Dietary intake has been shown to influence the acid-base balance in human subjects; however, this phenomenon is poorly understood and rarely reported for the least well-studied segment of older people in a developing country. The aims of the present study were to: (1) quantify estimates of daily net endogenous acid production (NEAP) (mEq/d) in a sample of otherwise healthy elderly aged 50 years and above; and (2) compare NEAP between the elderly and young to determine the effects of aging, which could contribute to changes in the acid-base balance. Analyses were carried out among 526 elderly and 131 young participants (aged 50-80 and 23-28 years, respectively), all of whom were free of discernible disease, nonsmokers, and not on any chronic medication. Selected anthropometric factors were measured and 24-hour dietary recall was recorded. We used two measures to characterize dietary acid load: (1) NEAP estimated as the dietary potential renal acid load plus organic acid excretion, the latter as a multiple of estimated body surface area; and (2) estimated NEAP based on protein and K. For the young and elderly, the ranges of NEAP were 12.1-67.8 mEq/d and 2.0-78.3 mEq/d, respectively. Regardless of the method used, the mean dietary acid-base balance (NEAP) was significantly higher for the elderly than the young (P = 0.0035 for NEAP [elderly, 44.1 mEq/d versus young 40.1 mEq/d]; and P = 0.0035 for the protein:potassium ratio [elderly, 1.4 mEq/d versus young 1.1 mEq/d]). A positive and significant correlation was found between NEAP and energy, protein, and phosphorus (P < 0.05 for all trends). The findings from this study provide evidence of the relatively higher production of NEAP in older people, possibly as an effect of higher consumption of certain acid-producing foods by the elderly.