Considering that up to two thirds of the human body is composed of water, its supply needs to be regularly replenished. Drinking around eight cups of water a day prevents dehydration and aids numerous essential functions in the body. We all know about the health benefits of drinking enough water, but can water improve longevity and help us to live for longer?

What is longevity?

Longevity, or living beyond the average life expectancy in good health, is determined by multiple factors including location, sex, socioeconomic status, genetics, lifestyle and environment. While most of these factors are difficult to control, we do have some autonomy over the lifestyle factors that influence our own health. With improvements in diet, medical care and social welfare in the past few centuries, people are living longer than ever before with the average global life expectancy increasing from around 30-40 years to over 80 years. Anyone born in the United States today would be expected to live until 78 [1].

However, many people still do not reach old age as their healthy life expectancy is impaired by the effects of age-related disease. The main aim of the longevity industry is to improve health, delay the process of aging and therefore contribute to longer lifespans through the research, development and implementation of longevity interventions. The most effective way we can improve our health and lifespan ourselves is through lifestyle changes, towards the maximum potential human life expectancy – thought to be around 120-150 years old [2].

Water of life

Water is essential to life; it is the habitat where life on Earth originated, and without it, human beings can only survive for a limited number of days [3]. Water is the most important nutrient in the body and performs multiple vital functions; it removes toxins from the body through the liver and kidneys, it helps with nutrient absorption by carrying oxygen and nutrients to cells, it is essential to digestion and helps break down food, it regulates body temperature and water also aids circulation by aiding blood flow. The body cannot store its own supply of water, so its water intake needs to be continually replenished. If not, the body goes into mild dehydration; the blood thickens as histamines are released in order to store water in cells causing symptoms like headaches, lethargy and reduced cognitive function. Water quality is also important, as drinking contaminated or unclean water can introduce pathogens into the body and cause illness [4].

Maintaining a healthy water intake can also improve longevity; indeed, the increase in average life expectancy seen in preceding centuries is partly due to increased access to clean, safe water supplies in high-income countries. It’s clear we need water to survive, and there is some evidence that drinking enough water can help prevent nutrition-related noncommunicable diseases. Good hydration can protect health and longevity by reducing the risk of cardiovascular diseases like hypertension, fatal coronary heart disease and cerebral infarction [3]. Research shows that drinking enough water may also reduce the risk of colon and bladder cancer by 45% and 50% respectively [4].

As we age, the body’s thirst and fluid intake response becomes slightly downregulated, and following water deprivation, older people tend to be less thirsty and drink less replacement fluid than younger people. Therefore, it is helpful for older people to drink water regularly even when they are not thirsty and to slightly increase salt intake when they sweat. Further education in this area could help prevent sudden hypertension and stroke in older people [3].

Good hydration may also benefit the outward signs of aging by protecting the skin. The largest organ in the body, the skin is important in regulating water levels – hence why we sweat when overheated. Skin cells, like all other cells in the body, contain water that helps them to function. The skin consists of about 30% water, contributing to its plumpness, elasticity and resilience. High water intake can offset water lost through the skin and boost skin hydration. While this cannot prevent the formation of wrinkles, which is determined by genetics and damage from the sun, it can increase skin thickness and density, improving its appearance [3].

Ways to drink more water everyday 

It’s clear water holds numerous benefits to health and living longer, and without it, we would not survive. While everyone experiences the occasional feeling of thirst, water scarcity and dehydration do not occur in the day-to-day life of those living in high-income countries. Instead, we generally drink not only to quench thirst, but as part of food (for example, in soups), as stimulants (such as caffeinated tea and coffee) or for pleasure (tipple, anyone?).

It can therefore sometimes be difficult to remember to get the optimum daily water intake, which depends on an individual’s weight, sex and physical activity level. On average, adults are advised to drink around 8 glasses of water per day. While this might seem unachievable, there are several ways to effectively increase your water intake everyday:

• Keep a reusable water bottle by your desk or workspace that will act as a visual reminder to replenish throughout the day.
• Having a glass of water alongside every meal aids digestion and makes you feel fuller, helping to avoid overeating.
• Water is lost through respiration and sweating, especially during exercise so increasing your water intake after a workout is common sense.
• Substituting carbonated drinks like sodas with a glass of water can reduce calorie intake.
• The water in tea and coffee counts towards you daily water intake, so drink these throughout the day, but avoid in the evening.
• Experiment with different flavour infusions to keep water interesting; add refreshing slices of lemon and cucumber or even seeds, or switch to sparkling water.
• Certain whole foods are an additional source of water, so include water-rich foods like cucumber, tomatoes, celery and melon in your diet.

In many ways, water can be considered the most valuable resource on earth. Although water requires continuous replenishment in the body, its benefits to health and lifespan available at the turn of a tap should make staying hydrated a priority.