Overview

For over 10 years, New Zealanders have been presented with the concept of a "food pyramid", meant to represent a healthy approach to eating. The idea is simple: you're supposed to eat lots of the food at the base of the pyramid, and just a little of what's at the top.

The original Food Guide Pyramid was invented by the US Department of Agriculture in 1992, and was adapted for New Zealand by the Heart Foundation and Cancer Society.

The New Zealand version is taught in our schools as part of the health curriculum, is available on various websites, and is promoted by some health organisations. But readers may be surprised to learn that it is not part of the official guidelines for New Zealand nutrition. The reason? In some important respects, it's out of date.

The pyramid contains some key messages on which all nutrition experts agree - chief among them, that everyone should eat lots of vegetables and fruit.

But the Food Pyramid does not reflect some messages that are now known to be vital to good health. In particular, it doesn't differentiate between different types of fat, between different types of carbohydrate, and between different types of protein.

Due to its simplicity it needs to be accompanied by other messages about serving sizes and food types.

But medical researchers at the Harvard School of Public Health, led by a widely respected professor of nutrition, Dr Walter Willett, have gone a lot further than that.

Based on very large population studies and what they say happens in our chemistry when we eat (see The science of food), they have advocated that the Food Pyramid be scrapped. In its place, they have proposed a different pyramid, which they call the Healthy Eating Pyramid.

Are they right? And what do the New Zealand food health authorities have to say?