Carcinogen ratings [was Re: Impact of Caffeine on Health]

Robert Bradbury rbradbur at
Fri Oct 23 13:26:48 EST 1992

People have commented on caffeine and its effects on migraine headaches
and fibrocystic lumps.  Caffeine seems to act by interfering with the p53
anti-oncogene gene.  The p53 gene is a DNA binding protein which seems to
play a key role in delaying cell replication until DNA repair is complete. 
(See B Vogelstein et al: PNAS 1991 252:1708, Cancer Research 1991 51:6304)
Although caffeine may not be a carcinogen itself if it allows cell
replication to occur when damaged DNA is present it will increase
the mutation rate of cells and increase the probability of getting
cancer.  That is the bad news.

Now, if you look at the article by Bruce Ames in the recent issue of
Science (258:261-265) you will discover a ranking of environmental
cancer hazards.  A quick summary using his "human exposure/rodent
potency index" (HERP), a method of comparing hazards using the human exposure
level based on the mutagenicity of the substance in rodent tests is:
	HERP	Daily human exposure	rodent carcinogen
	4.0	wine 250ml		alcohol
	2.8	beer 12oz  		alcohol
	0.4	home air (14hr/day)	formaldehyde
	0.3	lettuce (125 g)		Caffeic acid
	0.1	apple (1)		Caffeic acid
	0.1	Basil (1g dried leaf)	Estragole
	0.07	Brown mustard (5g)	Allyl isothiocyanate
	0.04	Orange juice (6 oz)	d-Limonene
	0.04	Coffee (1 cup)		Caffeic acid
	0.005	Coffee (1 cup)		Furfural
There are a host of other substances in coffee which are carcinogenic
as well but all at very small amounts.  The key thing in all of this
is to realize that there are a large number of substances which are
carcinogenic in our diets and our body seems to defend against them
fairly well, especially if your intake of anti-carcinogenic agents
(Vit C, Vit E, B-carrotene, etc.) is sufficient.  However, only
about 1 in 10 people get eat the recommended amounts of fruits &
vegetables and would obtain recommended levels of these substances
naturally.   A wise person would assume that consumption of substances
which contain harmful chemicals w/o any good chemicals (most alcoholic
beverages, coffee, etc.) should be limited.  This is especially true
of caffeine if at a molecular level it modifies normal gene activity
with regard to DNA repair.

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