Human genes have changed little from those of our ancestors 40,000 years ago, but living conditions and lifestyle have changed significantly. Evolutionary studies show that the hunter-gatherer’s diet of our ancestors was rich in PUFAs with a n-3/n-6 ratio of approximately 1–2/1. In contrast, the modern western diet is characterized by consumption of high amounts of saturated fats, trans-fatty acids, and n-6 PUFAs and a low intake of n-3 PUFAs. The n-3/n-6 PUFA ratio in the western diet ranges from 1/15 to 1/25. This decrease in the n-3/n-6 PUFA ratio has been associated with development of numerous diseases.