To get the maximum benefit from medicinal plants, there are
certain things you need to know.
For example, some plant chemicals — such as curcumin and
quercetin — are poorly absorbed in the gastrointestinal tract.
Others can enter the bloodstream, but cannot get past certain
tissue barriers, such as the protective blood-brain barrier.
Food absorbed from our intestines heads straight to the liver
for detoxification and alteration that makes the chemicals in
the food more useful to the body.
Many chemicals absorbed from our food are actually radically
changed into metabolic products in the liver.
This is not all bad, as studies have shown that often the
metabolic product is even more powerful than the original
compound. This is true for the majority of the plant extracts
called flavonoids and carotenoids — especially the antioxidant
forms and anticancer molecules.
Purity is also a concern with medicinal plants. Many
commercially grown foods are heavily contaminated with
pesticides, herbicides, and fungicides as well as hundreds of
industrial products floating around in the atmosphere.
Like the chemicals in foods, they are detoxified in the liver,
and some of these chemicals are altered to form new, powerful
cancer-causing chemicals.
For example, some pesticides are changed by the liver from a
mild cancer-causing chemical into very powerful cancer causers.
We also see this phenomenon with certain drugs.
For example, acetaminophen is converted to a very toxic compound
that can destroy the liver and kidneys. In this form, it also
severely depletes one of the cell’s most important protective
molecules — glutathione.
In fact, this commonly used drug is the leading cause of liver
destruction, increasing the necessity for liver transplants even
when it is used in recommended doses.
The good news is that naturally occurring compounds in plants
actually impair the system in the liver responsible for
converting acetaminophen into that destructive chemical.
That is, the plant flavonoids and other compounds prevent the
drug from becoming poisonous.
Grapefruit contains such a protective chemical, which is called
naringenin. Therefore, eating grapefruit can reduce the damage
done by acetaminophen.
Grape flavonoids (myricetin and quercetin) have a similar
effect, and other flavonoids in foods can prevent many weak
carcinogens in the environment from being converted into more
powerful carcinogens.
The liver’s detoxification system consists of a series of
enzymes within two major cleansing systems — called phase 1 and
phase 2. Natural plant compounds tend to suppress the phase 1
system and stimulate phase 2, which is the best way to prevent
weak environmental carcinogens from being converted to strong
ones.
The most powerful protection from toxic chemicals happens in the
phase 2 system. Many flavonoids and some vitamins stimulate the
phase 2 system, making it more efficient.
Meanwhile, some plant compounds, such as naringenin, are such
powerful inhibitors of phase 1 detoxification that they can
interfere with the metabolism of prescription drugs and even
caffeine.
Eating a lot of grapefruit can extend the effects of caffeine by
several hours.