The proverbial topic of how much water to intake each day indeed seems up for debate.

I’ve listened to various opinions from a range of professional holistic health practitioners, from recommendations to drink two gallons of water a day, to Americans drink too much water, to intaking 40% of one’s body weight in fluid ounces. There seems to be no widespread agreement on what amount constitutes a true physiological need. The issue seems to be further complicated due to the fluid content of foods, which can vary dramatically from person to person depending on their diet, combined with the diversity of health constitutions described by Ayurvedic medicine based on natural distinctions in genetics and environmental conditions.

Let’s examine a body of evidence-based research on whether a person’s health is positively or negatively impacted by their level of water intake. According to Armstrong & Johnson (2018), there is no pervasive consensus on daily human water intake requirements across demographic groups, even though there are physiological and nutritional research terms that describe Adequate Intake (AI) and daily Total Water Intake (TWI, L/24h). The authors acknowledge large inter-individual differences and “dynamic complexity inherent in the human water regulatory network, which involves the central nervous system and several organ systems.” However, they propose a novel way of assessing daily water requirements across all ages and sexes as an alternative to AI values that involves calculating the intensity of a specific neuroendocrine response that is autonomically controlled by the brain. Using plasma arginine vasopressin concentration analysis across data sets, they determined that a “mild neuroendocrine defense of body water commences when TWI is < 1.8 L/24h” and that receiving less than this in 24 hours may be correlated with dysfunctional metabolism and chronic diseases.”

A randomized controlled trial conducted by Nakamura et al. (2020) assessed the effects of increased daily water intake by 550 mL in blood, urine, and saliva biomarkers between two groups. The results found that there was no significant difference in fasting blood glucose and arginine vasopressin levels. However, a significant change in the increased water intake intervention group was reported on the markers of decreased systolic blood pressure and increased body temperature. The authors concluded that habitual water supplementation in the morning and at bedtime “represents a safe and promising intervention with the potential for lowering blood pressure, increasing body temperature, diluting blood waste materials, and protecting kidney function” with more health benefits than a lower amount of water intake.

Perrier (2017) references how critical water intake is for short-term performance and safety as well as vulnerable populations such as the elderly, with multiple studies citing how dehydration is associated with increased mortality in hospitals. The author further references marked differences between low and high water drinkers, with lower water drinkers having significantly lower 24-h urine volume, higher urine concentration, higher plasma vasopressin and higher cortisol levels. These differences suggest that chronic low drinking “triggers a sustained antidiuretic response to conserve body water.” Chronic kidney disease is one health condition cited as being significantly reduced with a higher quintile of fluid intake.

Overall, these research studies all point to the increased health benefits of greater daily water intake across various populations and age groups, along with promising further research and data for continued growth, education, and understanding.

Wishing you the very best of health, healing, and longevity!

In peace,
Whitney

References

Armstrong, L. E., & Johnson, E. C. (2018). Water Intake, Water Balance, and the Elusive Daily Water Requirement. Nutrients, 10(12), 1928. https://doi.org/10.3390/nu10121928

Nakamura, Y., Watanabe, H., Tanaka, A., Yasui, M., Nishihira, J., & Murayama, N. (2020). Effect of Increased Daily Water Intake and Hydration on Health in Japanese Adults. Nutrients, 12(4), 1191. https://doi.org/10.3390/nu12041191

Perrier E. T. (2017). Shifting Focus: From Hydration for Performance to Hydration for Health. Annals of nutrition & metabolism, 70 Suppl 1, 4–12. https://doi.org/10.1159/000462996