Andy wrote:
>
> My local NBC morning news reported "from a reliable source"
> http://www.healthday.com/Article.asp?AID=609977 that sodium nitrate and
> sodium nitrite are heart healthy.
>
> Well I don't buy it. Quite possibly the most falsified study ever conducted
> in the history of food science.
>
> They're proven carcinogens since the early 1970s. Certainly not GRAS.

It's not the nitrates and nitrites (nitrates turn into
nitrites), but the N-nitroso compounds they form. Recent
information about the health effects of nitrites used
in cured meat products is showing that what we thought
we knew even 10 years ago was wrong or inaccurate.

Two common beliefs that now require revision a

1) Nitrosamines are the principal health threat from
adding nitrites to meat. Although nitrosamines are
poweful carcinogens, new evidence indicates that
nitrosamides may be the greater danger.

2) Meat must be cooked at high temperature to form
the dangerous N-nitroso compounds (such as nitrosamines).
That's not true at all. Although high temperature
cooking will cause formation of these compounds,
they also form in the intestines from precursors
in cured meats that contain little or no N-nitroso
compounds (a process called "endogenous N-nitrosation").

Relevant to (1):

Cancer Epidemiol Biomarkers Prev. 1996 Aug;5(8):599-605.
Maternal consumption of cured meats and vitamins
in relation to pediatric brain tumors.
Preston-Martin S, Pogoda JM, Mueller BA, Holly EA,
Lijinsky W, Davis RL.
Department of Preventive Medicine, University of
Southern California/Norris Comprehensive
Cancer Center, Los Angeles 90033-0800, USA.

Brain tumors are the leading cause of death from
childhood cancer, yet the causes of most of
these tumors remain obscure. Few chemicals are
effective in causing brain tumors experimentally
after systemic administration of low doses; a
notable exception is one group of N-nitroso
compounds, the nitrosamides (in particular the
nitrosoureas). Feeding pregnant animals
nitrosamide precursors (e.g., sodium nitrite and
an alkylamide such as ethylurea) causes a high
incidence of nervous system tumors in offspring.
This population-based epidemiological study
was designed to test the hypothesis that maternal
consumption during pregnancy of meats cured
with sodium nitrite increases the risk of brain
tumors among offspring. The intake of vitamins C
and E blocks endogenous formation of nitroso
compounds and was expected to be protective.
Mothers of 540 children under age 20 with a
primary brain tumor diagnosed during 1984-1991
and 801 control children in the same 19 counties
on the U.S. West Coast were interviewed. Risk
increased with increasing frequency of eating
processed meats [odds ratio (OR) = 2.1 for eating
at least twice a day compared to not eating; 95%
confidence interval (CI) = 1.3-3.2; P = 0.003).
Risk also increased with increasing average daily
grams of cured meats or mg of nitrite from
cured meats (P for each <0.005) but not with
nitrate from vegetables. Daily use of prenatal
vitamins throughout the pregnancy decreased risk
(OR = 0.54; CI = 0.39-0.75). Risk among
mothers who consumed above the median level of
nitrite from cured meat was greater if vitamins
were not taken (OR = 2.4; CI = 1.4-3.6) than if
they were (OR = 1.3). These effects were
evident for each of three major histological
types and across social classes, age groups, and
geographic areas. This largest study to date of
maternal diet and childhood brain tumors suggests
that exposure during gestation to endogenously
formed nitroso compounds may be associated
with tumor occurrence. Laboratory exploration is
needed to: (a) define dietary sources of
exposure to alkylamides; (b) investigate the
reactivity of nitrite in high concentration such
as around bits of cured meats in the stomach
after ingestion compared to nitrite in dilute
solution; and (c) confirm that simultaneous
ingestion of alkylamides and cured meats leads
to the endogenous formation of nitrosamides.

Cancer Causes Control. 2005 Aug;16(6):619-35.
A review: dietary and endogenously formed N-nitroso
compounds and risk of childhood brain tumors.
Dietrich M, Block G, Pogoda JM, Buffler P,
Hecht S, Preston-Martin S.
School of Public Health, University of
California-Berkeley, Berkeley, CA 94720-7360, USA.

