Hydration for health hypothesis: a narrative review of supporting evidence.

PURPOSE: An increasing body of evidence suggests that excreting a generous volume of diluted urine is associated with short- and long-term beneficial health effects, especially for kidney and metabolic function. However, water intake and hydration remain under-investigated and optimal hydration is poorly and inconsistently defined. This review tests the hypothesis that optimal chronic water intake positively impacts various aspects of health and proposes an evidence-based definition of optimal hydration. METHODS: Search strategy included PubMed and Google Scholar using relevant keywords for each health outcome, complemented by manual search of article reference lists and the expertise of relevant practitioners for each area studied. RESULTS: The available literature suggest the effects of increased water intake on health may be direct, due to increased urine flow or urine dilution, or indirect, mediated by a reduction in osmotically -stimulated vasopressin (AVP). Urine flow affects the formation of kidney stones and recurrence of urinary tract infection, while increased circulating AVP is implicated in metabolic disease, chronic kidney disease, and autosomal dominant polycystic kidney disease. CONCLUSION: In order to ensure optimal hydration, it is proposed that optimal total water intake should approach 2.5 to 3.5 L day-1 to allow for the daily excretion of 2 to 3 L of dilute (< 500 mOsm kg-1) urine. Simple urinary markers of hydration such as urine color or void frequency may be used to monitor and adjust intake.

Understanding Attitudes to Change to Healthier Hydration Habits: The Case of High Sugar: Low Water Drinkers in Mexico.

Adults consuming sugar-sweetened beverages (SSBs) are at increased risk of becoming overweight/obese and developing lifestyle-related diseases. Furthermore, a low water intake is associated with increased health risks, such as CKD. These issues are especially pressing in Mexico where SSB intake is high. The present research aimed to describe the attitudes of Mexican adults who are considered high sugar-low water drinkers (HS-LWDs). HS-LWDs were defined as adults aged 18-45 years, drinking at least 2 servings (500 mL) of SSB/day and maximum 3 servings (750 mL) of water/day. The study included 2.858 HS-LWD (58% males) living in the urban area of Mexico City. Data were collected using an online, self-administered questionnaire. Bayesian approach was applied to analyze attitudes in life and towards drinking. Results showed that social aspects, such as sharing with friends and family and self-image, were the dominant attitudes in life. The main reason to choose a beverage was to get sensations, resulting in 2 axes, one was pleasure oriented and one was health oriented. Getting sensations was also a main driver to drink linked to a moment, together with self-image. The Bayesian network analysis demonstrated 5 attitude profiles, based on the most important attitudes defining each profile: mood and pleasure, self-image and body image, sharing and restoring, pleasure and energy, and health and success. This study allowed describing HS-LWD attitudes, in life and towards drinking. It constitutes a first step in understanding this target group's attitudes and behavior, offering potential recommendations for tailored interventions to promote the adoption of healthier drinking habits.

Effect of Increased Daily Water Intake in Premenopausal Women With Recurrent Urinary Tract Infections: A Randomized Clinical Trial.

Importance: Increased hydration is often recommended as a preventive measure for women with recurrent cystitis, but supportive data are sparse. Objective: To assess the efficacy of increased daily water intake on the frequency of recurrent cystitis in premenopausal women. Design, Setting, and Participants: Randomized, open-label, controlled, 12-month trial at a clinical research center (years 2013-2016). Among 163 healthy women with recurrent cystitis (≥3 episodes in past year) drinking less than 1.5 L of fluid daily assessed for eligibility, 23 were excluded and 140 assigned to water or control group. Assessments of daily fluid intake, urinary hydration, and cystitis symptoms were performed at baseline, 6- and 12-month visits, and monthly telephone calls. Interventions: Participants were randomly assigned to drink, in addition to their usual fluid intake, 1.5 L of water daily (water group) or no additional fluids (control group) for 12 months. Main Outcomes and Measures: Primary outcome measure was frequency of recurrent cystitis over 12 months. Secondary outcomes were number of antimicrobial regimens used, mean time interval between cystitis episodes, and 24-hour urinary hydration measurements. Results: The mean (SD) age of the 140 participants was 35.7 (8.4) years, and the mean (SD) number of cystitis episodes in the previous year was 3.3 (0.6). During the 12-month study period, the mean (SD) number of cystitis episodes was 1.7 (95% CI, 1.5-1.8) in the water group compared with 3.2 (95% CI, 3.0-3.4) in the control group, with a difference in means of 1.5 (95% CI, 1.2-1.8; P < .001). Overall, there were 327 cystitis episodes, 111 in the water group and 216 in the control group. The mean number of antimicrobial regimens used to treat cystitis episodes was 1.9 (95% CI, 1.7-2.2) and 3.6 (95% CI, 3.3-4.0), respectively, with a difference in means of 1.7 (95% CI, 1.3-2.1; P < .001). The mean time interval between cystitis episodes was 142.8 (95% CI, 127.4-160.1) and 84.4 (95% CI, 75.4-94.5) days, respectively, with a difference in means of 58.4 (95% CI, 39.4-77.4; P < .001). Between baseline and 12 months, participants in the water group, compared with those in the control group, had increased mean (SD) urine volume (1.4 [0.04] vs 0.1 [0.04] L; P < .001) and voids (2.4 [0.2] vs -0.1 [0.2]; P < .001) and decreased urine osmolality (-402.8 [19.6] vs -24.0 [19.5] mOsm/kg; P < .001). Conclusions and Relevance: Increased water intake is an effective antimicrobial-sparing strategy to prevent recurrent cystitis in premenopausal women at high risk for recurrence who drink low volumes of fluid daily. Trial Registration: ClinicalTrials.gov identifier: NCT02444975.

Survival of Lactobacillus casei in the human digestive tract after consumption of fermented milk.

A human trial was carried out to assess the ileal and fecal survival of Lactobacillus casei DN-114 001 ingested in fermented milk. Survival rates were up to 51.2% in the ileum and 28.4% in the feces. The probiotic bacterium has the capacity to survive during its transit through the human gut.