This type of hyperpigmentation goes away on its own when the source of the inflammation is gone. I had lots of bright red marks, and they are almost completely gone. I no longer break out (unless I am bad and eat one of my trigger foods on the weekend... *cough*). Foods that are good for your skin are also foods that lower inflammation like dark leafy green vegetables, fish, carrots, beets, curries, egg yolks, and other "clean" foods. Natural gelatin is excellent for skin and I put it in all the soups I make because it helps with healing the body overall. My skin texture is very good, but some pink marks remain though they are quickly fading.

An excellent health tonic that I drink is a beautifully-colored juice made from 5-6 carrots, a beet, and an apple. I have found this juice to be highly anti-inflammatory and have been drinking it every day for several months. It has helped immensely with skin health and radiance as well as improving my winter coloring. I am very fair and I find that it gives me a pinkish golden glow... no doubt from all the colorful pigments in the carrots and beets. If your acne is under control with diet, rest assured the pigmentation will eventually go away. Other types of marks and scarring are often permanent, so count yourself lucky you only have hyperpigmentation.

I doubt anyone could tell how successful diet has been specifically on hyperpigmentation. it fades eventually so long as you stop doing things that cause it like break out. And as Scully said, an anti-infammatory diet reduces breakouts. There are some nutrients that affect melatonin. Niacinimide, for example. But it can be even more affective topically.