Red Dye No. 40 Kills Celery?

A Facebook scaremongering image and post has been making the rounds since 2017, purportedly showing that if you place a stalk of celery into a vase with red dye no. 40 dissolved in water, it kills the celery. On the other hand, the celery stalks placed in green and blue dye seem quite healthy. These posts claim that this celery food dye experiment confirms the long-held belief that red dye no. 40 is toxic and can cause health problems as well as behavioral problems, such as ADHD, in children. In this article, I will debunk the image and the claim connected to it.

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The original post claims the experiment below was done by a 4-year-old. This is likely true as placing celery stalks into food coloring solutions is very common. The purpose of the experiment is to demonstrate the capillary action of the plant and how the stalks will take up the coloring.

The Common Celery and Food Coloring Experiment

Many images of this experiment are available on the net and a casual viewing will show a problem. Although some such experiments are more successful than others, in most such experiments, the red coloring is taken up by the celery just as the other colors are taken up, becoming most visible in the leaves.

Although the other stalks may seem to have a healthier ‘green’ color, this is most likely because they have taken up green or blue colors.

Red or Not Red?

Some commenters have presumed that the color of the pale and dead-looking celery is due to it having taken up the red coloring. While it does appear that a small amount of red may have been taken up, it does not appear that this is the cause of the overall poor appearance of the celery.

If the celery starts green, and you add red, and the celery ends up looking a bit yellow, does that make sense? This is a favorite explanation and it does seem to make sense. Therefore, the resulting color should not be a surprise. However, in successful experiments, the red color in the celery is quite obvious. Yet, in this one photo, it is not. It seems that something else is at work here. You can’t prove an effect with one experiment or even several. You need many samples.

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Not to be discouraged by logic, health gurus and food-fear mongers have used this image to sew fear among the public and, of course, to help sell their own supplements or ‘natural’ food products. The original assumptions made in the post bear further scrutiny.

Not Red Dye No. 40?

The original poster named ‘red 40’ specifically. It is almost certain that the child who made this experiment did not purchase red dye no. 40. It is almost certainly the case that the child used store-bought food coloring, which typically comes in blue, green, and red.

Based on this, we cannot assume that the red color comes from red 40 exclusively or at all. The leading brand, McCormick, uses a combination of red 40 and red 3 in their red color. If this is a mixture, we cannot, based on these results, rule out red 3 as a culprit.

This is all assuming that there is a culprit. Again, previous experiments have shown that red coloring is taken up by celery and the color can be seen in the celery It is likely that all of these experiments used red 40 as it is a common ingredient in commercial preparations. So, what killed the celery?

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Basic Mistake in Preparation?

One explanation seems most credible. If you want to keep celery fresh by placing it in water, you need to remove it from the root and cut off the bottom, similar to how you would trim the stem of a flower before placing it in water. This allows the plant to more easily take up water.

If the cut end is allowed to dry out before placing it in water, it will not take up water well. Therefore, the simple explanation is that the stalk placed in the red-colored water had an ‘old end’ that did not allow the plant to take up water into its cells. The school-kid who did this celery food dye experiment was not setting out to prove anything about the toxic effects of red no. 40. He or she was simply using a common experiment to demonstrate how celery can take up moisture into its cells. The food dye lets us see this is happening and that is the only purpose of using it.

What Does This ‘Experiment’ Prove?

In reality, this experiment would prove nothing about the danger of red 40 to humans, as we are not celery. The fact is, though, that this result is an outlier. For experimental results to hold water (sorry), these results must be repeatable.

Since this common grade school experiment has been repeated many times without resulting in the death of a celery stalk, these results are questionable, at best. Since other explanations are possible, we can safely disregard the far-fetched claim that red 40 kills celery and therefore must be doing awful things to our body.

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Is this a Hoax?

It would appear that red dye no. 40 is becoming even more harmful to celery! Since this supposed ill effect has become popular (and judging by the traffic to this article, it is immensely popular), more and more images of this red dye celery experiment have been posted online.

As the weeks go by, the ‘effect’ of the red dye on the celery seems to become more pronounced with the celery looking more and more shriveled and dead.

While I do not believe that the original posts were a hoax, I am suspicious that people have now started to purposely place old, shriveled, and yellowed celery into red dye, and placed this next to healthy celery in blue, green, and other colors. Why do this? To get a few hits on TikTok, their website, etc. This neither disproves nor proves the effect, it is simply the nature of the internet, and should not concern us.

How Much Red Dye No. 40 is Safe for Humans?

Since we are not celery, there is no use in considering the ‘dose’ of dye the celery is receiving. For humans, the Acceptable Daily Intake (ADI) for Red Dye 40 is 3.2 mg per pound (7 mg per kg) of body weight. That is just about 476 mg for a 150-pound (68-kg) person.

According to one study, the average American consumes about 0.004 mg Red Dye No. 40 per kg of body weight per day, while another study suggested intake may be as high as 0.1 mg per kg per day. ¹

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You Can’t Have it Both Ways

The people who promote this image as proof of the dangers of red 40, of course, ignore the pretty and quite healthy-looking hues of the other celery. If red 40 is bad are we supposed to also assume that green and blue food coloring is good? After all, the celery stalks seem quite happy. Such one-sided interpretations are ‘having your cake and eating it too.’

Lack of Experimental Control

The other major problem is the lack of control. The purpose of the original experiment was to show capillary action. This is, in fact, not an experiment but a demonstration. You cannot re-purpose a demonstration to suit your beliefs after the fact if the design of the experiment/demonstration is improper.

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In this case, the lack of a control makes the experiment invalid. A proper control may have been celery stalks placed in plain water and left for the same period of time as the celery in the food coloring. This would have eliminated any appearance changes that were due simply to the fact that celery only stays healthy for a limited period of time when stored this way.

It would also be a good idea to place multiple stalks of celery into multiple containers of water containing red dye to make sure the effect was constant. If you’ve read this far, you probably already know that the effect would not be constant.

Again, the healthy greenish color of the blue and green celery could be due to having taken up the colors, while they are, in fact, in no better shape than the celery placed in red color. While we cannot be sure about what is going on in the image, we can be assured that this image does not prove what is has been claimed to prove.