Study under review: Effect of changes in water intake on mood of high and low water drinkers
Water is essential for human health. People that aren’t taking in enough fluids quickly feel the consequences. Research often tries to answer the question: what is “enough” water? What are the results of too little water? Different people have quite a wide range of fluid consumption habits, and optimal fluid consumption has long been an area of debate.
Adults typically have around 60% of their bodyweight composed of water. Water isn’t just essential for basic bodily functions like proper digestion, it may also have an effect on mood and emotional state. Previous research found that fluid deprivation negatively impacts mood under extreme conditions, like extreme dehydration, heat, or intense physical exercise. However, there is only limited data examining the effect of mild dehydration or fluid restriction on mood.
These studies found that mild dehydration caused a decrease in alertness and an increase in fatigue, headaches, and difficulty concentrating. There were also a limited number of trials testing the effect of drinking a specific volume of water on mood and cognitive performance. In one study, participants completed a cognitive test after drinking nothing, 120 mL, or 330 mL of water. When people were thirsty, drinking water improved performance. When thirst was reported as low, water was detrimental to performance. Another study assessing cognitive performance found that drinking 150 mL of water twice, compared to no water (after an overnight fast with no food or drink) had no effect on cognitive performance, though self-reported alertness was significantly higher after water ingestion. However, in another study assessing cognitive performance and mood after a 200 mL drink of water found no differences in mood in the water compared to the no water group.
Based on limited existing data, the researchers hypothesized that:
1) In high volume water drinkers, a decrease in water consumption would have a negative impact on mood, especially aspects of mood that relate to sleep, like fatigue and vigor.
2) In low volume water drinkers, an increase in water consumption would increase alertness and happiness.
Though some earlier evidence suggested these hypotheses were correct, they had yet to be tested in a large, rigorous study. The study under review examined how changes in water intake affected mood states (such as anxiety and happiness) and physiological sensations (such as sleepiness and thirst) in two groups of participants with different habitual fluid intake levels: 2-4L/day, which were considered high volume fluid drinkers (HIGH), and <1.2L/day, which were considered low volume fluid drinkers (LOW).
There is a lack of data on how changes in water intake affect mood. Previous research tended to test the mood effects of more extreme dehydration, and sample sizes were often small.
Other Articles in Issue #02 (December 2014)
- Interview: Bojan Kostevski, MD
Resveratrol and high-intensity interval training
Resveratrol supplementation does not augment performance adaptations or fiber-type–specific responses to high-intensity interval training in humans.
Diet: The whole is greater than the sum of its parts
Discussing the benefits of food (not just supplements) and diet on health, while examining our diet as a whole.
Of mice and guts (and exercise performance)
Effects of intestinal microbiota on exercise performance in mice.
Don’t forget the cocoa
Enhancing dentate gyrus function with dietary flavanols improves cognition in older adults. Research shows that chocolate provides a variety of health benefits — many related to cardiovascular health.
Effects of omega-3s on brain function from infancy to old age
Effect of n-3 PUFA supplementation on cognitive function throughout the lifespan from infancy to old age: a systematic review and meta-analysis of randomized controlled trials.
Gut bugs and fiber: A novel way to keep dyslipidemia at bay?
A systematic review and meta-analysis of the prebiotics and synbiotics effects on glycaemia, insulin concentrations and lipid parameters in adult patients with overweight or obesity.
Vitamin C and E supplementation may hinder strength training
Vitamin C and E supplementation alters protein signalling after a strength training session, but not muscle growth during 10 weeks of training.
Whey and guar gum: unlikely heroes for people with diabetes
Effect of a lose dose whey/guar preload on glycemic control in people with type 2 diabetes- a randomized controlled trial.
Interview: Shou-Ching Jaminet, Ph.D., Cancer Researcher
Shou-Ching is a molecular biologist and cancer researcher at Beth Israel Deaconess Medical Center and Harvard Medical School, and Director of BIDMC’s Multi-Gene Transcriptional Profiling Core.