What it is
Carotenoid pigments — lutein and zeaxanthin from greens and egg yolk, lycopene from tomato, astaxanthin from algae — pulled out and sold as supplements or natural colorants.
Why your biology objects
Real, beneficial antioxidant pigments (lutein and zeaxanthin concentrate in the retina and slow macular degeneration) — but here they've been isolated from the food that carried them. Eat the spinach, tomato or wild salmon and it's green; as a purified capsule or added colorant it's a real nutrient doing an industrial job.