Greek yogurt shows as red but regular yogurt as well as Quark are green. Can you explain what the difference is that makes me react to Greek Yoghurt but not the other two?

Greek yogurt is known to contain a higher protein content than regular yogurt.

Equally, quark is known to contain more beneficial strains of bacteria than greek yogurt and this may be a reason. Also, quark contains less calcium than Greek yogurt. While you may be thinking it may be better to consume foods that contain "higher" nutrient counts, the body may not be able to handle the excess nutrients which can cause cellular malfunctioning. When we look at the body holistically it may well be due to an imbalanced gut biome, yeast or candida overgrowth, a toxin or heavy metal build-up, or insufficiency of digestive enzymes.