What is a Glycerite?

Excerpt from my new book Making Tinctures: Determining Formulas, Benefits, Safety, Dosage (hoping to have published by June).

A glycerite is similar to a tincture, except glycerin is the solvent instead of alcohol. Glycerin (also spelled glycerine) is a substance similar to sugar and is present in all natural fats. Thus it tastes sweet. Glycerin is a clear syrupy liquid that has no odor. It is a by-product of soap making. Vegetable glycerin produced from coconut oil is widely used by pharmacies and for making alcohol free herbal tinctures called glycerites.

The main reason to use a glycerite is to avoid the use of alcohol, especially for children and for pets. And due to its natural sweetness, it is easier for children and pets to accept compared to most alcohol based tinctures. In the case of a Milk Thistle Seeds tincture that is used for healing and regenerating the liver, if the reason for liver damage is due to overuse of alcohol (i.e., Cirrhosis of the liver due to alcoholism), a remedy that contains alcohol does not make sense. In this case a Milk Thistle glycerite makes more sense.

When I wrote my previous book Making Tinctures: Beyond the Folk Method, I viewed glycerin, as many herbalists do, as a solvent equivalent to alcohol and treated it as such in making glycerites. However, in the years since that book was published, I have worked more with glycerites, as well as have done more research. As a result, I have discovered that there are many considerations including solubility and preservability which require another look at how to use glycerin in tincture formulas. And another discovery is that pure glycerin is a 95% solvent with 5% water, same as pure grain alcohol. It is 190 proof, not 200. This is because when absolute alcohol (100% alcohol) or pure glycerin is created, they immediately interact with the atmosphere to gain 5% water – thus becoming 95% alcohol or 95% glycerin.

To explain how to use glycerin instead of alcohol in a formula for a tincture requires some understanding of what are the differences in properties between alcohol, water, and glycerin, and how each interacts with specific herbal constituents. If you look at the Table of Solubility which shows the solubility of classes of common botanical constituents in alcohol and in water, the constituents classes that are very soluble in water are generally soluble in glycerin. Glycerin extracts a narrower range of constituents that lie in the mid range between alcohol-soluble and water-soluble.

But it isn’t only a matter of solubility. Glycerin is not as good a preservative as alcohol. Glycerin is bacteriostatic in its action, and alcohol is bactericidal in its action. This means glycerin stops bacteria from reproducing, while not necessarily killing them. Alcohol kills bacteria. Thus glycerin is only mildly antimicrobial and antiviral. To prevent microbial growth, the menstruum would need to have at least 60% glycerin, and some herbalists even say 75%.

In addition the glycerite would need to have an expiration date on its label equal to (or earlier than) the expiration date of the glycerin, since glycerin breaks down over time. Why? If you supply oxygen to an organic compound such as glycerin, which you would do each time you opened the bottle of glycerin to make the menstruum, as well as, each time you opened the finished glycerite bottle, you will promote its oxidation. Once broken down by oxidation, any bacteria can now reproduce.

Also glycerin contains three hydrophilic hydroxyl groups, which are responsible for its solubility in water and its hygroscopic nature. Hygroscopic means absorbing or attracting moisture from the air. In other words, glycerin takes water from the air every time you open the bottle. It results in adding water to the glycerite, effectively reducing the glycerite’s potency.

According to Eric Yarnell in his book Phytochemisry and Pharmacy for Practitioners of Botanical Medicine, there is evidence that glycerin actually impairs absorption of plant constituents, though the degree of interference is likely low.

So where does that leave us? Let’s work through some examples to understand what all this means.

Example: White Willow Bark (Salix alba)

To preserve a tincture, it will have at least 25% alcohol, even if all the constituents to be extracted were water soluble. So let’s consider White Willow Bark (Salix alba) with it’s formula of 1:5 in 25% alcohol. By it’s formula we know that the constituents we need to extract for the tincture are all water soluble. The key constituents according to The Essential Guide to Herbal Safety by Simon Mills and Kerry Bone (2005) are:

Phenolic glycosides (2.5% to 11%, such as salicin and salicin esters), flavonoids and condensed tannins (8% to 20%).

All of these constituents are very water soluble. And all are at least generally glycerin soluble.

To use glycerin instead of alcohol, the 25% would need to be replaced with 60% (or 75%) glycerin. Which means 40% (or 25%) would be water. There might be a very slight (if any) reduction in extraction of the water soluble constituents. But doubt it would be noticeable.

Example: Milk Thistle Seeds (Silybum marianum)

Let’s consider an herb on the other end of the spectrum, Milk Thistle Seeds (Silybum marianum) with it’s formula of 1:3 in 95% alcohol. By it’s formula we know that the constituents we need to extract for the tincture are all alcohol soluble. The key constituents according to Herbal Medicines Third Edition by Joanne Barnes, Linda A Anderson and J David Phillipson (2007) are:

Flavolignans (1.5 – 3% silymarin, a mixture containing approximately 50% silibinin, silichristin and silidianin, as well as silimonin, isosilichristin, isosilibinin, silandrin, silhermin, neosilihermins A and B, 2,3-dehydrosilibinin and tri- to pentamers of silibinin).

