But Auckland University of Technology nutrition professor Elaine Rush said the uptake of the system had been slow, partly because it took time to change labels and partly because it was voluntary.
She did, however, say the ratings were helpful for consumers to choose within a product range.
"There are anomalies, however - fruit juice gets four stars and cheese scores much lower than low-fat, no-sugar yoghurt."
At the end of the day, it was always better to eat the correct portions of a variety of fresh and wholesome foods, Professor Rush said.
Before Nutri-Grain's "renovation", the cereal would have achieved only two stars, due to it containing 14 per cent of the recommended daily intake (RDI) of sugar and 8 per cent RDI of salt.
And major cereal producer Sanitarium "tweaked" some of its recipes - including products in the Light'n'Tasty range, which all have four stars - to enable products to rate well on the scale.
The company first adopted the star rating on Weet-Bix, which has five stars, in December.
The recent changes in recipes by the companies bodes well for consumers, and Food Safety Minister Jo Goodhew says Kiwis will be able to make better choices more easily based on the star system.
"It's a great way to help consumers make healthier choices quickly and easily when comparing similar packaged foods by taking the guesswork out of reading food and beverage labels."
By the end of this year, 500 own-brand products from New Zealand's two main retailers, Foodstuffs (New World and Pak'nSave) and Progressive Enterprises (Countdown), will be carrying the rating.
Though Ms Goodhew said there had been a strong uptake, a Ministry for Primary Industries spokeswoman said the number of products that had adopted the rating was unknown.
Last week, the New Zealand Beverage Council, which produces 95 per cent of all juice and non-alcoholic beverages here, announced it would adopt the star ratings on nearly all non-alcoholic beverages.
Consumer New Zealand head Sue Chetwin said having health stars prominently displayed on packaged foods would make it easier for consumers to identify better choices.
"The rating system is designed to enable quick comparisons of products within a category - for example, comparing one breakfast cereal with another."
She said because it was voluntary, its success would be influenced by the willingness of manufacturers to adopt the ratings.
"Some companies have started doing this but health stars aren't yet widespread on supermarket shelves.
"For the ratings to be useful, consumers will also need good information about how they work and how to use them so they can make better choices."
Health stars spur cereal-recipe tweaks
