This page last updated: June 6,
Should I Add Red Dye to My Hummingbird
Here's my full answer,
with helpful insights from Lanny Chambers & Sheri
Should I add red dye to my
In a word (or two): Absolutely not.
Red dye is a touchy subject for many folks. Some
loathe its use. A few swear by it. The more research I do on this subject, the
more convinced I become that it should NOT be part of a hummingbird's
On May 19, 2005, I went to GOOGLE and did a search
for "hummingbird nectar red dye" and came up with about 5340 hits. I scanned
the first 100 websites and found that the sites that came the closest to
promoting use of red dye in nectars were (surprise), the websites of the
commercial nectar suppliers themselves (read
and the very misleading statement on the subject by Opus at:
The rest, without exception, came out on the side of NOT including red dye in
hummingbird nectar -- many websites emotionally urge readers to NOT include
dyes in the solution, while others warn that it may be harmful and is at least
So why is red dyed nectar still commercially
available? Certain popular hummingbird product companies (Perky Pet, Opus/Gardensong, Duncraft, and
Artline/Briggs, to name a few) insist on offering red-dyed nectar to
consumers. I think they do this, frankly, because through their marketing
scheme they've trained people to expect it that way. It represents big bucks in
Industry leader Perky Pet is representative of the
other suppliers in standing by their decision to offer red nectar, claiming
that they know of no research which proves red dye is harmful to hummingbirds.
True. No formal studies have been published on the
effects of red dye specifically on hummingbirds.
But as hummingbird expert Lanny Chambers points out
in his excellent discussion of this topic, Perky Pet has an ethical obligation
as the industry leader in hummingbird products to do no harm to birds. Their
apparent disregard for strong evidence (see below) about the potential
dangers of these dyes on other small animals concerns me.
By the way,
Lanny's comments are
required reading, too [www.hummingbirds.net/dye.html].
In May 2004, an email to me from Julie McKinney at
Perky Pet's customer service stated that
their dye is "#40 and is FDA approved for all foods." That's a
very misleading statement since FDA approves foods for humans, not animals. And
what's good for humans is not necessarily good for animals. Consider
acetaminophen (Tylenol). It has beneficial effects in most humans, but it "can
cause bone marrow depression, anemia, gastric lesions, and death"
if given to a
Addendum: In follow-up correspondence with Julie at Perky Pet, she
stated that they were working on an "all-natural dye that should be ready later
this summer." Aside from the fact that any additive to hummingbird
nectar is a waste, we'll have to see what "all-natural" actually turns out to
FOLLOW-UP -- Hummingbird aficionados began noticing this new
"natural nectar" product by Perky Pet in early 2005. The label claims that the
"natural red color sourced from a unique blend of flower petals and insects."
Pet's interest in trying to create a product that would be better for hummers
than any of the artificial products on the market (from
Newfield's review) is cheapened by
their statement that they have no plans to phase out
their original, potentially harmful Red #40-containing dyed nectar (per
email May 2005 to Sheri Williamson by PP customer service rep "Jeanine").
In May 2004 an unidentified customer service
representative from Opus emailed me that
"all Opus products have been thoroughly researched and are completely safe
for birds to eat. We use .02096 of 1% red dye #40."
I asked for clarification about the "thorough
research" and "completely safe" and they chose not to respond. To my knowledge,
there is absolutely no published, peer-reviewed research that states that red
dye is "completely safe" for any animal, not to mention hummingbirds. On the
contrary, several published scientific papers suggest just the opposite (see
Opus further justifies their decision to add red dye
by claiming that customers like the ability to see the level of the solution in
the feeder at a glance, something that is a bit more difficult with a clear
On the other hand, one reason NOT to use red dye is
that it masks the presence of fermentation -- it's more difficult to see when
the solution becomes cloudy and starts to spoil. Hence, folks may be more
likely to "extend" the life of their solution beyond the safety zone just
because the red stuff doesn't look as dirty. You be the judge on what's in the
best interest of the birds.
