Figure this out: calculating herb concentrations
Folk herbalist Jade posed a question about how to calculate exact amounts of each herb in a multi-herb liquid (extract) formula blended in oil, for the purpose of properly labeling the bottles.
Great topic that can be somewhat perplexing, for sure. To answer, I see two separate, but related questions: 1. What’s the resultant herb-equivalent dose of each herb in the oil and 2. What are the proper labeling requirements for commercial products?
Let’s take these one at a time.
First, the dosages, which must again be broken into two parts:
a. Using Jade’s example of using 3 separate herbs, extracting each in a 1:2 ratio, what would be the total amount of each herb if they were equally represented in 1ml of liquid?
In herb-speak, an extract with a “1:2” ratio means that, to have 1g-equivalent of a given herb, you need to take 2ml of the liquid. (Similarly, a 1:3 would mean that you need to take 3mls, 1:4 you take 4mls, and so on.) The lower the second number, the more concentrated the extract because you have to take less liquid to get a given amount of herb.
Now, say you have 3, separate 1:2 extracts. For each one, 2ml of liquid has one g of herb. That means that 1ml of liquid has 1/2g of herb. What if you combine 3 herbs, each in 1:2 extracts, in equal amounts? For simplicity, let’s call this mixture the ‘formula’. Here’s how the math shakes out:
1ml of the formula contains 1/3ml each of the individual extracts.
For each 1/3ml of extract, there is 1/3*1/2g of herb = 1/6g of herb = 0.1666g = 166.6mg
Therefore, for each 1ml of formula, there is 166.6mg-equivalent of each herb in it. (Jade – you nailed it!)
b. Now you’d like to evaporate the liquid off and blend the remaining herb-equivalent with oil: what is the concentration of each herb in the oil?
To answer this you now must decide a new herb:oil ratio as you have a choice as to how much total herb you would like to add per given oil volume. For this example, let’s assume a 1:4 final ratio is desired, and that you ended up with 100ml of extract. From a. above, 100ml extract will have 16.6g herb-equivalent of each herb = ~50g-equivalent left after evaporation.
Thus, to get a 1:4 overall ratio, use 200ml of oil for every 50g-equivalent herb. Note that the ratio for individual herbs will be 1:12 (200/16.6 = ~12). Got it?
Honestly, that was the easy part. The challenging part is navigating all the FDA regulations for labeling ‘Dietary Supplements’. Let’s start with a few References that you should familiarize yourself with. The first is the FDA’s Code of Federal Regulations Title 21, which is the official document governing labeling of Dietary Supplements in the United States.
More readable guides include FDA’s Dietary Supplements Guidance Documents and Regulatory Information, specifically, Chapter IV, Nutrition Labeling. Look for “Other Dietary Ingredients”, which is what herbs fall under since they do not come with a Recommended Daily Allowance (RDA).
In Chapter IV, there are guidelines that specify how to label each individual ingredient – e.g., (fresh/dried) herb (1:X) in Y% ethanol. In terms of total amount of each ingredient (per dose), you may use the guidelines for ‘Proprietary Blend’, which allows you to avoid including specific amounts for each herb. Specifically (paraphrased from Chapter IV, Question 34), list the total weight of all “other dietary ingredients” in the blend. Then list each ingredient in descending order by weight. Use the footnote “Daily Value Not Established”. Review the remainder of this guideline for additional details on labeling.
For your blended oil example, you might like to use ‘Proprietary Blend of XX, YY, and ZZ herbs, infused in oil in a 1:4 (or whatever you choose) ratio.’
Finally, a good way to know if you’re on the right track with labeling is to review other products on the market. Two companies that I value and trust, including with their labeling, include Herb-Pharm, and Herbalist and Alchemist. Shop around their online catalogues and select any herbal formula to view good examples of the labels. Both use the ‘Proprietary Blend’ method.
Food and Drug Administration (FDA), Code of Federal Regulations Title 21 (April 1, 2019)
FDA, Dietary Supplements Guidance Documents and Regulatory Information (April 2005)
American Herbal Products Association (September 17, 2019) Guidance: Federal Labeling Requirements for Herbal Dietary Supplements
Donna Koczaja, M.S., RH(AHG) graduated from Maryland University of Integrative Health (formerly Tai Sophia Institute) with a Master of Science in Therapeutic Herbalism and a Post-Master's Certificate in Clinical Herbalism. She earned Registered Herbalist status from the American Herbalists’ Guild in 2018. Originally educated as a mechanical engineer, she combines the rigor of her original scientific training with the traditional healing art of herbal medicine to partner with her clients to uncover the root cause of their underlying health issues. Also a Master Gardener since 2008, her primary interest is in inspiring others to improve their health and sense of wellbeing through the joys of gardening and the power of natural medicine.
Donna currently practices as the professional herbalist at the MUIH Natural Care Center (410-888-9048x6614) in Laurel, Maryland, and can also do remote consultations from anywhere! Read more about her, what she does, and why she does it at www.greenhavenliving.com, or contact her directly at email@example.com or 240-353-8754.