Why does trim milk have sugar in it? It's a question I was asked recently in an interview, and it's not the first time it has come up.

There seems to be a common belief, in social media land especially, that trim dairy products have added sugar that isn't in the full-fat versions.

I think the confusion arises from the fact all milk and dairy products contain the natural sugar lactose. This means the nutrition label for any dairy product will list sugars.

However, when it comes to plain milk - full fat or trim - there is no added sugar. The only sugar in milk is from the lactose. Lactose is what's known as intrinsic sugar, and it's not sugar we need to worry about in our diet.

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The sugars we need to worry about are free sugars; these are added to foods and drinks or found in juices, syrups and honey.

The only time free sugars crop up in trim dairy products, like milk or yoghurt, is when the products are flavoured, such as chocolate milk or sweet yoghurt. The same goes for full-fat dairy products.

If you're comparing the labels on full cream and trim milk, you'll notice trim milk has a slightly higher amount - 0.2g per 100ml - of sugars listed. That's simply down to maths. When the fat is removed, the percentage of everything else goes up. That means there's a teeny bit more sugar.

There is also more protein and calcium, which are things worth having. Some people think trim milk tastes sweeter - that may be due to the higher natural sugar content and also the fact there's very little fat to round out the mouth-feel and flavour of the milk.

Homogenisation is another thing that gets people worried when it comes to milk. Trim milk is not usually homogenised, but higher fat milks are. Homogenisation is a mechanical process of emulsification.

Left alone, the fat in milk separates naturally from the water and settles on top (as in the old-fashioned silver-top milk). Homogenisation stops this from happening by forcing the milk at pressure through a valve.

There's no evidence that homogenisation does anything to the nutritional quality of the milk. And there's no evidence that homogenising milk is harmful, despite what you may read online.

Pasteurisation is the other process milk goes through that can create confusion. It's when milk is heated to kill bacteria that could make us sick. All commercially available milk in New Zealand is pasteurised.

According to MPI, "There's no substantial scientific evidence to suggest raw milk offers any health benefits over pasteurised milk."

On the other hand, raw unpasteurised milk can be harmful, especially to people with lowered immunity such as small children, the elderly and pregnant women.

Which milk is right for you comes down to your own situation. Just don't get sucked into the milk myths.

• Niki Bezzant is editor-at-large for Healthy Food Guide magazine.