Even normal butter is an excellent food choice, but grass-fed butter is going to supercharge your diet. Just remember to never buy the synthetic alternative - margarine. Margarine is wholly made out of vegetable oils, and most products do not contain any amount of milk. Real grass-fed butter is a quality source for SFA fats, and it also contains vitamin A, K2, E, and D - all of these vitamins have been linked to increased testosterone production in several different studies. Remember - don't buy margarine.