Either of the two red azo dyes, those derived from
coal tar, currently in use in the USA (Red #3 and #40) are problematic, and
many store-bought "food coloring" dyes that some folks add to their homemade
nectar contain a mixture of both.
most widely used red
dye in the USA is FD&C Red #40 [a.k.a. Allura red AC, a.k.a, Red-40, a.k.a.
E129, a.k.a. dialuminum salt of
6-hydroxy-5-(2-methoxy-5-methyl-4-sulfnphenyl) azo-2-naphthalene sulfonic
acid]. It can and does cause
reactions in some humans, especially those sensitive to aspirin.
Red #40 is banned in Denmark, Belgium, France,
Germany, Switzerland, Sweden, Austria and Norway but can be used in the
(the Lethal Dose for 50% of the lab animals) for oral administration in rats is
> 10 g/kg.
A similar red dye, Red #3, is
banned in Norway. "Provisional uses" for FD&C Red #3 [a.k.a. erythrosine, a.k.a. E127...] have
been terminated by the United States Food and Drug Administration, and
listing status of this dye is under review. Until the lengthy and
apparently cumbersome review process is complete, this dye is still legally
available in the USA. The fact that hummingbird nectar suppliers now appear to
make a point that their dye is "Red #40" perhaps reflects the growing awareness
about the dangers of Red #3.
Regarding dye and hummingbirds -- let me point out a
- Some hummingbird enthusiasts claim that in
side-by-side tests, hummingbirds actually prefer the CLEAR solution over an
identical solution which contains colored dyes -- EVEN THE NEW "NATURAL DYE"
BY PERKY PET (Read the initial review
by Nancy Newfield).
- Hummingbirds are attracted to the color of the
FLOWER, not the color of the nectar! Most hummingbird feeders already have
ample splashes of red on them to attract the birds; colored nectar is
- Hummingbird expert Lanny
Chambers cites anecdotal evidence from wildlife rehabilitators who believe
red dyes in hummingbird nectar are responsible for tumors seen in hummingbirds
which feed heavily on dye-laden nectars and are brought to these folks for
- The Accepted Daily Intake (ADI) for Red #40
approved for human consumption by the
Organization (WHO) is a maximum of 7 mg per kg (0.007 mg/g) of body weight
(equivalent to 0.007 mg per g body weight). In other words, a 3.5 gram
hummingbird that consumed 0.0245 mg of red dye would exceed the WHO standards
for humans -- see point # 5-1 below!
- Research by Tsuda, et. al (2001; see below) found
that Red #40 induced statistically significant DNA damage in the colon of mice
when they were given concentrations as low as 10 mg/kg. A 3.5 gram hummingbird
that consumed 0.035 mg of red dye (10 mg/kg) would exceed the concentration
shown to cause DNA damage in mice. Do hummers consume that much? YES! Read
- Research by hummingbird researcher Dave Patton
(unpublished data) showed that a banded and uniquely color-marked Rufous
Hummingbird consumed an average of approximately 10 g of nectar from the same
feeder each day. Using the dye concentration reported by Opus (above;
0.02096 of 1%, a chemist tells us that equals 0.2096 mg of dye per g of dry
mix), and assuming folks mix the recommended 1:4 ratio of dry mix to water by
weight, then 1 gram of Opus solution contains 0.04192 mg of red dye.
Therefore, an average 3.5 gram hummingbird consuming 10
grams of Opus' solution daily would be ingesting about 0.42 mg of red dye daily
(equal to 0.12 mg/g body weight). Remember, the WHO suggests a daily limit
in humans of 0.007 mg/g, and DNA damage was noticed in mice beginning as low as
In simple terms...
The amount of red dye consumed daily by an average hummingbird feeding on Opus
nectar with the dye concentrations supplied above is 17x higher than the
Accepted Daily Intake recommended by the World Health Organization for humans,
and 12x higher than the concentration found to induce DNA damage in
mice. Does this mean it's potentially dangerous for hummers? You
- Red dye has not been scientifically shown to be
harmful to hummingbirds because no such research has been done, directly, on
hummingbirds. Until a researcher puts a bunch of hummingbirds in a lab and
subjects them to terminal experiments, we'll never know for sure. In the
meantime it seems prudent to take information from nectar consumption in
hummingbirds and combine it with information from red dye research done on
other living organisms. That's how World Health Organization gets their
recommendations for consumption limits by humans -- they use research done on
other animals to reach conclusions about how much Red #40 humans should ingest.
