Steak, trust me when I say a good steak now and again is the healthiest thing for a guy like me, I don't tend to eat enough meat, and need more in my diet, so i been adding mainly chicken, since i started eating more beef, generally steak my mood has risen significantly and I've had more strength, also it tastes soooo good when I make me a steak grilled perfectly seasoned perfectly... mmm... but yeah not too much but a good amount is a great way to keep certain systems in your body working properly.
Least in my research, and trust me, I've DONE research, changed my diet so many times in so many ways, my energy flags badly, I feel weaker and I start getting depressed to a seriously worrying degree if I cut meat outa my diet, yeah you CAN supposedly replace it with soy, or vegetable proteins, but that never worked for me when I did it...