Should Grapefruit Have a Health Warning
Threads - Should Grapefruit Juice
and Fruit Carry a Health Warning
On 17/3/2003, David Maddern
posted:
We have looked at the toxicity of broccoli, potatoes, etc but here is a
doosy.
I don't know how widely this is known, but it has been known for a
while that Grapefruit juice can interfere with many drug's actions.
Particularly worrying, given the low dose nature of the modern
contraceptive pill, and the grapefruit juice bottle is silent.
I wonder how many 'accidental' pregnancies there have been due to this.
Or for that matter 'unexplained miscarriage' via a drug's activity
being modified.
looking around the site below there is at least one poor child ended up
in Intensive Care
http://www.powernetdesign.com/grapefruit/
Worth taking on board some of the stuff there.
So should it have a mandatory health warning?
Could a supermarket be sued?
Margaret
Ruwoldt replied:
>I
don't know how widely this is known, but it has been known for a
>while that Grapefruit juice can interfere with many drug's actions.
My father's
heart medication is clearly labelled with warnings about not eating
grapefruit or drinking grapefruit juice, and his doctors remind him
regularly about such contra-indications.
I expect there would be similar warnings on other drugs that react
adversely with particular food or other substances (where those adverse
reactions are known and proven).
If there were no warnings of known risks, then the pharmaceutical
companies would be exposed to expensive damages claims. Look at
cigarettes in the US, for example.
I'm not sure what labelling grapefruit would achieve that the current
labelling system does not (or cannot).
Ray added:
There is a name for this kind of phamaceutical reaction between
different substances, whereby one or other substance is totally
harmless on its own but together they're deadly.
I forget this title. Chris? Ian? Anyone?
One of the lesser known of such things is a mushroom called Coprinus
astramentarius, a fairly common 'sroom of Australia's SE. No
problem as a sauce for your steak, as long as no alcohol is consumed
for at least 12 hours with and after ingestion. Add alcohol, and
they could be the last meal you eat.
As everyone ought to know, mushrooms are not to be eaten without good
ID and wisdom. Mushie season begins around Mothers
Day. Fair warning methinks.
Chris
Lawson supplied:
Interaction
is probably the word you're after -- but it applies to all sorts of
reactions, not just deadly ones.
Ray responded:
The word I was looking for isn't interaction Chris, although that would
probably do. The term is phamaceutical. I vaguely recall
there are a number of terms for basic varieties of phamaceutical
interactions in terms of affect and toxicity.
There are those with a direct influence on their own, those which react
with integral body chemistry, and those which react in the presence of
other external chemicals.
I read it somewhere, sometime.....
Peter
Macinnis replied:
> > > There is a name
for this kind of phamaceutical reaction between
> > > different substances, whereby one or other substance is
totally
> > > harmless on its own but together they're deadly.
> > Interaction is probably the word
you're after -- but it applies to all
> > sorts of reactions, not just deadly ones.
> I think there is a technical
toxocological, not medical, term for two-part
> poisons, but I have forgotten what it is. Macinnis may
know...
I
have not, in my recent extensive burrowings in matters toxicological,
seen any precise term, which may mean More Research
Required,
rather than the lack of such a term.
But
Chris, what is wrong with "synergy" or "synergism" here? Mind
you, people are of two minds about the additive nature of poisons. The
emperor Claudius had an edict published, declaring that yew juice is a
sovereign remedy against snake-bite, and in these uncertain times, it
may be worth noting that a cloth soaked in urine is good to breathe
through in the event of a gas attack. Here are a couple of quotes from
the database. The Pliny is in Philemon Holland's translation, and
almost needs a translator, but I think it more fun than
post-Shakespearean versions.
PLINY:
"Howbeit, as deadly a bane as it is, our forefathers have devised means
to use it for good, and even to save the life of man: found they have
by experience, that being given in hot wine, it is a counterpoison
against a sting of scorpions: for of this nature it is, that if it meet
not with some poison or other in men's bodies for to kill, it presently
setteth upon them and soon brings them to their end: But if it
encounter any such, it wrestleth with it alone, as having found within,
a fit match to deal with: neither entereth it into this fight, unless
it find this enemy possessed already of some noble and principal part
of the body; and then it beginneth the combat: a wonderful thing to
observe, that two poisons, both of them deadly of themselves and their
own nature, should die one upon another within the body; and the man by
that means only escape with life."
Modern
medical opinion is different:
ANONYMOUS:
"Modern therapy, particularly of malignancy, makes good use of the
Borgia effect -- two poisons are more efficacious than one." (Collins'
"Medical Quotations" 60.)
Zero Sum wrote:
If my memory has worked sucessfuly over night, the word I was looking
for may have been "syncretic" poisons.
Jim Edwards added:
>From
a longstanding grapefruit juice addict . . .
Is
the word you are looking for "contraindication"?
