Today's "Western" diet is characterized on the one hand by a high intake of pro-inflammatory omega-6, and on the other by a low intake of anti-inflammatory omega-3 fatty acids, which leads to their imbalance in the body and increased concentration of various inflammatory mediators. This can predispose or exacerbate many inflammation-related illnesses or have an impact on mental health deterioration. Adequate intake of omega-3 fatty acids through food or supplementation with dietary supplements can optimize the ratio of omega-3/omega-6 fatty acids in the body and have a positive effect on the prevention and reduction of symptoms of inflammatory bowel disease, cardiovascular disease, rheumatoid arthritis, allergies and asthma owing to its anti-inflammatory, vasodilatory and antithrombotic effect. Supplementation with omega-3 fatty acids, especially docosahexaenoic during pregnancy and lactation, improves visual and cognitive functions in children. In addition, a positive effect of omega-3 fatty acid supplementation has been found in depression, ADHD, Alzheimer’s disease and dementia. With this in mind, regular intake of foods rich in omega-3 fatty acids, especially eicosapentaenoic and docosahexaenoic, is recommended in order to achieve a number of positive effects on human health.