| |
Olive Leaf Extract – for Viruses & Bacteria
by Belinda Hope-Too, PGDipHSc
Olive Leaf Extract is a very popular herb used for its
anti-viral, anti-bacterial, anti-fungal activity. Most commonly
it is used successfully for preventing and fighting colds
and flu. For a product with such an important therapeutic
use, it would be expected there is suitable data to back
up its efficacy. Olive Leaf is freely available in health
stores and pharmacies, and any self-respecting immune formula
contains it. A search of the medical journals reveals only
a handful of studies using the active constituent Oleuropein
in vitro. Surprisingly, there were no human studies using
supplement or liquid herbal extract. This seems strange,
given the popularity of this herbal product and the success
stories customers report back. Clearly more studies need
to be completed with larger groups of patients so that where
required by health regulations this herb can be backed up
with supporting data. This report is a review of the current
medical data.
Olive Leaf has a long history of use, especially in Mediterranean
countries. The leaves were traditionally brewed as an immunity
tea in the Mediterranean, and it is still used as a broad-spectrum
germ killer1. It was used in the French-Spanish War in 1800’s
to reduce fever – the medical soldiers eventually
stumbled across the benefits of olive leaf as a last resort,
and it allowed the soldiers to get up and fight again since
their fevers had been relieved2.
These days it is used widely as a herbal method of treating
viruses, bacteria, fungi, yeasts, protozoa, parasites, worms
and so on. It is specifically used for any infections, viruses
such as herpes and Epstein Barr, skin diseases, candida,
malaria and colds and flu1. It is generally considered stronger
than any other herb for preventing and treating these conditions
– even stronger than the ever-popular Echinacea. Sales
of Echinacea are dropping as clients who have experienced
the fast results Olive Leaf offers (even for the most dire
flu symptoms) are switching over to this newer, more efficacious
herb.
With such wide-spread use of Olive Leaf, it would be sensible
to investigate its toxicology. In several long term rat
studies using high doses of Olive Leaf extract no toxicity
was found3. It has been suggested that because Olive Leaf
is technically a ‘vegetable’ traditionally brewed
as a tea or as a bitter addition to salad, ingesting it
is safe, with no side effects2. Its bitter element would
be a natural controller to toxic overdose – only a
small amount would be tolerated by a person, so they would
never be able to take too much due to the strong taste.
The only toxicological point to note would be the Die-off
effect, or Herxheimer Reaction. This may occur in some patients
when the microbe is killed and the cell wall is broken down,
because an ‘allergic reaction’ to this broken-down
cell wall is caused in the weakened immune system2. This
action suggests the Olive Leaf is working, but may cause
the patient to feel a little worse for a day or so before
they make a rapid recovery.
The evidence base for Olive Leaf Extract dates back to the
late 1960’s/early 1970’s4-8. The Upjohn Pharmaceutical
Company experimented with Olive Leaf Extract in vitro and
discovered that it inhibited every virus, bacteria, fungus,
yeast, protozoon it was tested against. They ascertained
the active ingredient was calcium elenolate, derived from
oleuropein. It was found to be effective against many viruses,
including coxsackie, parainfluenza 3, herpes, pseudorabies,
vesicular stomatitis, encephalomyocarditis, Newcastle disease,
polio and Sindbis.
Its activity includes critical interference with certain
amino acids required for microbial growth. Olive Leaf extract
inactivates the virus, and prevents shedding, budding or
assembly at the cell membrane. It directly penetrates into
the infected cell to irreversibly inhibit replication, and
neutralises retrovirus’ production of reverse transcriptase
and protease. It also stimulates phagocytosis as an immune
response to germs. Such a potent action was sure to make
Olive Leaf Extract the biggest anti-viral drug available.
However, drug production was halted as it was discovered
that isolating the Calcium elenolate from the Olive Leaf
Extract actually bound to protein in blood plasma which
made it ineffective in humans. This is a prime example of
the effect of herbal medicine when science intervenes. In
nature, the herb exists as a complex of compounds that work
synergistically to give an end result. Science wants to
find which compound is doing the work so it can be isolated
and maximized in strength. However, this does not always
work as the other seemingly useless components in the original
herb are needed for maximum potential.
