With the onset of summer heat, many residents of Spain face not only physical fatigue but also a noticeable decline in mental performance. Difficulty concentrating, forgetfulness, and a feeling of “mental fog”, known as “niebla mental”, often accompany the hot days. This condition is directly linked to the effects of high temperatures on the body. However, as Spanish nutrition experts point out, adjusting your diet can significantly boost cognitive functions and help maintain mental clarity throughout the summer.
The foundation for maintaining brain health is omega-3 fatty acids, particularly docosahexaenoic acid (DHA). DHA is a key structural component of neurons and supports their effective communication. To supply the brain with this vital element, nutritionists recommend regularly including fatty fish such as salmon, sardines, mackerel, or anchovies (boquerones) in your diet. Plant sources of omega-3 include walnuts, as well as chia and flax seeds. Adding a handful of nuts as a snack or incorporating seeds into your morning porridge will help maintain the required levels of these acids in the body.
High temperatures increase oxidative stress in the body, which negatively affects brain function. Antioxidants and polyphenols help counteract this process by protecting neurons and improving cerebral blood flow. Forest berries—such as blueberries, blackberries, and raspberries—are especially rich in these compounds. The flavonoids they contain have been proven to improve memory. Green tea, pomegranate, dark grapes, and turmeric also possess strong antioxidant properties, with turmeric’s effectiveness enhanced when combined with black pepper. Dark chocolate (with at least 85% cocoa content) deserves special mention—not only does it enhance oxygen supply to the brain, but it also boosts serotonin production, the so-called “happiness hormone.”
To maintain a high level of concentration, choline is essential. This substance is a precursor to acetylcholine—a neurotransmitter that plays a central role in attention and learning processes. Adequate choline intake is also linked to a reduced risk of developing depressive conditions. Main sources of choline include egg yolks, broccoli, various types of cabbage, and beef liver. Therefore, an omelette for breakfast or a salad with broccoli for lunch are simple and effective ways to support concentration.
B vitamins (B1, B6, B9, and B12) are essential for brain energy metabolism and neurotransmitter synthesis. In summer, when fatigue tends to intensify, their role becomes especially important. These vitamins are found in oats, brown rice, buckwheat, eggs, spinach, chard, asparagus, legumes, sardines, and mussels. A balanced diet including these foods can help combat mental fatigue.
The brain is one of the main consumers of glucose in the body, using about 20% of the total amount. Sharp fluctuations in blood sugar levels lead to a decrease in mental performance. To ensure a steady supply of energy, it’s best to choose foods with slow-digesting carbohydrates: whole grain oats, leafy greens, nuts, seeds, legumes, and wholemeal bread. It’s important to avoid simple sugars and highly processed foods, which cause sudden glucose spikes.
Even mild dehydration can significantly impair concentration. Experts recommend consuming at least 1.5 liters of water per day, increasing this amount in particularly hot weather. Water with natural electrolytes can also be a good addition. Minerals are equally important: magnesium (seeds, spinach, almonds), zinc (seafood, pumpkin seeds, cashews), as well as iron and iodine (seafood, nori seaweed, eggs).
There is also a simple technique for a quick brain “reboot” known as the “coffee nap.” The method involves drinking a cup of coffee immediately before a short daytime nap (15–25 minutes). You wake up just as the caffeine starts to take effect. This approach simultaneously reduces levels of adenosine, which causes drowsiness, and activates alertness receptors, significantly boosting concentration and improving memory.
As an example of a balanced summer lunch to maintain productivity, nutritionists suggest the following option. Main course: lentil salad with spinach, boiled egg, sesame seeds, and a dressing of olive oil with turmeric. For dessert — a couple of pieces of dark chocolate (85%) and a handful of fresh blueberries.
