The Power of Alcohol-Free
Hydration in a heatwave: what it means for ageing
By Anthony
To begin
Heatwaves take a toll on the body, but they do more than that. A study published in Nature Climate Change shows that repeated exposure to heat over two years increases biological age by 8 to 12 days. This effect is comparable to that of tobacco or alcohol on cells. Ageing accelerates measurably, particularly among the most exposed populations. In this context, hydration becomes an essential component of physical protection.
Heat stress wears down cells
Heat affects the body on several levels. It accelerates the degradation of telomeres —the DNA segments that protect the ends of chromosomes. The shorter they become, the more cells lose their ability to divide correctly. Heat also impairs the functioning of mitochondria, which produce cellular energy. This disruption increases the production of free radicals, thereby maintaining constant oxidative stress. Finally, heat alters DNA methylation, a process that regulates gene expression.
These combined effects promote cellular senescence, a state in which cells stop renewing themselves and release inflammatory signals into the body.
Hydration: a biological defence in its own right?
Water helps maintain a stable body temperature and supports all cellular functions.
In high heat, dehydration acts as a risk multiplier. It reduces blood volume, disrupts thermoregulation, and exacerbates oxidative stress. Without sufficient water and electrolyte intake, the body quickly enters a state of imbalance. This affects the heart, brain, kidneys, and overall metabolism. Hydration is not merely an accessory factor: it directly supports the body’s ability to withstand the wear and tear caused by heat.
Not all drinks have the same effect
Most drinks quench thirst in the moment, but their actual effect on hydration varies significantly. Some slow down dehydration and support temperature regulation. Others, conversely, disrupt hormonal mechanisms and increase fluid loss. The presence of sugar, alcohol, or caffeine profoundly alters a drink's effect on the body. During periods of intense heat, making the right choice is far from trivial: it can limit physiological strain and reduce the risk of complications.
Drinks to avoid in hot weather 🚫
Alcohol increases dehydration. It blocks the action of vasopressin, a hormone that limits water loss. The body eliminates more water than it absorbs. This happens quickly, even with a small amount. Alcohol also dilates blood vessels; while this may create a sensation of coolness, it actually promotes uncontrolled heat loss. In high heat, it heightens the risk of fainting, heart rhythm irregularities, and heatstroke.
High-sugar drinks, such as sodas, present another problem. Their sugar concentration draws water into the intestine, which reduces actual hydration. This mechanism, known as osmotic overload, strains the kidneys and leads to a false sense of quenched thirst. Their hydrating power is lower than that of water. When consumed cold, they also disrupt internal thermoregulation.
Drinks that support hydration and recovery ✅
Certain drinks boost the body's ability to handle heat. Milk, in particular, boasts an excellent hydration profile. Its composition of electrolytes, proteins, and lactose allows for slower and more complete absorption than water alone. It also helps replenish sodium and potassium lost through sweating.
Oral rehydration solutions, available in pharmacies, are designed to rapidly correct fluid deficits. They contain a precise blend of mineral salts and glucose, which facilitates the passage of water across the intestinal wall.
Cold herbal infusions, light salty broths, and sugar-free flavoured waters provide effective hydration with minimal side effects.
Made from fruit or plants, non-alcoholic cocktails can also help maintain good hydration, provided they remain low in sugar.
Comparison of drinks in hot weather
Not all drinks affect the body in the same way when exposed to heat. Here is a summary table to evaluate their suitability during a heatwave, taking into account their actual hydrating power and associated risks.
Scroll the table to read all columns.
| Drink | Hydrating power | Risk in hot weather | Recommended? |
|---|---|---|---|
| Water (still or low-mineral) | High | Low | ✅ Essential |
| Milk (skimmed or whole) | Very high | Very low | ✅✅ Excellent |
| Electrolyte solutions (ORS) | Very high | Low (barring contraindications) | ✅✅ In case of heavy sweating |
| Cold infusions (unsweetened) | High | Low | ✅ Yes |
| Low-sugar homemade mocktail | Medium to high | Low to moderate (depending on ingredients) | ✅ Consume in moderation |
| Pure fruit juice (undiluted) | Medium | Moderate (sugar, acidity) | ⚠️ Dilute with water |
| Commercial sodas | Low | High (sugar, osmotic effect) | ❌ Avoid |
| Energy drinks | Very low | Very high (caffeine, sugar, diuresis) | ❌❌ Strictly avoid |
| Drip coffee / espresso | Low to moderate | Moderate (mild to medium diuretic effect) | ⚠️ In small quantities |
| Tea (cold-brewed, low-caffeine) | Medium to high | Low (if unsweetened and low-caffeine) | ✅ Good choice |
| Artisanal kombucha (low sugar) | Medium | Low to moderate (acids, residual sugar) | ✅ Occasional |
| Homemade water kefir | Medium to high | Low (fermented, minerals) | ✅ Natural hydrator |
| Electrolyte-enriched waters | High | Low (good sodium/potassium balance) | ✅ Particularly useful |
| Beer, wine, spirits | Very low | Very high (alcohol = diuresis + vasodilation) | ❌❌ Strongly discouraged |
Building an effective hydration routine for hot weather
During periods of intense heat, the goal is to limit fluid loss and prevent dehydration. Drinking water regularly remains essential, even if you do not feel thirsty. A glass every hour is often enough to maintain balance. Additionally, it is helpful to alternate with electrolyte-rich drinks, such as milk, diluted juice, or certain fortified waters.
The elderly, children, and exposed workers require special attention. In these groups, the sensation of thirst is often diminished, even though fluid needs remain high. It is also important to avoid very cold drinks, which can slow digestion and disrupt thermoregulation.
Creating a hydration routine does not require complex products, but rather choices suited to the situation: frequency, composition, temperature, and the absence of disruptive ingredients like alcohol or excessive sugar.
Several studies show that regular hydration, combined with adequate electrolyte intake, can mitigate the cellular effects of heat stress. While this won’t “rejuvenate” cells, it limits the acceleration of their degradation. Over the long term, these choices have a cumulative effect. Whether over the course of a single summer or several years, proper hydration can genuinely help slow down heat-induced biological ageing.
The impact of heat on biological ageing is now measured, documented, and recognised. It is not merely a matter of seasonal discomfort, but a phenomenon that gradually alters cellular function. In this context, hydration habits play a pivotal role. Choosing the right beverages, limiting alcohol, avoiding unnecessary sugars, and ensuring regular electrolyte intake helps reduce the heat's impact on the body. These are simple, accessible measures that protect the body on a daily basis.