To get around this problem, calcium elenolate is not encapsulated
and sold as a dietary supplement, but instead the oleuropein
is combined with the whole leaf to allow all active ingredients
to work together for best results9. ProOlive is a trademarked
method of extracting the oleuropein with calcium elenolate
activity that has managed to bypass the plasma binding action2.
This is the leading Olive Leaf extract product on the market
in New Zealand, and customers advocate its efficacy.
In more recent studies using Olive Leaf extract in vitro
or in animal studies, further evidence of its powerful antiviral
and antibacterial activity has been documented. One study
used Olive Leaf extract to test its anti-HIV activity, and
found it successfully prevented HIV infection and replication10.
It inhibited infection and cell to cell transmission, and
also inhibits viral replication. Olive Leaf extract was
shown to have a dose dependent action for HIV – the
stronger the dose the better the antiviral activity, and
interestingly no cytotoxicity was found on uninfected cells10.
This is an important feature of drugs working on viral or
bacterial destruction – targeting only the infection
and leaving the healthy cells. Olive Leaf extract was shown
to reverse many other HIV infection-associated problems
at DNA level10, which will be very useful in helping general
immunity and ‘recovery’ for the HIV sufferer.
No information could be found on any interaction between
Olive Leaf extract and HIV medication. Perhaps it would
be wise to investigate this further before HIV sufferers
start self-prescribing.
Olive leaf extracts have been shown to inhibit or delay
the rate of growth of certain bacteria and microfungi with
its potent antimicrobial activity, but there is no data
suggesting they are used as antimicrobial agents against
pathogenic bacteria in people11. It was tested against bacteria
and fungi in one study, and it killed almost all bacteria
within 3 hours12. This is a very significant finding, especially
since antibiotics are becoming less effective. Even Candida
was killed within 24 hours with a high concentration extract.
E.coli was completely killed with a very low concentration
extract12, which indicates the power of olive leaf. Bisignano
tested olive leaf extract against a number of bacteria and
fungi, including penicillin-susceptible and -resistant strains
of Staphylococcus aureus, and the successful results have
led them to suggest Olive Leaf can be considered a promising
antimicrobial agent for intestinal or respiratory tract
infections in humans11. Delayed growth of Staphylococcus
aureus has also been shown elsewhere with higher doses inhibiting
growth completely in vitro13. Another bacterial study showed
Oleuropein inhibited germination and outgrowth of Bacillus
cereus T spores14.
Less well known beneficial effects of Olive Leaf extract
include protective activity against chromosomal damage in
bone marrow before and after X-ray treatments15, and antihypertensive,
diuretic, anti-atherosclerotic, antioxidant and hypoglycemic
effects were found in a study looking at an insulin-resistant
rat genetic model of hypertension16,17. Significantly improved
tissue injury from long-term streptozotocin treatment has
also been noted – this suggests olive leaf may provide
benefit from diabetic conditions3.
No interactions have been noted for Olive Leaf supplements,
and from the data above, it seems fairly safe - although
no human data has been documented. Because of this, it is
not recommended for pregnant or breast-feeding women since
its effects are unknown. It is safe enough for children
to take, and children’s formulas are available. Olive
Leaf is widely available in supplements everywhere, since
any good immune formula now has Olive Leaf2. There seems
to be a difference in quality of product - properly extracted
products such as ProOlive generally cost more, but they
are meant to bypass the adverse blood protein binding action.
As with most complementary medicines, you do get what you
pay for.
Olive Leaf appears to be a safe herbal supplement that can
be taken daily as a preventative, or taken in a rapid dose
while sick. Patients should be aware of the die-off effect
(which is printed as a warning on most Olive Leaf packets)
so they don’t stop taking it if they assume they are
getting worse. As with any other illness, if symptoms persist
or there is no improvement then visit the doctor. Olive
Leaf should probably not be self-prescribed for serious
illness as drug interactions are not yet established.
