Complementary Alternative Cardiovascular Medicine

Chapter 2 / Herbs and Supplements 17
One problem with standardizing extracts is that we often do not know
which chemicals in an herb contribute to its health benefits. Only a few
of the hundreds of herbs on the market are standardized to known active
principles. Examples include kava, senna, ginseng, ephedra, cola, and
maté. Other extracts are standardized to “marker” compounds, which
may not be critical to the plant’s effectiveness. Markers are chosen based
on some evidence that if the extract contains enough of the marker compound,
it will be effective. St. John’s wort is a good example. Its standardized
extracts have well-researched antidepressant effects, despite
that the marker compound to which extracts are standardized, hypericin,
is not the “active principle” in this antidepressant herb (5). However,
clinical trials prove that an extract (made in a certain way) that has
enough hypericin is effective against depression (6). Whichever chemical
or chemicals are responsible for this effect are extracted along with
the hypericin, so the hypericin serves as a good marker.
One of the risks of standardizing extracts to a single chemical compound
is the possibility of an unscrupulous manufacturer boosting the
level of the marker compound with a cheap, synthetic chemical. This is
called “spiking” and is believed to be uncommon for most herbs, partly
because cheap synthetic sources of most marker compounds are not
available. There is sound evidence of spiking in ephedra products (inexpensive
ephedrine is available), but this is a dangerous practice for
manufacturers because it is both unethical and illegal.
A larger problem is that in independent tests, some products have
failed to contain the levels of marker compounds that are stated on the
label. In some cases, no marker compounds were found in these tests,
indicating that the product may not have included any of the labeled
herb. In either case, this could result from either poor quality control or
intentional fraud.
Hydroalcoholic Extracts (Tinctures)
The simplest extracts on the market are hydroalcoholic extracts, sometimes
called tinctures, which are sold in dropper bottles. These are usually
labeled with a ratio that tells you how much of the herb is present in
a given quantity of an extract. The ratio is a measure of the weight of herb
(the first number) used to make a certain amount of extract (the second
number). If 1 kg of herb is extracted to produce 1 kg of extract, the extract
is a “one-to-one,” or 1/1, extract. An extract labeled 1/1 is roughly equivalent
to an equal weight of the herb. One dropperful usually contains
approx 1 mL of extract, which weighs approx 1 g, so 1 dropperful of a
1/1 extract is approximately equal to 1 g of the herb. In a 1/5 extract, 1 g
of herb is present in 5 g (5 mL) of extract. It takes 5 dropperfuls of a 1/5