Take a cube of butter from your refrigerator, slice it with a knife, and spread it on a slice of bread. Did it coat the bread evenly or did it remain in hard lumps? Researchers have determined that the easier butter spreads, the better it is for your health.
Why is this? The firmness of butter depends on its ratio of saturated and unsaturated fat. At refrigerator temperatures, saturated fat is hard and unsaturated fat is soft, or even liquid. Therefore, butter that is relatively easy to spread has less saturated, artery-clogging fat and more (healthier) unsaturated fat.
In addition, a 2006 study shows that the softer the butter, the more fresh pasture in the cow’s diet. Cows that get all their nutrients from grass have the softest butterfat of all. Butter from grass-fed cows also has more cancer-fighting CLA, vitamin E, beta-carotene, and omega-3 fatty acids than butter from cows raised in factory farms or that have limited access to pasture.
(For more information about the benefits of dairy products from grass-fed cows, read Jo Robinson’s essay, Super Healthy Milk. http://eatwild.com/articles/superhealthy.html
“The Linear Relationship between the Proportion of Fresh Grass in the Cow Diet, Milk Fatty Acid Composition, and Butter Properties.” Journal of Dairy Science, 2006. 89:1956–1969. [Note: this study is available free of charge at the Journal of Dairy Science website.]