Olive Leaf extract certainly seems to be a wonder herb
from the indications of in vitro experiments, as well as
anecdotal evidence from people all over the world using
it with great success. Its wide use and popularity suggest
that large human studies using the supplement form of Olive
Leaf extract should be established to support the anecdotal
evidence. While everyone who has used this herb is aware
of its strong immune support and powerful antiviral and
antibacterial properties, it is reassuring to have scientific
support – especially as new regulations may require
a certain level of science to approve a product for sale.
1. Walker, M. Olive Leaf Extract. Better Nutrition April
(1999).
2. Walker, M. Nature's Antibiotic - Olive Leaf Extract.
(1997).
3. Onderoglu, S., Sozer, S., Erbil, K. M., Ortac, R. &
Lermioglu, F. The evaluation of long-term effects of cinnamon
bark and olive leaf on toxicity induced by streptozotocin
administration to rats. Journal of Pharmacy & Pharmacology.
51, 1305-12 (1999).
4. Elliott, G. A., Buthala, D. A. & DeYoung, E. N. Preliminary
safety studies with calcium elenolate, an antiviral agent.
Antimicrobial Agents & Chemotherapy. 9, 173-6 (1969).
5. Heinze, J. E., Hale, A. H. & Carl, P. L. Specificity
of the antiviral agent calcium elenolate. Antimicrobial
Agents & Chemotherapy. 8, 421-5 (1975).
6. Hirschman, S. Z. Inactivation of DNA polymerases of murine
leukaemia viruses by calcium elenolate. Nature - New Biology.
238, 277-9 (1972).
7. Renis, H. E. Inactivation of myxoviruses by calcium elenolate.
Antimicrobial Agents & Chemotherapy. 8, 194-9 (1975).
8. Renis, H. E. In vitro antiviral activity of calcium elenolate.
Antimicrobial Agents & Chemotherapy. 9, 167-72 (1969).
9. Walker, M. Olive Leaf Extract. Townsend Letter for Doctors
and Patients May (2001).
10. Lee-Huang, S., Zhang, L., Huang, P. L. & Chang,
Y. T. Anti-HIV activity of olive leaf extract (OLE) and
modulation of host cell gene expression by HIV-1 infection
and OLE treatment. Biochemical & Biophysical Research
Communications. 307, 1029-37 (2003).
11. Bisignano, G. et al. On the in-vitro antimicrobial activity
of oleuropein and hydroxytyrosol. Journal of Pharmacy &
Pharmacology. 51, 971-4 (1999).
12. Markin, D., Duek, L. & Berdicevsky, I. In vitro
antimicrobial activity of olive leaves. Mycoses. 46, 132-6
(2003).
13. Tranter, H. S., Tassou, S. C. & Nychas, G. J. The
effect of the olive phenolic compound, oleuropein, on growth
and enterotoxin B production by Staphylococcus aureus. Journal
of Applied Bacteriology. 74, 253-9 (1993).
14. Tassou, C. C., Nychas, G. J. & Board, R. G. Effect
of phenolic compounds and oleuropein on the germination
of Bacillus cereus T spores. Biotechnology & Applied
Biochemistry. 13, 231-7 (1991).
15. Benavente-Garcia, O., Castillo, J., Lorente, J. &
Alcaraz, M. Radioprotective effects in vivo of phenolics
extracted from Olea europaea L. leaves against X-ray-induced
chromosomal damage: comparative study versus several flavonoids
and sulfur-containing compounds. Journal of Medicinal Food.
5, 125-35 (2002).
16. Somova, L., Shode, F., Ramnanan, P. & Nadar, A.
Antihypertensive, antiatherosclerotic and antioxidant activity
of triterpenoids isolated from Olea europaea, subspecies
africana leaves. Journal of Ethnopharmacology 84, 299-305
(2003).
17. Khayyal, M. T. et al. Blood pressure lowering effect
of an olive leaf extract (Olea europaea) in L-NAME induced
hypertension in rats. Arzneimittel-Forschung. 52, 797-802
(2002).
|
