LEDs put out a lot of blue because most of them are based on phosphorescence, and high energy light (blue or ultraviolet) is required to drive the phosphors. It

LEDs put out a lot of blue because most of them are based on phosphorescence, and high energy light (blue or ultraviolet) is required to drive the phosphors. It's possible to make a white LED without phosphors by combining different colored LEDs, but they're not as bright and much more expensive. That's also how you make them color adjustable.