To tell you the truth, I’m skeptical there is much evidence at all that eating or drinking some specific thing is going to have a noticeable, positive impact on your skin. The body is complicated and there is so much we do not understand. To say that you could eat a certain thing or drink a certain ingredient and it will improve your skin is just a gross oversimplification. Unless you have some real nutrient deficiency , there is little evidence that any supplement will be beneficial to you. In fact, there is lots of evidence that suggests long term vitamin supplements do not help healthy people (for example).
But my skepticism and lack of evidence does not mean a good formulating cosmetic chemist can just ignore the whole “beauty from within” trend. Your marketers may well ask you to formulate something for this trend. People are buying it and you are in the business of making products that people buy.
If you are going to wade into this pool of ingested beauty products, you should at least focus on ingredients that might have some positive impact (even if it is unproven).
Here are some reasonable ingredients to consider.
Beauty from within foods / ingredients
Green Tea supplements – According to a recent article published in the British Journal of Nutrition, green tea catechins make their way to the skin and have some ability to protect it from UV damage. Of course, the study was was done on 16 subjects. Hardly definitive research.
Vitamin A – Supposedly will help diminish the appearance of fine lines and wrinkles. You can get them from dairy products.
Vitamin C – It’s an antioxidant found in fruits & vegetables and may be able to boost collagen production. Of course, it has to get to your skin cells to work and there is little evidence that it does.
Vitamin E – Helps fight sun damage.
Berries – Blueberries, blackberries, & strawberries have a high antioxidant content. Theoretically, this could help reduce skin damage from free radicals.
Essential Fatty Acids – You can get these from Salmon, walnuts, flax seed and canola oil. They could improve the health of your cell membranes.
Selenium – Foods like wheat bread and cereals have this mineral in them and they supposedly are a key part of the system that prevents oxidative damage in skin. Most normal diets will have plenty of selenium in them. But a study in the British Journal of Dermatology (2003) found that oral doses could prevent sunburn.
While there is some scientific evidence that these ingredients could help it is important to realize that the evidence is fairly weak. Mostly small, badly controlled studies or laboratory findings that don’t necessarily apply to whole organisms. However, there is enough information about these ingredients, and they are well-known enough for consumers that if you have to develop these types of products, they are a good place to start.