The USDA sets servings sizes all over the place. But, they allow query of fractional values, and they list calories. Simply adjust the percentage until you get 100 calories in your listing.
Of course an average is simplistic, but it's all I have for now. I'm keeping a food log (4 months now) and will recalculate using my real diet after a year.
In today's world of foods from all over the world, I believe you can devise a diet that meets all the known requirements for a healthy person without supplements. I'm on my way to showing it.