Ian Musgrave replied:
At 09:03
19/03/03 +1100, Ray wrote:
>It seems that the photocopies required are missing.
>The book however is "Pharmacology" by H.P.Rang & M.M.Dale,
published 1987
>Churchill Livingstone
>ISBN: 0-443-03407-9.
Rang and Dale 4th edition is very good, and is the required text in the
course that I help teach.
>The chapters
I'd need to find (probably in another A4 box) are Chap23 p524
>Interactions with drugs and foods, and all of Chapter 36 (pp
>692-702) Harmful effects of drugs.
Now Chapter 48 Individual Variation and Drug interaction and Chapter 49
Harmful Effects of Drugs.
They are just called drug interactions. There are two basic kinds of
drug interaction; pharmodynamic interactions, where
the drugs (or drugs and foods) interact via the mechanisms of action
and pharmacokinetic where one drug or food alters the
concentration of another.
An example of pharmacodynamic interaction is that of the
anticoagulant warfarin and vitamin K. Warfarin competes with vitamin K
for the binding site on the enzymes that synthesize blood clotting
enzymes such as prothrombin, so that the coagulant enzymes cannot be
synthezied.
An example of pharmacokinetic interaction is that of
grapefruit juice and drugs. Grapefruit juice contains psoralens that
inhibit an enzyme responsible for breaking drugs down (cytochrome P450
variant 3A). This means that drugs are broken down more slowly and
their plasma levels (and hence effects and side effects) are increases.
The exception to this are drugs which need to be
partly broken down to work. Terfanidine is a drug for treating high
blood pressure that need to be converted to carboxyterfanidine by
cytochrome P450 to work. Grape juice prevents the production of the
active drug by inhibiting cytochrome P450, and causes further harm
because high levels of terfanidine can stop the heart beating.
In terms of health warnings. All drugs that are affected by grapefruit
juice (and not all drugs are broken down by the cytochrome P450 variant
3A pathway) have very prominent warnings on them to this effect.
and further, in response to posts by Ray and Peter Macinnis:
> >
Thanks Ian.
> > "pharmacokinetic" it is.
>So what was wrong with
synergy or synergism, then? Would they not be
>acceptable, if slightly less precise, synonyms?
In pharmacology, a synergistic effect of drugs mean that the combined
effect is more than the effect of two drugs separately. An example is
the interaction between the hormones noradrenaline and angiotensin II
on blood vessel contraction. The ability of angiotensin II to contract
blood vessels in the presence of a threshold concentration of
noradrenaline (that doesn't by itself contract the blood vessel) is
many times the effect of angiotensin II itself.
Many cases of pharmacodynamic and pharmacokinetic interactions are not
synergistic, in the pharmacological sense. In the case of Terfanadil
and grapefruit juice, the effect of Terfanadil is exactly that due to
it's plasma concentration, there is no synergism between the grapefruit
juice and the Terfanadil.
Also, we pharmacologists like to have labels that tell us why an
interaction is happening. Synergism doesn't help, whereas
phramacodymaic and pharmacokinetic gives some idea of what is going on.
On
21/5/2003, Jim Edwards posted:
Results
of my Google search. I may print this off and show it to my
doctor.
pravastatin
(PravacholÒ) - Pravachol is the only one of my
medicines which showed up on the Grapefruit juice interaction
site, and it seems to be an exception among the statin type drugs.
Pravastatin,
a HMG-CoA reductase inhibitor and cholesterol-lowering drug, was
studied for a grapefruit juice interaction. Eleven healthy
volunteers received either 200 mL water or DOUBLE-STRENGTH
grapefruit juice three times daily for two days before receiving
a single 40mg dose of pravastatin with either 200 mL water or
grapefruit juice in a randomized crossover fashion. GJ had
no significant effects on the pharmacokinetics of pravastatin, other
than the Tmax of active HMG-CoA reductase inhibitors was
significantly prolonged from 1 hour to 2 hours. 52 Pravastatin is
a hydrophilic HMG-CoA reductase inhibitor with an oral
bioavailability of approximately 20%, and is excreted to a
significant extent unchanged in the urine. CYP3A4 plays
only a minor role in the metabolism of pravastatin, which
explains why pravastatin is not susceptible to interaction with
GJ and other CYP3A4 inhibitors.
Cashew
Nuts
Diet
Nutrition & Cashew Nuts:
Cashew
nuts, like all nuts, are an excellent source of protein and fiber.
They are rich in mono-unsaturated fat which may help protect the
heart. Cashew nuts are also a good source of potassium, B
vitamins and folate. They contain
useful amounts of magnesium, phosphorous, selenium and copper.
Like
peanuts, cashew nuts are often salted. This added sodium content may
contribute to increased blood pressure. So buy plain roasted
cashew nuts without added salt.
Calories
in Cashew Nuts:
1
oz/25g = 160 calories
It
seems that it is salted cashews that are the problem, relating to blood
pressure. No mention of cholesterol.
