The term
herbal or plant extract is used a lot in articles, books and catalogues but
what is an extract? Is it the same as the original herb or plant? Or is it
something different?
Extraction is
like the art of making tea.
A solvent is
used to extract elements or compounds from the plant or herb but which the
extractor may call the drug. Each herb or plant contains lots of different
chemicals such as vitamins, minerals or other components. These are called the
actives i.e. the molecules that do the work for which the herb is renowned such
as pain killing or reducing inflammation.
It follows
then that the type of solvent determines the nature of the extract. Different
chemicals in the herb or plant engage with different solvents. There are for
example water soluble components, oil soluble components etc. A variety of solvents may be used each of
which has its own advantage or disadvantage and each of which is poor or better
at extracting a certain component.
Some solvents
have secondary effects e.g. alcohol or propylene glycol which have preservative
properties. Solvents are not necessarily
interchangeable.
The solvent
has a maximum carrying ability. Once saturated
the solvent cannot take up any more of the chemistry of the plant. This is the
best sort of extract. Using the example of tea again you can make weak tea or
strong tea so not all extracts are the same value and this is sometimes
reflected in the price of a product. Weak tea goes further! Many times extracts
are not added for efficacy but rather to make a product look as though it
contains lots of useful items.
As noted
above, an extract can be made whereby the solvent is not saturated but rather
the solvent (relatively cheap) is in effect “tainted” by a plant rather than
being “full” of plant. This is a cheap
way of making extracts whereby only a small or insubstantial volume of plant
material is used. Alternatively, old
material is used or re-used.
These cheap
extracts should not be compared with a standardised extract. Such an extract is where a key component is
certain to be present at a given level.
A common or average is found and the extract adjusted to comply. A common means of measuring the key molecule
or component present is by UV spectroscopy.
This component
or tracer can be further concentrated or filtrated to a reproducible or
measurable componency (also referred to as a standard extract but more
correctly concentrated standard extract).
Purified extracts refer to the highest levels of certain molecules. Perhaps other synergistic molecules are
maintained to increase the activity of the plant drug.
Herbal
specification data mostly mentions the quantity of plant used such as organic
or other status and the dry residue as a point of reference and therefore
standardisation of quality. The quality
of an extract is solely linked to its concentration or containment of active
principles. These can only be measured
through proper analysis.
So not all
extracts are the same in value. Seeing a herbal name on the back of a pack (the
INCI list) tells you little about the real quality or value of an extract, the
good, the bad and the ugly all have the same name. Price becomes some guide as
does the brand name which builds trust with its promotional material. Read the
core values of a brand and its claims which may even tell you the value of the
extracts used.