering can be measured as a combination of the alkalinizing score and the frequency of these foods in diet. Conclusions: Data on 21 food types to date indicate a wide variety in basal pH and buffering capacity (initial pH between 3.75 and 6.97, and buffering capacity between -2.48 and 18.92 mmoles H+ per serving size). Of all food, dairy products have the highest contribution to alkaline buffering. Skim milk has the highest pH buffering capacity (79.37 mmoles H+/100g dry weight), followed by Swiss cheese (59.12 mmoles H+/100g dry weight) and whole milk (44.68 mmoles H+/100g dry weight). Among vegetables, red leaf lettuce had the highest pH buffering score, followed by asparagus and broccoli (91.74, 59 and 56.07 mmoles H+/100g dry weight respectively). Among fruits, watermelon, cantaloupe and banana (35.09, 30.46 and 13.27 mmoles H+/100g dry weight respectively) had the highest scores. Factoring in the contribution of diet to systemic buffering capacity can potentially reduce the need of oral administration of pH buffers in clinical trials. In the current study, a wide range of basal pH and buffering powers of foods were measured. This may lead to development of dietary components as an adjuvant to buffer therapy. The association of diet and cancer risk has been the subject of extensive research. Additionally, on its own, pH buffering capacity may have potential importance for etiologic research, primary prevention and therapeutic clinical trials. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1909. doi:10.1158/1538-7445.AM2011-1909