I think it's not just because of VC. Generally, people with cold constitution are prone to dark yellow. Usually, they can drink some tea soaked in Chinese wolfberry and red dates. I drank it every day for a while, and my skin looked good. But if you get angry easily, you'd better eat less.
If you can, you can drink rice porridge cooked with black rice, brown rice, millet, oats, wheat, buckwheat and barley every morning. My Jiuyang soymilk machine has the function of rice paste, which is very convenient to cook. Chinese medicine says that "grain feeding" can help you supplement the basic elements needed by the human body.
The most important thing is to do more exercise. Exercise can make your blood flow smoothly. As for the way of exercise, you choose. There are yoga abroad, Sabin, Baduanjin and Tai Ji Chuan at home, or simply walking, running and playing ball. The key is to persist.
If you want to make internal adjustment systematically, I suggest you pay more attention to some books on Chinese medicine, or go directly to local Chinese medicine practitioners to find out what kind of physique you are, so that you can make internal adjustment.