If you cast your eyes over the labels on bottles of Primo Chocolate Milk and Value’s Standard Pasteurised Milk, you may find a shocking discovery: Chocolate milk is healthier than regular milk.

Primo proudly displays its 4.5 health star rating, while actual milk settles for just  3.5 stars.

But how? I’ve dedicated months seeking an answer, and it comes down to a surprisingly simple formula.

How does the health star rating system work?

The health star algorithm calculates healthiness but only “within specific categories,” says deputy director of New Zealand Food Safety Vincent Arbuckle. 

“It’s not meant to compare soft drinks and cheese,” he says. 

The health star rating system sorts items into categories like; beverages, cheese, non-dairy, oils, spreads, etc.  The amount of stars is determined by the item’s healthiness compared to other items in its assigned category.

This is how Kellogg’s Nutri-Grain cereal can score 4 health stars, despite being 24% sugar.

Or how KFC’s hot chips can earn 4.5 health stars, despite being from KFC.

Normally, you wouldn’t find these items in the healthy section of a food pyramid but within their categories, they’re the cream of the crop. 

So, is this how chocolate milk beats regular milk? Nope!  Turns out, Primo and Standard Pasteurised Milk both fall under the same ‘dairy beverages’ category.  There must be something else in that drink - something so diabolically simple, it earned a near perfect rating without anyone blinking an eye. 

What’s really in Primo Chocolate Milk?

It’s not a secret ingredient, but a secret weapon: Trim milk.  “Because it is made from trim milk, it has a lot less saturated fat than blue top milk,” explains Arbuckle. 

“Primo Chocolate Milk has only 0.1% saturated fat, which is 21 times less than Standard Pasteurised Milk which typically has 2.1-2.3%,” he says. 

He says the algorithm penalises saturated fats “as having too much increases your risk of heart disease”.

But what about sugar?  Decades of research shows how dangerous sugar can be. In fact, according to a 2016 article in JAMA Internal Medicine, the sugar industry quietly paid scientists in the 1960s to hype up the hazards of saturated fat while downplaying the serious effects of sugar. And surely sugar is something chocolate milk has a lot of? Primo Chocolate Milk does have slightly more sugar (6.7% per 100g) compared to Value’s Standard Pasteurised Milk (4.7% per 100g), but it’s not enough for the algorithm to care.  So, should you?

Should I listen to the health stars?

If you understand how it works, yes - but it’s not a perfect system.  

The companies are the ones who put their nutrients into an online calculator and the system is self-monitoring. So the accuracy is only checked if a query is raised. 

In 2018, Milo dropped its 4.5 health star rating because the rating was based on the assumption the malt and chocolate drink powder would be drunk with trim milk. But back then, Consumer NZ head of research Jessica Wilson said people didn’t use it with trim milk and told Newshub: “On its own the powder would only qualify for a 1.5 star rating.”

Even Arbuckle admits “it needs and is having tweaks”.  

He says the system underwent a wave of changes in November last year and those amendments included “the latest science from a range of experts to make the rating tougher on sugar and salt.” 

And it will keep changing.  As new research surfaces, adjustments will be made and Arbuckle says “it will be subject to ongoing review and refinement”.

So, this means Primo Chocolate Milk’s sweet 4.5 health star rating could potentially sour if the rules change or if it’s decided the health star ratings system is passed its use by date. 

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