Health-related products from natural sources.
Text is extract from the Final report of the COST Strategic Workshop on Health and the Natural Outdoors. 2007. Edited by Nilsson, K., Baines, C. & Konijnendijk, C.C. 
The whole report (pdf)
"Plants, including trees, have traditionally been used by conventional and alternative medicine as a source of many different pharmaceuticals, as well as a source of other chemical products. However, there is a great scope for using more advanced techniques in order to identify and extract a greater range of natural products beneficial to health.
Trees, besides timber, produce large quantities of wood residues, foliage, twigs, and bark produced during harvesting and manufacturing. Trees have through evolution developed unique chemical defence systems based on advanced functional molecules. Thus trees are exceptionally rich in bioactive, protective substances. Bioactive compounds found in trees include flavonoids, lignans, stilbenes, terpenoids, phytosterols, fatty acids and vitamins which are known to exert many beneficial effects, for example, antioxidant, anticarcinogenic, and estrogenic effects.
Some bioactive compounds can be used as nutraceuticals, that is, a combination of nutrition and pharmaceuticals. These can contribute to public health as ingredients in dietary supplements and health-promoting (‘functional’) foods and as pharmaceuticals. In fact, such forest-derived health products have already been developed and marketed at a commercial scale. Xylitol products, for example, promote dental health, while sitosterol products lower cholesterol levels and consequently prevent cardiovascular diseases. Pycnogenol is the trade name for an extract from the bark of the maritime pine growing in France. It is a powerful antioxidant and its impacts on cardiovascular health, skincare, diabetes and inflammations, among others, are studied. In 2006 a new lignan product came on the dietary supplement market. The HMR lignan is extracted from knots (branch ‘roots’) in spruce trees and can inhibit the development and growth of hormone-related cancer forms (breast, prostate and colon cancers). It is also a strong antioxidant with estrogenic properties. These three products are extracted from process waste streams in the forest industry and are thus contributing to a more efficient use of natural resources.
Although especially forests represent large natural pharmacies by virtue of their enormous source of tree and plant material with known or potential medicinal or nutritional value, more research is still needed to identify and develop the best applications and products. Nutritional supplements and functional foods are currently of high research interest and are recognised internationally as potential health-promoting agents if consumed on a regular basis and at effective levels. The polyphenols which are particularly abundant in knots and bark have potential not only as health-promoting substances but also as technical antioxidants and biocides. There is also potential in using natural, traditionally known extracts from trees as health-promoting products offered locally by enterprises in rural areas. Examples of such products are pine bark as an ingredient in bread and birch sap as a drink or syrup."