Water is a great solvent. It’s neutral and doesn’t provide any strong positive or negative effects. It just helps components to mix better and to transport active components.
Xanthan Gum is used as a thickener or rheology modifier and emulsion stabilizer. It doesn’t provide any notable skin-related effects and is used mostly for formulation purposes. It makes the product’s texture smooth and even. It’s a naturally-derived thickener. Notable fact: it can also be found in the food you eat every day, so it is 100% safe.
Vitamin C is known for its strong antioxidant activity. It helps to slow down aging processes. The other positive effect of this ingredient is that it helps to make skin tone even. It's a great ingredient to counter dark areas and uneven skin tone. It's well-researched and considered safe. But it's acid and can irritate the skin if used too often.
Betaine is used a lot in “organic” skincare products. It is a good moisturizer that not only hydrates the skin but also strengthens the cell membrane. This helps to lower the water loss over time. It also softens the skin and reduces irritation and redness. It’s often used at a 3-5% concentration depending on the product.