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Plain vs Flavoured Yoghurt: Where Does the Sugar Come From?

Published · Updated  · Sláinte Editorial

Look at a tub of plain yoghurt and you may still see sugar on the nutrition table.

That does not automatically mean someone added table sugar to it.

Illustration for Plain vs Flavoured Yoghurt: Where Does the Sugar Come From?

Milk naturally contains lactose.

The ingredients list helps explain where the total sugar number comes from.

The two products

Glenisk Bio Organic Whole Natural

Per 100g:

  • 69 kcal
  • sugars 3.3g
  • protein 3.3g
  • fat 4.2g

Glenisk Bio Organic Whole Mango & Vanilla

Per 100g:

  • 94 kcal
  • sugars 10.3g
  • protein 2.8g
  • fat 4.2g

The flavoured product’s ingredients include cane sugar.

Why does plain yoghurt contain sugar?

Because milk contains lactose.

That naturally occurring milk sugar appears in the total sugars value on the nutrition declaration.

So 3.3g sugars does not automatically mean 3.3g added sugar.

Total sugar is not added sugar

EU nutrition declarations generally give a value for of which sugars.

That is total sugars.

It does not automatically separate naturally occurring lactose from sugar added during manufacturing.

The ingredients list is therefore important.

Can we calculate the added sugar by subtraction?

No.

It may be tempting to say 10.3g minus 3.3g equals 7g added sugar.

That would assume the two products have identical amounts of every naturally occurring sugar and ingredient.

We do not have enough evidence to make that calculation.

The accurate statement is: the flavoured yoghurt has a higher total-sugars value and lists cane sugar as an ingredient.

Protein

The plain yoghurt listing gives 3.3g protein per 100g.

The mango and vanilla listing gives 2.8g per 100g.

Again, this describes the exact products.

Fat

Both researched products listed 4.2g fat per 100g.

That is useful because it prevents another common shortcut: flavoured does not automatically mean lower fat, and plain does not automatically mean higher fat.

Read the actual label.

Does organic mean lower sugar?

No.

Organic status and sugar content answer different questions.

An organic product can contain added sugar. A conventional product can be unsweetened.

What about live cultures?

Yoghurt products may contain live cultures.

If an article discusses specific digestive or probiotic benefits, those claims need their own evidence and must comply with the relevant health-claims rules.

Total sugarcheck ingredientsdistinguish naturally occurring sugars from added sweetening ingredients

What this means when you’re shopping

For yoghurt, check:

  • Total sugars.
  • Ingredients.
  • Protein.
  • Fat if relevant to your choice.
  • Portion size.
  • Whether sugar-containing ingredients have been added.

Frequently asked questions

Why does plain yoghurt contain sugar?

Milk naturally contains lactose.

Is all yoghurt sugar added sugar?

No.

Does low-fat yoghurt always contain more sugar?

No. Check the exact product.

Does organic yoghurt automatically contain less sugar?

No.

Can I calculate added sugar from the total sugar figure?

Not reliably from the standard nutrition table alone.

The short version

  • Plain yoghurt can contain naturally occurring milk sugars.
  • Total sugars does not mean added sugars.
  • The ingredients list adds essential context.
  • The flavoured example has more total sugars.
  • Its ingredients include cane sugar.
  • Do not calculate exact added sugar by subtracting two different yoghurt products.
  • Organic does not mean sugar-free.

Keep reading

Sources

Last reviewed: 5 October 2026