Effects of Alcohol and Sugar on the Immune System

Excessive consumption of alcohol, sugar, and processed foods, combined with a lack of exercise and adequate rest, can significantly impact the immune system, weakening it and increasing vulnerability to infections.

“Summer is usually a time when we relax and enjoy ourselves more, which is great, but overeating, consuming more alcohol, and exercising less can affect our health. In September, it’s common to see an increase in cholesterol, triglycerides, and blood sugar in tests. Additionally, many people notice they’ve gained weight, feel more tired, and, in some cases, have digestive issues. Another major factor is the change in sleep patterns. During the summer, we tend to sleep less or sleep poorly, which also affects how we feel physically and mentally,” says Dr. Mariel Silva, Medical Director at SHA Spain.

These excesses directly affect the immune system. “When alcohol, sugar, or processed foods are overconsumed, and there is insufficient rest, the immune system suffers. These imbalances reduce our ability to defend against infections like colds or the flu, and it’s common for many people to feel more vulnerable after these periods,” explains Dr. Silva.

“In summer excesses, sugar is always the culprit, not fats as was thought for a long time. Sugar causes inflammation and leaves a negative immunological mark on the body. If it only happens for a month each year and the rest of the time people take care of themselves, the body probably won’t lose balance, or they might just gain some weight due to changes in food quality or quantity, but they should immediately return to a healthy lifestyle,” says Dr. Diego Martínez, an expert in regenerative and functional medicine at SHA Mexico.

“Both alcohol and sugar have a proven and direct impact on immune function. In the case of alcohol, excessive consumption weakens our defenses by altering the function of immune cells responsible for fighting infections. It also damages the intestinal lining, increasing gut permeability, known as ‘leaky gut.’ When this happens, bacteria and toxins can pass through the intestinal barrier into the bloodstream, triggering a systemic inflammatory response,” explains Dr. Silva.

Alcohol and sugar not only increase the risk of infections but also promote chronic inflammation in the body, which is harmful to overall health. Alcohol also disrupts the gut microbiota, the beneficial bacteria that protect us from infections and help maintain a healthy immune system.

“On the other hand, sugar promotes chronic inflammation, which is the basis of many diseases, and raises cortisol levels, the stress hormone, further weakening our defenses. Excessive sugar consumption is linked to a constant inflammatory state, meaning the immune system is ‘busy’ fighting this inflammation instead of focusing on defending the body against infections,” adds Silva.

Other factors can also weaken the immune system and make us more vulnerable to infections and illnesses. Dr. Silva and Dr. Martínez mention poor sleep quality, as rest is crucial for the body’s regeneration and proper immune function.

Chronic and prolonged stress also significantly impacts the immune system, weakening defenses and making us more susceptible to infections like colds, flu, or even more serious illnesses.

A lack of physical exercise can also weaken the immune system. Moderate physical activity helps increase circulation of immune cells and reduces inflammation. Conversely, prolonged inactivity can increase the risk of infections and inflammatory diseases.

“A lack of essential nutrients is another important factor. Vitamins such as C and minerals like zinc and selenium are essential for an adequate immune response. If the diet is low in fruits, vegetables, and foods rich in these micronutrients, the immune system will not be able to function at its best. Moreover, as mentioned earlier, a diet high in saturated fats and processed foods can also promote inflammation and compromise the body’s defenses,” explains Dr. Silva.

Smoking is another habit that significantly weakens the immune system. The toxic chemicals in cigarettes damage respiratory tissues, making it easier for viruses and bacteria to enter the body. Air pollution, toxic chemicals, and radiation exposure can also harm the immune system. Prolonged exposure to pollutants triggers chronic inflammation and weakens the body’s defenses.

Depression, anxiety, and other mental health issues are also often linked to weakened immunity. “Emotional well-being is key to a healthy immune response, as prolonged stress and sadness affect the production of hormones and neurotransmitters that influence the immune system,” concludes Dr. Silva.