Natural (non-alkalized) cocoa powder is pure roasted cocoa beans, with most of the fat removed, and then ground into a fine powder. Cocoa powder is essential a concentration of the cocoa bean without the fat. Since cocoa beans are naturally bitter and acidic, these characteristics are accentuated in cocoa powder. Cocoa is natural acidic and it contains a number of flavanol (flavan-3-ol) anti-oxidants that are thought to be responsible for its cardiovascular health benefits of cocoa. When the cocoa is processed with alkali or Dutch processed, it neutralizes the acidity, and the flavanol content and therefore health benefits are substantially reduced. (https://www.ncbi.nlm.nih.gov/pubmed/18710243)
Contrary to our thinking the darker the color of cocoa (not the cocoa content of a chocolate bar), the more alkalinized and less healthful it is. Raw cocoa is actually a light color. See photo. I attached a picture of the non-alkalinized cocoa I found a Natural Grocers that I use for all my baking and chocolate making. Sorry it is side ways. Can't quite figure that out :-).