Spain has been experiencing temperatures well above average for days. Cities are sweltering, humidity is oppressive along the coast, and the dry interior makes every outing feel like an extra effort. In this context, moving around takes a greater physiological toll than usual, and the nutrients the body needs to recover and stay healthy are under increased strain.

DHA, the long-chain Omega-3 fatty acid that forms a structural part of the brain, nerves, and cell membranes, is one of those nutrients. Not because it’s a sports supplement in the conventional sense, but because it acts on the processes that heat and physical exertion most directly alter: inflammation, oxidative stress, and cognitive function under fatigue.

This article isn’t just for athletes. It’s for anyone who’s active, takes care of their body, or simply lives in a country where summer demands more than it seems.

What the heat does to your body before you start exercising

The human body maintains its internal temperature within a very narrow range. When the environment heats up, it activates its main cooling mechanism: sweating. Sweat evaporates on the skin’s surface, and this evaporation draws heat away. The system works well, but it has an important limit: it needs the sweat to be able to evaporate.

This is where the type of heat matters more than we usually think. In a dry environment, like the interior of the Iberian Peninsula in summer, sweat evaporates quickly and cooling is efficient even when the thermometer reads 40°C. In a humid environment, like the Mediterranean coast or the Cantabrian coast on sweltering days, the air is already saturated with water vapor and evaporation slows down. The body responds by producing more sweat to compensate, but this additional sweat doesn’t cool the body because it doesn’t evaporate. The result is a much greater loss of fluid at temperatures that, on paper, seem more moderate.

This has specific and interconnected physiological consequences. The first is dehydration, which occurs more rapidly and is harder to perceive in humid environments because the feeling of overheating doesn’t always correlate with the temperature reading. The second is the loss of electrolytes, especially sodium, potassium, and magnesium, which are eliminated through sweat and are essential for muscle and nerve function. The third, less well-known but relevant, is hemoconcentration: when blood volume drops, everything circulating in the blood, including inflammatory metabolites and products of cellular damage, becomes concentrated. The internal environment becomes more aggressive.

And we haven’t even added the exercise yet.

When physical effort is added

Physical activity generates inflammation. Not in the pathological sense of the word, but as part of the normal adaptation process: muscles undergo micro-tears, the immune system responds, and this controlled inflammatory response is what allows for recovery and improvement. The problem is that this process consumes antioxidant resources and generates free radicals, unstable molecules that damage cells if they are not neutralized in time.

Heat, and especially humid heat, amplifies this process. The hemoconcentration we described earlier also concentrates the products of oxidative damage. The body works harder to thermoregulate, which increases oxygen consumption and the production of free radicals even before the muscle has made a significant effort. In practice, this means that someone who goes for a 40-minute walk at 9 a.m. in August in Valencia is subjecting their body to oxidative stress comparable to that of a more demanding workout under normal thermal conditions.

DHA is one of the fatty acids most vulnerable to oxidation precisely because its molecular structure, with six double bonds, is highly reactive. But this same reactivity is what allows it to be a precursor to anti-inflammatory and neuroprotective molecules. When DHA intake is adequate and of high quality, the body has the raw material to produce compounds that curb excessive inflammation and protect cell membranes from accumulated damage. When this intake is insufficient, the balance tips toward damage.

The role of DHA in recovery and performance

Evidence on DHA and physical activity has been consolidating in recent years in several directions.

Regarding post-exercise inflammation, several studies have documented that DHA supplementation reduces inflammatory markers after intense exercise, including interleukin-6 and TNF-alpha, and that this effect translates into faster recovery and less delayed onset muscle soreness (DOMS) [1,2]. The goal is not to eliminate inflammation, which, as we have seen, is part of the adaptive process, but rather to prevent it from becoming prolonged or amplified beyond what is necessary.