The same type of analysis of animal research results suggest that extreme
caution may be warranted regarding using red dye in our hummer feeders.
My conclusion -- by all means, leave it
There is actually published evidence that Red #3
and Red #40 has deleterious effects in some animals. As we've stated
earlier, none of these researchers have studied hummingbirds, but their
conclusions on other animals still are cause for concern. For starters read the
following published research abstracts or summaries (emphasis in RED
are my own):
- Published in 2002: "We determined the
genotoxicity of 39 chemicals currently in use as food additives. They fell into
six categories-dyes, color fixatives and preservatives, preservatives,
antioxidants, fungicides, and sweeteners. We tested groups of four male ddY
mice once orally with each additive at up to 0.5xLD(50) or the limit dose
(2000mg/kg) and performed the comet assay on the glandular stomach, colon,
liver, kidney, urinary bladder, lung, brain, and bone marrow 3 and 24 h after
treatment. Of all the additives, dyes were the most
genotoxic. Amaranth, Allura Red,
New Coccine, Tartrazine, Erythrosine,
Phloxine, and Rose Bengal induced dose-related DNA
damage in the glandular stomach, colon, and/or urinary bladder. All seven dyes
induced DNA damage in the gastrointestinal organs at a low dose (10 or
100mg/kg). Among them, Amaranth, Allura Red, New Coccine, and Tartrazine
induced DNA damage in the colon at close to the acceptable daily intakes
(ADIs). -- Sasaki YF, Kawaguchi S, Kamaya A,
Ohshita M, Kabasawa K, Iwama K, Taniguchi K, Tsuda S. 2002. The comet assay
with 8 mouse organs: results with 39 currently used food additives. Mutat
- Published in 2001: "We determined the
genotoxicity of synthetic red tar dyes currently used as food color additives
in many countries, including Japan. For the preliminary assessment, we treated
groups of 4 pregnant mice (gestational day 11) once orally at the limit dose
(2000 mg/kg) of amaranth (food red No. 2), allura red
(food red No. 40), or acid red (food red No. 106), and we sampled
brain, lung, liver, kidney, glandular stomach, colon, urinary bladder, and
embryo 3, 6, and 24 h after treatment. We used the comet (alkaline single cell
gel electrophoresis) assay to measure DNA damage. The
assay was positive in the colon 3 h after the administration of
amaranth and allura red and
weakly positive in the lung 6 h after the administration of amaranth. Acid red
did not induce DNA damage in any sample at any sampling time. None of the dyes
damaged DNA in other organs or the embryo. We then tested male mice with
amaranth, allura red, and a related color additive, new coccine (food red No.
18). The 3 dyes induced DNA damage in the colon
starting at 10 mg/kg. Twenty ml/kg of soaking liquid from commercial
red ginger pickles, which contained 6.5 mg/10 ml of new coccine, induced DNA
damage in colon, glandular stomach, and bladder. The potencies were compared to
those of other rodent carcinogens. The rodent hepatocarcinogen
p-dimethylaminoazobenzene induced colon DNA damage at 1 mg/kg, whereas it
damaged liver DNA only at 500 mg/kg. Although 1 mg/kg of N-nitrosodimethylamine
induced DNA damage in liver and bladder, it did not induce colon DNA damage.
N-nitrosodiethylamine at 14 mg/kg did not induce DNA damage in any organs
examined. Because the 3 azo additives we examined
induced colon DNA damage at a very low dose, more extensive assessment of azo
additives is warranted." -- Tsuda, S., M.
Murakami, N. Matsusaka, K. Kano, K. Taniguchi, and Y.F. Sasaki. 2001. DNA
Damage Induced by Red Food Dyes Orally Administered to Pregnant and Male Mice.
