The Kiwi diet: When's the right time to intervene?

By Martin Johnston

Government policy on eating habits is changing, with money being diverted to maternal and newborn nutrition from other food programmes. Health reporter Martin Johnston looks at the evidence and the controversy.

Arti Dzonge says she changed her diet to protect Joshua, who is now 11 months old. Photo / Richard Robinson Photo / File photo
Arti Dzonge says she changed her diet to protect Joshua, who is now 11 months old. Photo / Richard Robinson Photo / File photo

When the National Government started switching off healthy-eating policies in the midst of an epidemic of obesity, many health experts were dismayed, but not shocked.

The administration's latest swerve in food policy - to divert money from healthy-eating policies targeting people of any age and into maternal and newborn nutrition programmes - has now managed to shock some.

"Nobody disputes that mothers and young children should be well nourished," says Jim Mann, professor of human nutrition and medicine at Otago University.

"Is it [the change in policy] likely to be beneficial as a public health measure? No evidence whatsoever. But there's interesting animal evidence and some human evidence. Good for future research."

Professor Mann sounds like he's marking an undergraduate essay. In fact, he's assessing the political application of the work of the highly decorated medical scientist, Professor Sir Peter Gluckman, the Prime Minister's chief science adviser.

He pays tribute to Sir Peter as "a very good scientist, but he's not a public health person".

In half a lifetime, New Zealand's adult obesity rate has nearly trebled, to 28 per cent. Ten per cent of children are obese.

Seven per cent of adults have been diagnosed with diabetes and a further 19 per cent are in the pre-diabetic state. Obesity is a risk factor for developing type 2 diabetes and heart disease.

Many public health researchers want changes to the food "environment" - the easy availability of cheap, highly-processed, energy-packed food and drink - but politicians, especially from right of centre, are reluctant to make these interventions in the market.

Against this background, Sir Peter's advice has been central to the Government's changes.

Health Minister Tony Ryall and Associate Health Minister Jo Goodhew have repeatedly cited his public statements on nutrition and this advice is about to be put into action.

Mr Ryall: "We have been working with ... Sir Peter Gluckman on the best point of intervention for obesity. Professor Gluckman suggests that pre-conditions for obesity are set very early and the best intervention point is maternal and newborn nutrition.

"Funding previously allocated under the Healthy Eating Healthy Action strategy is now being shifted to this new priority area to improve maternal and child nutrition and physical activity."

Ms Goodhew says that as contracts expire, the Government will re-prioritise funding to improve:

•Healthy weight-gain and nutrition education during pregnancy;

•Nutrition education and support for babies, infants and pre-schoolers.

The new programmes are being finalised, with an expected start date of July 1.

The Government spends about $50 million a year on nutrition and physical activity programmes; the previous, Labour-led Government was spending about $65 million a year.

Sir Peter seems uneasy to be identified as the heart of the apparent change of policy focus.

"I don't want to get into criticising Jim [Mann] because he's a fine upstanding person. This is what I'm worried about, that we're getting camps developing, when it's an and approach."

By which he means - as he and colleagues wrote in the journal Science Translational Medicine - that the need for early-life intervention "is not to say that current initiatives should be reduced". "Society must care for those adults who are already ill and assist those who are far along the pathway to disease. However, these activities in themselves are clearly insufficient to halt the rise in obesity and related diseases. Focus on the adult alone will have limited effects ..."

But the Government's version of this in its new focus on maternal and newborn nutrition has been interpreted by Professor Mann and others as ignoring the obesity of everyone older than one.

"We are just going to see everything get worse and worse, when we know that there's evidence that we can do something in school-aged children ... [and] for middle-aged men and women who are pre-diabetic."

Sir Peter's argument, from the journal article, is this: "There is compelling evidence of a sizeable contribution of early-life influences on the risk of becoming an obese adolescent or adult and of developing obesity-associated diseases in adulthood."

The article notes the evidence that being born small or premature increases the risk of later obesity and associated diseases.

Human research by the Liggins Institute and its international partners showed in 2011 that a mother's diet could alter the functioning of her child's DNA, leading to the child later storing more fat.

Sir Peter's article goes on to state that the early transition of infants from breast feeding to bottled formula increases the risk of developing childhood obesity by about 20 per cent. It is uncertain whether this is due to over-nutrition, changes in learned feeding behaviour, or changes in gut microbes.

The authors also cite the suggestion that food preferences appear to be set early "and can be influenced by maternal food intake in-utero and during lactation".

Part of Sir Peter's focus on early life is to help break what others have called the cycle of obesity and gestational diabetes - diabetes that comes on during pregnancy and resolves afterwards.

Professor Elaine Rush, of Auckland University of Technology, notes children of mothers with gestational diabetes are themselves at increased risk of obesity and type 2 diabetes in childhood and adolescence. "In effect a cyclical relationship could develop, where obese and diabetic mothers give birth to infants who become obese and develop diabetes before their child-bearing years, only to pass this on to their offspring," she and colleagues have written in the NZ Medical Journal.

Gestational diabetes

5.5 per cent of NZ European women had gestational diabetes
10 per cent of Maori
17 per cent of Pacific
15 per cent of Asian
22 per cent of Indian
7 per cent of other European
13 per cent of other ethnicities

Source: Auckland DHB report on births at National Women's in 2011

- NZ Herald

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