A healthy diet can help moisturize skin from the inside out. The key ingredient in most moisturizers is water, so it makes sense that drinking plenty of water will help maintain the body's moisture levels. On the other hand, caffeinated drinks and alcohol should be avoided, as they act as a diuretic and cause the body and skin cells to lose fluids and essential minerals.
A diet rich in vitamins and minerals from vegetables, fruits, grains, seeds and nuts helps to nourish the skin as well as the body. Using cold-pressed oils and avoiding fried foods is recommended.
Including olive oil as part of a healthy diet has merit, but it may be more popular as an ingredient in moisturizers. The ancient Romans were known to bathe in olive oil and used a scraper, called a strigil, to remove the excess [source: VRoma Project]. While bathing in olive oil is not recommended, it can be helpful in small amounts as an occlusive ingredient, or one that slows the evaporation of moisture from the skin, and it's found in many moisturizers and soaps.
Speaking of food, many home moisturizing remedies contain one or more edible ingredients, including eggs, honey, milk, avocado and bananas. However, homemade is not necessarily cost-effective, as these concoctions don't contain preservatives and tend to spoil quickly.
Don't get any ideas if you notice urea, or the organic compound in many mammals' urine, is an ingredient in many moisturizers. It's a common humectant, which pulls moisture from humid air. True, urea is found in every healthy cell of the body, and it's the protein metabolized in urine, but a synthetic version, also known as carbamide, is what's used in a wide variety of products, from fertilizer and animal feed to medicine. [source: Columbia Electronic Encyclopedia]. On the skin, urea cream acts in the same way natural urea does by maintaining its moisture balance and suppleness.
For lots more information on moisturizers and skin care, see the links on the next page.