Flavonoids (Quercetin, taxifolin and dehydrokaempferol)

Lipids (20-30%. Linoleic acid, oleic acid and palmitic acid)

Sterols (Cholesterol, campesterol and stigmasterol)

Other constituents (Mucilages, sugars, amines and saponins)

Key constituent: silymarin

Since the key constituent is silymarin, the issue of solubility centers on that of flavolignans. Flavolignans are lignans bound to flavonoids. And lignans, according to the Table of Solubility, is insoluble in water and very soluble in alcohol, substantiating the formula completely. Although some potency will be lost using glycerin, we can turn this into a glycerite by replacing the 95% alcohol with 95% glycerin. In other words, all glycerin and no water or alcohol.

Example: Skullcap (Scutellaria lateriflora)

So let’s consider an herb that is in the middle of the spectrum, Skullcap (Scutellaria lateriflora), the herb we looked at previously as an example for solubility. Recall that the formula used by various herbalists were 1:5 in (40 – 60)% alcohol, depending on the herbalist whether the percentage of the solvent was 40%, 45%, 50%, or 60% alcohol. Also remember that the herb had both water soluble and alcohol soluble constituents of which the main active constituents: baicalin and baicalein were a flavonoid glycoside and flavonoid aglycone respectively.

Flavonoid glycosides are generally water and alcohol soluble, while aglycones (free flavonoids) are somewhat insoluble in water, but are totally soluble in alcohol.

To turn a skullcap tincture into a skullcap glycerite, we would replace the alcohol with either 60% glycerin or, as some herbalists would insist, 75% glycerin. The percentage of water would then be 40% or 25%, depending on which percentage of glycerin you used.

So bottom line, glycerites should have at least 60% glycerin (again, some would say 75%) as we saw in the White Willow Bark and Skullcap examples. If the formula has a percentage of alcohol greater than these (60% or 75%), the glycerine would be the same percentage as in the original formula for alcohol, just as we did in the Milk Thistle Seeds example.

Following are some of the practical conclusions from both my research and my experience that define why and how I now apply glycerin to my own practice and that you may find useful.

• Glycerin is VERY MESSY to work with, especially when not diluted well with water, which is ALWAYS the case when working with 60% or higher amounts of glycerin.

• With most of the herbs that I have made into glycerites, I have found that it is very difficult to strain and results in a lot of waste, which increases cost.

• For low alcohol percentage formulas, the glycerite becomes considerably more expensive than the tincture and has much less a shelf life (months instead of years).

• With its lower potency, the dosage for the glycerite has to be increased compared to the tincture that had alcohol (except when it is to be used for children). Thus a bottle of a glycerite does not last as long as the same size tincture bottle.

• Considering the use of glycerites for children, personally there are only a few herbal tinctures I would give. Only two have I made into glycerites – Elecampane Root Glycerite for irritating bronchial cough and Agrimony Glycerite for childhood diarrhea. I made both with 60% glycerin and 40% water and after soaking the appropriate time, strained into 2 oz dropper bottles. I made these in late 2018 with an expiration date of 9/1/2019 on the container of glycerin I had bought. I put that date on the label on each 2 oz dropper bottle. I was happy that some parents needed it. But I still ended up throwing away bottles that were not needed and pouring out what was in the Master bottle after the expiration date. I have not made any since then.

• Another tincture I make for children, I do not make into a glycerite. That tincture – Horsetail – is for childhood incontinence, bed wetting. It is only at 25% alcohol, just what is needed to preserve it. Am I concerned about giving this to children? No, and here’s why. Let’s say (just for an example) a child’s dosage is 1 dropperful (approximately 30 drops). 1 dropperful is equal to 1 ml which equals 0.0338 ounces. So for the Horsetail tincture, the amount of alcohol in a dropperful is 25% of 0.0338 = 0.0085 ounces. 1 teaspoon equals 0.1734735 ounces. 1/16 of a teaspoon equals 0.010842094. So that 25% alcohol in a dropperful is less that 1/16th of a teaspoon. And a 50% alcohol in a dropperful is less that 1/8th of a teaspoon.

• Considering the use of glycerites for healing and regenerating the liver, if the reason for liver damage is due to overuse of alcohol (i.e., Cirrhosis of the liver due to alcoholism), I will continue to make glycerites IF REQUESTED, but the wait time for soaking may be too prohibitive. The yield is very low. I only got a few 2 oz bottles worth out of my last batch. I still have one bottle left. It expires next month. Whether the Milk Thistle glycerite is potent enough to be effective is a big concern. Many herbalists do not think so.

So when all is said and done, I will not be maintaining a supply of glycerites, the main reasons being potency concerns (and thus effectiveness), yield, expiration and cost.

But I will use glycerin sometimes, and suggest you do as well. Let me explain.

Have you had a problem with precipitation in your finished tinctures? This is caused by constituents known as tannins. Tannins form precipitates with polysaccharides and some alkaloids, which is why it is a good idea to shake the tincture bottle before taking a dose. As a 10% solution (meaning 10% of the menstruum), glycerin prevents tannins from precipitating in tinctures. It will also allow more constituents to be extracted without losing potency. So I add glycerin, for example, in my Witch Hazel formula. 1:5 in 40% alcohol 10% Glycerin