Maternal dietary exposure to N-nitroso compounds
(NOC) or to their precursors during
pregnancy has been associated with risk of
childhood brain tumors. Cured meat is one source of
exposure to dietary NOC and their precursors.
Most epidemiological studies that have examined
the role of maternal consumption of cured meats
during pregnancy have found a significant
positive association between maternal intake
of cured meat and the risk of childhood brain tumor
(CBT). NOC consist of two main groups,
N-nitrosamines and N-nitrosamides. The
carcinogenicity profiles of NOC suggest that
N-nitrosamides rather than N-nitrosamines are the
compounds that may be associated with CBT
and that they should be investigated more closely
in epidemiological studies. We present a review
of the chemical and carcinogenic properties of
NOC in connection with the findings of case-control
studies. This approach may be helpful in
determining the essential information that
must be collected in future epidemiological studies on
CBT.

Relevant to (2):

Nutr Cancer. 2002;42(1):70-7.
Effect of vegetables, tea, and soy on endogenous
N-nitrosation, fecal ammonia, and fecal water
genotoxicity during a high red meat diet in
humans.
Hughes R, Pollock JR, Bingham S.
Dunn Human Nutrition Unit, Medical Research Council,
Cambridge CB2 2XY, UK.

Red meat increases colonic N-nitrosation, and
this may explain the positive epidemiological
relationship between red meat intake and colorectal
cancer risk. Vegetables, tea, and soy have
been shown to block N-nitroso compound (NOC)
formation and are associated with protection
against colorectal cancer. To determine whether
these supplements affect fecal NOC excretion
during consumption of a high red meat (420 g/day)
diet, 11 male volunteers were studied over a
randomized series of 15-day dietary periods. Seven
of these subjects completed a further dietary
period to test the effects of soy (100 g/day).
Soy significantly suppressed fecal apparent total
NOC (ATNC) concentration (P = 0.02), but
supplements of vegetables (400 g/day as 134 g
broccoli, 134 g brussels sprouts, and 134 g petits
pois) and tea extract (3 g/day) did not affect
mean levels of fecal ATNC, nitrogen and ammonia
excretion, and fecal water genotoxicity.
However, fecal weight was increased (P < 0.001)
and associated with reduced transit time (r =
0.594, P < 0.0001), so that contact between ATNC,
nitrite, and ammonia and the large bowel
mucosa would have been reduced. Longer transit
times were associated with elevated fecal
ATNC concentrations (r = 0.42, P = 0.002). Fecal
nitrite was significantly suppressed during the
tea supplement compared with the meat-only
(P = 0.0028) and meat + vegetables diets (P =
0.005 for microgram NO2/g).

Cancer Res. 2003 May 15;63(10):2358-60.
Haem, not protein or inorganic iron, is responsible
for endogenous intestinal N-nitrosation arising
from red meat.
Cross AJ, Pollock JR, Bingham SA.
Medical Research Council, Dunn Human Nutrition Unit,
Wellcome Trust/MRC Building, Cambridge CB2 2XY,
United Kingdom.

Many N-nitroso compounds (NOC) are carcinogens.
In this controlled study of 21 healthy male
volunteers, levels of NOC on a high (420 grams)
red meat diet were significantly greater (P =
0.001) than on a low (60 grams) meat diet but
not significantly greater when an equivalent
amount of vegetable protein was fed. An 8-mg
supplement of haem iron also increased fecal
NOC (P = 0.006) compared with the low meat diet,
but 35-mg ferrous iron had no effect.
Endogenous N-nitrosation, arising from ingestion
of haem but not inorganic iron or protein, may
account for the increased risk associated with
red meat consumption in colorectal cancer.

[Note that haem iron comes from breakdown
products of blood -- the ancient rabbis who
developed the kosher dietary laws may have
been on to something when they required
through removal of blood from meat.]