warning: This is my own review of published literature on the health effects of saccharin. I do not have any formal training in
medicine, and only a smattering in
biology and
neurology (I have a
BA in
psychology). I am fairly certain that I can interpret the research properly, and that I have not drawn any inappropriate conclusions. But this writeup should not be relied upon for medical or other
mission-critical advice.
It appears that
sodium saccharin (the form of saccharin which is used as an
artificial sweetener) uncontestably causes
bladder cancer in
rats (mostly male rats). However, it does not have this effect on
mice,
hamsters and
guinea pigs (Ellwein, L.B. & Cohen, S.M. Crit Rev Toxicol, 1990. 20: 311-326) . It has been suggested that a rat-specific
protein causes an intense susceptability to bladder irritation and
neoplasm formation in response to saccharin. In fact, since similar
tumorigenicity has been observed at equal doses of sodium
ascorbate, sodium
citrate, and table
salt (
sodium chloride), it appears that the Na+ ion is doing more than the saccharin. The high concentration of rat
urine compared to
primate urine probably contributes to this effect.
A recent study at the
National Cancer Institute (Takayama, S. et al.,
Journal of the National Cancer Institute, 1998. 90(1). 19-25), a division of the
National Institutes of Health, fed 20
monkeys 25
mg/kg NaSaccharine/day 5 days/week for 24 years (or until death), starting from birth or 1-2 days after. This is about 10X the recommended safe daily dosage for humans. The authors found no evidence of increased
tumor growth in these monkeys compared to
controls. Several monkeys from both groups also had their urine examined during their last 2 years, and no differences were found, nor were there any deposits of the type correlated with tumor growth in rats.
On this basis, the authors conclude that the rat evidence is misleading and that, barring
epidemiological evidence of increased cancer in
human users, we should judge saccharin safe. However, Jacobson et al. (
Journal of the National Cancer Institute, 1998. 90(12). 934-936) point out several troubling issues:
1) The experiment was not powerful enough. That is, with such a small number of subjects a weak but real and repeatable effect would be indistinguishable from chance. In fact, a there was a
statistically insignificant trend towards greater cancer in saccharin-fed monkeys, leaving the door open for further investigation.
2) While the bladder cancer effect is somewhat rat-specific, it's not as neat as Takayama et al. describe. Both mice and rats show cancers in a variety of other sites in response to high doses (Reuber, M.D.
Environmental Health Perspective, 1978. 25. 173-200.). Takayama et al. claim that these data can be safely ignored, but I haven't tracked down their sources (International Agency for Research on Cancer.
International Agency for Research on Cancer monograph on the evaluation of carcinogenic risks of chemicals to humans. Some non-nutritive sweetening agents. Vol. 22. Lyon, France: IARC. 1980. 118-85 ; Cohen, SM. in
Some species differences in carcinogenesis: thyroid, kidney, and urinary bladder. Lyon, France: IARC. In press (probably published by now).).
3) A large-scale study by the National Cancer Institute (Hoover, R. N. & Strasser, P. H.
Lancet, 1980. 837-840.) found an association between artificial sweetener consumption and cancer in
high-risk male and
low-risk female humans. However, we must note that this lumped all
artificial sweeteners together, including the now-banned
cyclamates.
4) Most serious, in my estimation, is the
conflicts of interest they uncovered. Funding from the
International Life Sciences Institute was acknowledged in the Takayama study. One funder of ILSI is
Cumberland Packing Corporation, a major producer of saccharin. Even worse, one of the authors worked as a paid consultant to the
Calorie Control Council, which is an association of artificial sweetener producers.
5) Despite the fact that the monkeys were given 10X the recommended human dose, in 1977 the 90th
percentile of human users also consumed that much.
So saccharin may or may not be
carcinogenic. I'm not planning to worry about it, since I certainly use less than those monkeys (or those people, who may not deserve cancer but at least deserve no better fate than the people who eat six boxes of
Snackwell's™ cookies). On the other hand, I'm a little more worried about living in America ever since I heard about how saccharin escaped outright illegality in 1977, after the NIH determined that it was too dangerous. They actually did ban its use, but congress overrode them with the
Saccharin Study and Labeling Act of 1977, which kept saccharin legal for a period of 18 months and required the addition of the now-famous warning blurb. 18 months later, they passed a similar act. This carried on until 1997.
groan.
I'm not sure what happened then, but an expert panel at NIH narrowly voted to keep saccharin on the "suspected carcinogen" list and retain the warning. Apparently they no longer feel it needs to be banned outright, though.