Regarding cognitive function, sustained heat increases what physiologists call the cognitive load of perceived exertion: the brain works harder to maintain attention, coordination, and decision-making under heat stress. DHA is the main structural fatty acid in nerve tissue, and its availability influences the efficiency of nerve transmission and the stress response [3]. This is relevant not only for competitive athletes but also for anyone driving, working, or caring for others during a heat wave.

Regarding cardiovascular function under exertion and heat, DHA helps maintain the fluidity of red blood cell membranes, which facilitates oxygen transport to tissues under conditions of hemoconcentration [4,5]. This is a minor benefit under normal conditions, but it becomes more important in summer when the body is under greater circulatory demand.

Needs change with life stage, not just with age.

Talking about age ranges in nutrition makes more sense when it’s based on the major changes the body undergoes throughout life, not on arbitrary figures. From that perspective, there are four periods when the relationship between physical activity, heat, and DHA deserves specific attention.

Childhood and adolescence: the body that is built

Children and teenagers who play sports are putting their developing bodies under extra strain. Thermoregulation in children is less efficient than in adults: they produce more heat per unit of body mass, sweat less, and dehydrate more quickly. In summer, this means that the safety margin before the heat begins to affect performance and well-being is narrower.

DHA at this stage is not just a recovery nutrient: it’s an active component of neurological and visual development that continues well into adolescence. Regular physical activity in the summer, along with good hydration and an adequate intake of Omega-3, helps ensure that this development occurs under the best possible conditions.

Active adulthood: the body that stays

Adults who exercise regularly, whether it’s competitive sports, recreational training, or simply everyday physical activity, have a demand for DHA that varies with the intensity of the effort and with environmental conditions.

In summer, that demand increases.

The good news is that a well-nourished adult body has a remarkable capacity for adaptation. The bad news is that this adaptation requires raw materials, and DHA is one of the nutrients most frequently found below optimal levels in the Western diet, especially in people who don’t regularly consume oily fish.

Perimenopause and menopause: the body that recalibrates

The hormonal changes of menopause alter the inflammatory response, thermoregulation, and lipid metabolism. Women at this stage are especially sensitive to heat, partly because hot flashes already impair thermoregulation, and partly because the drop in estrogen levels modifies how the body manages fatty acids. Maintaining an adequate intake of DHA at this stage, especially when combined with regular physical activity, is supported in the literature for both cognitive function and cardiovascular health [6].

Maturity and active aging: the body that compensates

After a certain age, the body loses efficiency on several fronts simultaneously: the antioxidant response weakens, recovery after exertion is prolonged, and thermoregulation becomes less precise. Older adults are at greater risk of heatstroke precisely because their ability to sweat and redistribute blood flow to cool themselves is diminished.

In this context, moderate and consistent physical activity remains one of the best investments in health, but it requires more care in summer. DHA acts on several fronts: it reduces chronic low-grade inflammation associated with aging, supports cognitive function, and contributes to joint health, making it easier to maintain physical activity without pain interrupting it [7].

Supplementing in summer: what changes and what doesn’t

DHA supplementation does not have a seasonal logic in itself, but summer introduces practical variables that should be taken into account.

The first is storage. DHA is a polyunsaturated fatty acid sensitive to heat and oxidation. Fish oil capsules stored in a car, in a drawer exposed to sunlight, or in a bathroom with high temperatures can degrade and lose effectiveness. In summer, keeping the supplement in a cool, dark place is also important.

The second factor is timing in relation to exercise and meals. DHA is absorbed better in the presence of dietary fat, so taking it with a meal that includes some healthy fat improves its bioavailability. On hot days, when appetite decreases and meals become lighter, this is an important point to consider.

The third, and perhaps most important, point is that DHA supplementation does not replace hydration. The heat and exercise we’ve described require active fluid and electrolyte replacement, which no supplement can provide. DHA works best when cell membranes are well-hydrated and the body’s internal environment is balanced.

Frequently Asked Questions

Do I need more DHA in summer than in winter?