Toxicological Sciences 61:92-99 [The full PDF of the article
can be read
- Published in 2001: "Erythrosine was given in the diet to provide
levels of 0 (control), 0.005, 0.015 and 0.045% from 5 weeks of age of the F(0)
generation to 9 weeks of age of the F(1) generation in mice, and selected
reproductive and neurobehavioral parameters were measured.
In movement activities of exploratory behaviour,
several parameters were significantly changed in the high dose group, and those
effects were dose-related in adult females in the F(0) and F(1) generations and
in male offspring in the F(1) generation." --
Tanaka, T. 2001. Reproductive and neurobehavioral toxicity study of erythrosine
(Red 3) administered to mice in the diet. Food Chem Toxicol.
- Published in 1997: "Exposure to pesticides,
dyes, and pollutants that mimic the growth promoting effects of estrogen may
cause breast cancer...Red No. 3 increased binding of the ER from MCF-7 cells to
the estrogen responsive element. Consumption of Red
No. 3, which has estrogen-like growth stimulatory properties and may be
genotoxic, could be a significant risk factor in human breast
carcinogenesis." -- Dees, C., M. Askari, S.
Garrett, K. Gehrs, D. Henley, and C.M. Ardies. 1997. Estrogenic and DNA damage:
Red No. 3 in human breast cancer cells. Environ Health Perspect
- Published in 1997: "... The potential
adverse effects of erythrosine (ER, FD & C Red No. 3) on the
spermatogenesis process were investigated in adult mice. ... sperm count as
well as the percentage of motile sperms were significantly inhibited by about
50% and 57% respectively. Moreover, ER was shown to disrupt the normal
morphology of the sperm head. ...it increased the incidence of sperms with
abnormal head by about 57% and 65% respectively. The induced increase in sperm
abnormalities could enhance the spermatogenic dysfunction and germ cell
mutagenicity. These findings indicate that ER in the
used doses has a potential toxic effect on spermatogenesis in mice and in turn,
it may affect its testicular function and reproductive performance."
-- Abdel Aziz, A.H., S.A. Shouman, A.S. Attia, and S.F.
Saad. 1997. A study on the reproductive toxicity of erythrosine in male mice.
Pharmacol Res 35:457-62
- Published in 1994: "The color additive,
Allura Red AC, was given in the diet to provide levels of 0.42, 0.84, and 1.68%
(control, 0%), from 5 weeks of age of the F0 generation to 9 weeks of age of
the F1 generation in mice, and selected reproductive and neurobehavioral
parameters were measured. There were few adverse effects of Allura Red AC on
either litter size or weight, and ratio of male to female was significantly
reduced in the lowest dosed group. Average body weight of offspring during the
lactation period was significantly increased in the lower dosed groups of each
sex. As regards the neurobehavioral parameters, no adverse effect was observed
in the behavioral development during lactation period. There were few adverse
effects of Allura Red AC on either movement activity or maze learning in F1
generation mice, compared with controls in each sex. The dose levels of Allura Red AC in the present study
(approximately 86-1430 times greater than human ADI) produced few adverse
effects in reproductive and neurobehavioral parameters in mice."
Tanaka, T. 1994. Reproductive and neurobehavioral effects
of Allura Red AC administered to mice in the diet. Toxicology
[That Allura Red lacked reproductive and
neurobehavioral effects in this study does not diminish the significance of
other adverse reactions detailed in subsequent research]
- Published in 1990: "A structure-activity
study of 1-amino-2-naphthol derived azo dyes using CASE, the Computer Automated
Structure Evaluation system, revealed that for optimal mutagenicity, reduction
of the azo bond was required, thus suggesting that activity could be related to
the liberated aromatic amines. Although it has long been known that sulfonation
of azo dyes resulted in decreased carcinogenicity and mutagenicity, the present
study elucidates the sites of sulfonation which will decrease mutagenicity
maximally. Comparison of CASE predictions with available mutagenicity data
indicates a concordance. Unexpectedly, CASE indicates
that one of the aromatic amines obtained upon azo reduction of FD and C Red no.
