According to Health Canada, an adult can take between 40 mg and 2400 mg of the dried root and rhizome of Black cohosh (Actaea racemosa). When selecting a product you need to verify the amount of Dried Herb Equivalent (DHE) of Black cohosh root and/or rhizome. Many products are made from extracts of Black cohosh and not powdered dried root and/or rhizome. Some of these extracts may be a 4 to 1 (extract ratio 4:1) or 8 to 1 (extract ratio 8:1) extract of the dried root and rhizome. A 4:1 extract is a powder that is 4 times more concentrated than the dried root and rhizome or in the case of an 8:1 extract it would be 8 times more concentrated. Therefore, 50 mg of a 4:1 extract is equivalent to 200 mg of the dried root and rhizome. Some companies may express the latter as 200 mg of the DHE.
Product labels should contain the information required for you to determine the amount of dried root and/or rhizome (i.e., DHE) that each capsule or tablet contains. Some manufacturers may write it very clearly stating the product contains 50 mg of an extract equivalent to 200 mg of the dried root and rhizome of Black cohosh. Others may write 50 mg of a 4:1 extract of the dried root and rhizome. Always look for the amount of an herb, or herb part like the root and/or rhizome, expressed as the DHE. Safety data is usually expressed based on the DHE since extracts vary from company to company.
In the case of a product that is made from the powdered dried root/rhizome, the label would read, for example, 550 mg of Black cohosh dried root. You can safely take 4 capsules per day of the 550 mg Black cohosh dried root product. Taking 4 capsules provides a daily dose of 2200 mg of Black cohosh dried root and this is below the maximal daily intake recommended by Health Canada of 2400 mg.
Response by Guy Chamberland M.Sc., Ph.D.