Natural health products come in different forms based on the methods used to extract the active ingredients from medicinal plants. Here is an overview to help you better understand their labels.
Some supplements are made from dried plants: they come in capsules or tablets. Dried plants are also sold in bulk to be prepared as decoctions or infusions [http://www.protegez-vous.ca/sante-et-alimentation/fleur-hibiscus-antioxydants.html]. As with all supplements, the common name, Latin name and parts of the plant used must be listed on the label. On a bottle of red clover, for example, you can read that each gel capsule contains red clover stems, leaves and blossoms and that its Latin name is Trifolium pratense.
Herbal tinctures are made using a traditional method that involves steeping a plant in a solvent – alcohol, glycerine or sometimes vinegar. The solvent then absorbs the medicinal compounds from the plant, leaving a liquid extract with medicinal properties. A ratio is given to indicate the product’s concentration. A ratio of 1:5, for example, means 1 g or plant in 5 ml of solvent. In other words, a 1:10 tincture is less concentrated than a 1:5 preparation. Tinctures generally contain 45 percent or more of alcohol. Dosage is usually given in drops or millilitres.
Liquid extracts are made by infusing or decocting a plant in huge percolators. These contain water and a variable amount of alcohol (or other solvent), depending on the type of compound being extracted. Liquid extracts have a 1:1 or 1:2 ratio (1 g of plant for 1 or 2 ml of fluid), so are usually more concentrated than tinctures. They also contain less alcohol. Dosage is indicated in millilitres.
A solid extract is a liquid extract that has been dehydrated and reduced to a powder. The ratio – or concentration – indicates the quantity of plant used to make one gram of product. For example, a ratio of 1:50 on a bottle of ginkgo solid extract means that 50 g of ginkgo leaves was used to make one gram. A 1:25 ratio indicates a lower concentration. Dosage is usually given in milligrams.
For some plants, we know exactly which compound accounts for its therapeutic effect and how much of it is required for the extract to be effective. Turmeric, for example, contains active ingredients called curcuminoids. Some supplements guarantee the potency of the product by expressing it as a percentage (e.g. 95 percent). A second example is milk thistle. Its active ingredient is sylimarin, which must be found in a 70 to 80 percent proportion for the product to be effective. In the case of ginkgo biloba, the actives are glucoflavonoids and terpenolactones.
In most cases, the active substance associated with a plant’s therapeutic effect is not known. In such instances, one of the plant’s typical compounds is used to establish a standard to guarantee the extract actually contains the right plant at the right concentration. Hypericin, for example, is the marker compound used for St. John’s Wort. Even though hypericin does not account for the plant’s depression-fighting properties, we know that a product containing 0.3 percent of it generally has enough actives to deliver the desired effect.
Source: Guide pratique des produits de santé naturels, Protégez-Vous, 2011 (In French only)
To learn more:
Grossesse et produits de santé naturels, Protégez-Vous, July 2012 (In French only)
Des produits de santé naturels pour prévenir le rhume et la grippe, Protégez-Vous, November 2011 (In French only)