40 is predicted to be mutagenic."
-- Rosenkranz, H.S., and G. Klopman. 1990.
Structural basis of the mutagenicity of 1-amino-2-naphthol-based azo dyes.
- Published in 1983: "Adult Sprague-Dawley
rats were fed diets containing FD and C red dye No. 40 for 2 weeks and were
then bred. The diets were continued for the females throughout gestation and
lactation and were provided continuously to their offspring thereafter. The
treatment groups were: FD and C red dye No. 40 as 0.0, 2.5, 5.0 or 10.0% of the
diet, and a positive control group treated with the toxin hydroxyurea on days
2-10 of life with 50 mg/kg/day given s.c. as a positive control group. Parental
animals were evaluated for weight and food consumption, and females for
reproductive success. The offspring were assessed on a series of tests using
the Cincinnati Psychoteratogenicity Screening Test Battery. Additional measures
were weight, food consumption, physical landmarks of development, and brain
weight. Red-40 significantly reduced reproductive
success, parental and offspring weight, brain weight, survival, and female
vaginal patency development. Behaviorally, R40 produced substantially decreased
running wheel activity, and slightly increased postweaning open-field rearing
activity. Overall, R40 produced evidence of both physical and behavioral
toxicity in developing rats at doses of up to 10% of the diet."
-- Vorhees, C.V., R.E. Butcher, R.L. Brunner, V. Wootten,
and T.J. Sobotka. 1983. Developmental toxicity and psychotoxicity of FD and C
red dye No. 40 (allura red AC) in rats. Toxicology
- Published in 1981: "Unexpected findings in
a mouse study in which the safety of FD&C No. 40 (Red 40) was examined led
to additional experimentation and to new statistical analyses and models. The
possibility of acceleration of tumors raised questions about an operational
definition of acceleration and of appropriate statistical methods for assessing
acceleration, especially in the face of data dredging. The evaluation of Red 40
was further complicated by cage and litter effects and the multigenerational
design. In this report the investigations of these studies are reviewed and are
used to illustrate how new scientific work can emerge through the regulatory
process. A number of issues in animal experimentation that need to be examined
are indicated." -- Lagakos S, Mosteller F. 1981. A case
study of statistics in the regulatory process: the FD&C Red No. 40
experiments. J Natl Cancer Inst 66:197-212
There are also unpublished / unconfirmed aspects of
azo-dyes that trouble some people:
- Several internet sites state that the National
Cancer Institute has reported that p-credine, a chemical used in preparation of
Red #40, is carcinogenic in animals. I've been unable to find direct
confirmation, source, or cited publication for this claim.
- Red-40 has been implicated anecdotally in
and physical ailments, especially in
fairness, I've been unable to find any published studies to support this, and
while my wife (a pediatrician) hears this belief from the parents of some of
her patient's, she remains unconvinced. While some humans do apparently have
sometimes severe "allergic" reaction to azo-dyes, the FDA states on it's
Q & A web page:
"...well-controlled studies... have produced no evidence that food color
additives cause hyperactivity or learning disabilities in children. A Consensus
Development Panel of the National Institutes of Health concluded in 1982 that
there was no scientific evidence to support the claim that colorings or other
food additives cause hyperactivity."
Again, whether or not this dye is "proven" harmful
to hummingbirds there is enough evidence to convince most people that the
potential for it to be harmful outweighs any need to include it in your
solution! It is also at the very least entirely unnecessary. I
encourage you to leave it out of your hummingbird nectar.
If you insist on spending the
extra bucks to buy pre-packaged, commercially available nectar, at least go for
the clear, dye-free stuff. Most companies offer it now, perhaps recognizing the
rising tide of knowledgeable and concerned hummingbird enthusiasts out there. I
recommend the "Best-1" brand -- their company policy has been to
never include red dye in their powdered mixture -- a stand I find
insightful and courageous, especially since it goes against the policy of the
current industry leaders.
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