Herb Granule FAQ

By Eric Brand

What exactly are “granules?”

Granules are concentrated extracts that are made by decocting raw herbs and then evaporating the water to form a dry powder. The basic process typically starts from whole, uncut herbs, which are first processed with traditional pao zhi techniques and then sliced to maximize their surface area. The herbs are then decocted in water and the resulting decoction is evaporated at a low temperature until a viscous paste is produced. From there, the paste can be dried completely to form a pure extract (calledjin gao fen), or it can be sprayed onto a base of starch to form granules in a single step. The former method is common in mainland China, while the latter method is common in Taiwan.

In China, the pure dried extract is usually packaged into 25 kg drums (for industrial use) or single-dose foil packets (for clinical use). The pure dried extract can also be mixed with dextrin to turn the product from a fine powder to large granule kernels. This is typical for export products that are packaged in 100g bottles, because the addition of dextrin allows the product to achieve a relatively uniform concentration ratio and also prevents clumping.

What are concentration ratios?

Concentration ratios express the relationship between the raw herbs and the finished product. For example, if a product is described as 5:1, this means that one gram of the finished granule powder was made from five grams of raw herbs.

The natural concentration ratio of granule products tends to vary from item to item because some substances naturally have more water-soluble material than others. The concentration ratio of granule products made in Taiwan varies significantly from item to item. The local prescription style in Taiwan is based on a total daily target dose and combinations of whole formulas with single-herb additions; few practitioners in Taiwan use granules based on a mathematical conversion to raw herb dose weights. By contrast, granules in mainland China are nearly always dosed based on their raw herb equivalence. The single-dose foil pack products that are common in mainland China have variable concentration ratios but each foil pack is designed to contain the equivalent amount of a standard daily dose by decoction. When mainland Chinese products are exported in the form of 100g bottles, dextrin is often added to bring most items to a uniform concentration ratio of 5:1.

Practitioners that write a raw herb prescription and dispense granules based on their equivalent raw herb dose weight tend to prefer granules that have consistent concentration ratios because it allows for easy and accurate dosing. However, the vast majority of products on the market vary in terms of their concentration ratios, and precise data on concentration ratios is often removed from the label when products are exported to the U.S. This creates confusion for practitioners that base their granule doses on the raw herb weights that they would normally use in a decoction.

What is the best way to take granules?

There are several different ways to consume granules. In Taiwan and Japan, the most common way to administer granules is to pour the powder directly into one’s mouth and swallow it with a bit of warm water. Fine granule powders made with starch are preferable for this method, because if the granules are too large and concentrated it is unpleasant to take them directly by mouth. Most patients in Taiwan take their granules in three divided doses per day (typically 6 grams per dose). As an alternative to swallowing the powder straight, try mixing the powder into a paste by stirring it into a small amount of warm honey. This makes it less dry and a heaping tablespoon of granule/honey paste can be easily swallowed with a bit of water. The granules made in Taiwan typically contain about 50% starch (±15%), so they tend to produce sediment when dissolved in hot water.

In mainland China and Singapore, granules are usually dissolved in hot water. Patients in mainland China usually combine the contents of a dozen little single-dose foil packs (or a single large foil pack of an OTC prepared formula in granule form) and dissolve them in boiled water. The products that are prominent on the Chinese domestic market tend to be highly concentrated so they are a bit unpleasant to take directly as a powder. However, good quality Chinese granules usually dissolve very well in boiled water and often come out remarkably like a decoction. Simply put about 8-15 grams or so in a cup of boiled water and stir till the powder is dissolved.

What is a typical daily dose of granules? How is dosage determined?

It is common for granules to be given at a dose range of about 10-18 grams per day or so. For severe and acute conditions, 15-25 grams per day can be used. For children, the dosage often ranges from 3-10 grams per day. If the case is mild or the patient is weak, the dosage should be on the low side. If the case is severe or the patient is large and robust, the dosage should be on the high side. As a rule of thumb, multiplying the number of ingredients by 1.5 should give a reasonable total daily dose.

There are two major methods of determining dosage when using granules. One method is to use granules based on their raw herb equivalence. The other method is to use a total daily target dose.

Using granules based on their raw herb equivalence is essentially a mathematical calculation. For example, if using a 5:1 granule extract, each gram of granule product equals five grams of raw herbs in decoction. This method is relatively precise if one is using products with a clearly labeled concentration ratio. However, there is a general consensus that the dosage can be reduced slightly because the granule extraction process is more efficient than a stovetop decoction. Consequently, if 100 grams of raw herbs was indicated for a patient, one could probably use 15-18 grams of 5:1 granules instead of using the full 20 grams (at 5:1) that would be indicated based strictly on mathematical equivalence.

When using a total daily target dose (often around 10-18g/day), individual ingredients are dosed proportionally in relationship to one another. Medicinals that are potent by weight or extreme in nature should be given at low doses, generally 0.3-1.5 grams per day. Medicinals that have a balanced nature and a relatively high standard dose in raw decoctions should be used at higher doses, typically 1-3 grams per day. Items that have a moderate, mid-range dosage in decoctions are often used at a dose of 1-2 grams per day.

What is the shelf life of granules?

Many granule companies perform stability tests to verify that the powder will not clump or degrade when stored at different temperatures and humidity levels. Special containers that simulate different environmental conditions are often used for this purpose. However, only a minority of suppliers have actually done long-term stability testing.

Testing results on the long-term stability of granules in sealed containers indicate that granules have a very long shelf life. Minimal changes have been noted in hundreds of products even after eight to nine years. While many manufacturers use a three-year expiration date on the U.S. market, five-year expiration dates are also common for the exact same products in other markets (such as the E.U.). Expiration dates are rarely based on actual evidence of degradation, and in general the expiration dates used for granules are shorter than necessary to reduce liability and encourage product turnover. From the perspective of efficacy and safety, most granules in sealed bottles can probably last for many years beyond their stated expiration dates.

Highly concentrated loose powders tend to clump together within a year or two after the bottles have been opened, but this tendency to clump varies from item to item. Beyond the variation from herb to herb, manufacturing differences (and the amount of inert excipients) also affect the tendency of granules to clump together once exposed to air. Granules that have clumped together can be a nuisance but their quality is not generally affected in any adverse way.