"Without fats, even vegetable are less nutritious. Brightly colored vegetables are rich in antioxidant carotenoids. They go better with butter. In 2004, Iowa State University researchers who compared people eating salads with traditional or fat-free dressing found those shunning fat failed to absorb lycopene and beta-carotene, powerful antioxidants that boost immunity and fight cancer and heart disease.
'Fat is necessary for the carotenoids to reach the absorptive intestinal walls,' said the lead researcher, Wendy White. Lycopene is found in tomatoes and beta-carotene in orange, yellow and green vegetables.
The chemistry of fats can explain the long tradition of serving fish with butter and cream. Saturated fats are required to assimilate omega-3 fats, and they make omega-3 fats go farther in the body."
Credited to Nina Planck in her book: "Real Food - what to eat and why"