There is no established seasonal recommendation, but physiological reasoning suggests that oxidative stress increases with heat and physical exertion, and that DHA is one of the nutrients the body mobilizes to respond to this stress. Maintaining a regular, high-quality intake throughout the year is more important than adjusting the dosage seasonally. In summer, it is advisable to check the storage of the supplement.

Does DHA improve athletic performance?

It’s not an ergogenic aid in the strict sense; that is, it doesn’t directly increase strength or endurance. Its role is more supportive: it contributes to more efficient recovery, prevents post-exercise inflammation from becoming unnecessarily prolonged, and helps maintain cognitive function under fatigue. In endurance sports or situations of prolonged exertion in the heat, this support can make a practical difference.

Do children who play sports in the summer need supplements?

The primary source of DHA should always be food: oily fish, eaten regularly, meets the needs of most healthy children. If fish consumption is low or irregular, supplementation may be an option to consider with a pediatrician or family doctor, especially for very active children during the summer.

Is there a difference between the heat in Barcelona and the heat in Cordoba in terms of supplementation?

For the purposes of specific supplementation, there is no established differential recommendation. However, from a physiological standpoint, there is a real difference: the humid heat of the coast promotes greater fluid loss at lower temperatures, creating an environment of hemoconcentration and oxidative stress that is more intense than the thermometer suggests. In this context, hydration is more critical, and nutrients that work on inflammation and oxidative damage, including DHA, have more work to do.

When should I consult a professional before taking supplements?

Dietary supplements should always be avoided if there is an underlying health condition, if medication is being taken, or if the person is a child, pregnant, or elderly with pre-existing conditions. Dietary supplements are intended to support a balanced diet and are not a substitute for medical advice in specific situations.

Literature

1. Ramos-Campo DJ, Martínez-Aranda LM, Caballero-García A, Ramos-Álvarez JJ, Carrasco-Poyatos M, Rubio-Arias JA, Ávila-Gandía V. Supplementation of re-esterified docosahexaenoic and eicosapentaenoic acids reduces inflammatory and muscle damage markers after exercise in endurance athletes: a randomized, controlled crossover trial. Nutrients 2020; 12(3): 719. https://doi.org/10.3390/nu12030719
2. De Salazar L, López-Román FJ, Ramos-Campo DJ, Martínez-Aranda LM, Ávila-Gandía V. Oxidative stress in endurance cycling is reduced dose-dependently after one month of re-esterified DHA supplementation. Antioxidants 2020; 9(11): 1145. https://doi.org/10.3390/antiox9111145
3. Guzmán JF, Esteve H, Pablos C, Pablos A, Blasco C, Villegas JA. DHA-rich fish oil improves complex reaction time in female elite soccer players. Journal of Sports Science and Medicine 2011; 10(2): 301–305.
4. López-Román FJ, Martínez-Aranda LM, Ramos-Campo DJ, Ávila-Gandía V, Contreras CJ, Luque-Rubia AJ. Effect of docosahexaenoic acid supplementation on endurance exercise performance in competitive and non-competitive male cyclists. Gazzetta Medica Italiana 2019; 178(6): 411–416.
5. Ávila-Gandía V, Ramos-Campo DJ, López-Román FJ, Martínez-Aranda LM, De Salazar L, Luque-Rubia AJ. Re-esterified DHA improves ventilatory threshold 2 in competitive amateur cyclists. Journal of the International Society of Sports Nutrition 2020.
6. Molfino, A., Gioia, G., Rossi Fanelli, F., & Muscaritoli, M. (2014). The role for dietary Omega 3 fatty acids supplementation in older adults. Nutrients, 6(10), 4058–4072. https://doi.org/10.3390/nu6104058
7. Calder, P. C. (2013). Omega 3 polyunsaturated fatty acids and inflammatory processes: nutrition or pharmacology? British Journal of Clinical Pharmacology, 75(3), 645–662. https://doi.org/10.1111/j.1365-2125.2012.04374.x