One Glass, Many Effects: How Dose Determines Whether Wine and Other Substances Heal or Harm

In the 16th century, Swiss physician Paracelsus introduced a concept that remains central to modern toxicology: nothing is poison and everything is poison, because only the dose makes the difference. This idea, often summarized in Latin as “Sola dosis facit venenum,” continues to shape how scientists and health professionals understand the effects of substances on the human body. The principle applies not only to medicines and chemicals but also to everyday foods and drinks, including wine.

Wine has been part of daily life in many Mediterranean regions for centuries. It appears at family celebrations, regular meals, and tourist activities, reflecting a connection that goes beyond gastronomy. However, this relationship only makes sense when approached with moderation. Excessive consumption is known to cause harm to the liver, nervous system, and overall well-being. Paracelsus’s theory helps explain why a single glass of wine at lunch can fit into a balanced lifestyle, while higher intake leads to health problems.

This same logic applies to many substances people consume regularly. Vitamins are essential for basic functions like immune defense and cellular metabolism. Yet, when taken in large amounts—especially through supplements—they can cause digestive issues, liver damage, or neurological disturbances. Coffee is another example: it provides energy and improves alertness but can lead to insomnia, anxiety, and stomach problems if consumed in excess. Even olive oil, a symbol of the Mediterranean diet, adds more calories than many realize and can disrupt nutrition if used without restraint. Water itself is vital for life but can be dangerous if drunk in extreme quantities over a short period; this can cause hyponatremia, a condition where sodium levels in the blood drop dangerously low.

Some substances often seen as harmful also have clear roles when used in moderation. Table salt is necessary for fluid balance and nerve transmission but raises blood pressure when overused. Medicines sold in pharmacies follow the same rule: their active ingredients would be harmful in large doses but help treat pain, infections, or other conditions when taken as prescribed.

In all these cases, the right amount turns a substance into an ally; too much makes it a burden for the body. Paracelsus’s phrase captures this mechanism simply and directly.

When it comes to wine, this approach suggests that drinking should not be seen as permission for uncontrolled consumption but as a custom that can fit into a responsible lifestyle. In Spain, wine production is supported by protected designations of origin and a long rural tradition. It forms part of the country’s cultural and gastronomic heritage. Many studies have examined how a glass of red wine with lunch fits into balanced diets—especially in areas where wine accompanies meals rich in vegetables, legumes, fish, and olive oil. In these cases, moderate consumption becomes one element of a broad and varied eating pattern.

In recent years, researchers have studied the link between wine and cardiovascular health. While findings continue to evolve and must be interpreted with caution, several studies suggest that moderate intake—combined with an active lifestyle and balanced diet—may be associated with better arterial health in adults. This effect is thought to come from natural compounds found in grapes. However, experts stress that these benefits only appear at specific doses and should not be used as an excuse to drink more.

Wine fits well at the table when paired with food, sipped slowly, and limited to small amounts per day—often no more than two small servings for men and one for women, depending on age and physical condition.

Wine culture is also alive in producing regions where wineries, cooperatives, and wine routes attract visitors. These places teach how grapevines depend on soil, climate, and careful farming. Many tours include lessons on tasting techniques, grape varieties, and production methods. Moderation is emphasized during these experiences because it allows people to appreciate flavors calmly while avoiding negative effects from overindulgence. Winemakers themselves often say that drinking less but better helps people value the work behind each bottle.

Paracelsus’s idea has lasted through centuries because it remains relevant today. The dose makes the difference between benefit and harm—at the table, in the pharmacy, or at the winery. This rule shapes how people view substances that have accompanied humanity for generations. Wine continues to play a role in celebrations, family gatherings, and quiet conversations when enjoyed moderately as part of a broad gastronomic culture—and always with responsibility.