Azo dyes are the colouring agents of choice - they account for three-fifths of all food dyes manufactured and why not ?  They're significantly brighter than their artificial alternative, the anthraquinones and they come in a variety of colors, the yellows, the oranges, the reds and any combination of the three.  In some cases they're even fed to chickens to make egg yolks more yellow.  If their use is so widespread then they must be safe to consume, right ?  Not necessarily.  Azo dyes are increasingly unpopular abroad with the ingredient having been banned in major European countries including Germany, the United Kingdom, Norway and Austria with bans in Germany and Austria lifted only after being re-evaluated for the third time by the European Union Scientific Committee For Food.  Kraft Dinner's original entrée remains colored by the dye but only in North America. 

So how might Kraft Dinner be found in countries where the dye in question (Yellow 5) is banned ?  Substitutes !  They may be slightly more expensive but when they're the difference between a brand staying or leaving, they become the ingredient of choice.  For large companies profit remains the main motivating factor, so when a company is presented with two options .. one being a natural ingredient that fewer people have an intolerance towards, the other a cheaper-to-make artificial coloring agent that also happens to be more stable to use/blends better with other ingredients, which option do you think wins ?  Nothing short of a ban on the ingredient would cause companies to choose the more expensive/harder to use option #2.  Health authorities are integral to this process as they have been instramental in forcing companies to remove the substance from their products.  Canada and the United Kingdom prove this;  In the UK the six main azo coloring agents were phased out in 2010 mainly due to studies done at a number of institutions including Southampton University.  One study estimated that the number of people with ADHD could potentially be cut by one third simply by getting it out of children's foods.

In Canada, Kraft Foods was presented with a petition signed by over 300 thousand Canadians wanting the company to replace the ingredient with something more natural.  In response the company didn't change a thing even though it wouldn't have been difficult to do given that Yellow 5 is not used in Kraft Dinners sold outside North America.

What exactly is tartrazine and what gives it its attractive bright yellow color ?

Tartrazine is an azo compound whose general form is that of a double bonded pair of nitrogen atoms each linked to different organic groups causing most of their electrons to become delocalised.  This delocalization means the molecules have a strong interaction with light, and hence can have a powerful colouring effect.

Side Effects

The list of potential side effects is long and includes hyper-activity, restlessness, adhd.  Also note that Yellow 5 is not too dissimilar to Red 3 in terms of chemical structure and Red 3's carcinogenic effects are recognized by the FDA - causes thyroid tumors in rats.  It isn't just the direct side effects that are concerning .. it's the rise in allergic reactions to other substances.  Research has also linked it to migraines, asthma and rashes. 

World Remains Divided On The Issue of Tartrazine

Fast forward to 2013 and we see that the world remains divided on the issue of whether or not Tartrazine is safe for consumption.

Countries where tartrazine or related dyes are either banned or being phased out - United Kingdom, Norway, Austria, Finland

Countries where ban had been in place until the European Union got involved - Germany, Italy, Czech Republic, others

Maybe tartrazine isn't so bad after all...

In 2009 the European Union Scientific Committee for Food (SCF) conducted its 3rd evaluation of the safety of tartrazine (others were in 1975 and 1984) after establishing an acceptable daily intake (ADI) of 0-7.5 mg/kg per day.  It was the 2009/2010 re-evaluation that ended up getting bans lifted in a number of EU countries including the largest Germany.  Using more recent study findings which were critical of the dye, the panel concluded not only that tartrazine is not carcinogenic (nuclear dna migration in rates can't result in increased carcinogenicity) but also that "the findings of the study cannot be used as a basis for altering the ADI" (Tanaka study).  ‎

Though the debate continues to rage on in America it is interesting to note that another yellow dye known as quinoline yellow is already banned in the USA (along with Japan, Australia and Norway... though not Canada). 

Potential Substitutes

tumeric, beta carotene (think carrots :) ), annatto, malt.