In the first of a five-part series on the pros and cons of ethical shopping, we look at healthy food choices.
How can I make sure the food I buy is healthy?
The usual answer to this question is a simple checklist - eat lots of fresh, seasonal fruit and vegetables, avoid heavily packaged and processed foods and make your own meals instead of buying ready-made.
It's good advice but everybody cuts corners and the trick is knowing how and when to do it. For instance, canned fruit in unsweetened juice has about as much nutritional value as fresh fruit, possibly more if the "fresh" fruit has been kept in a coldstore for months.
And as Weekend Herald food columnist Wendyl Nissen has discovered, greater consumer awareness means some packaged meals are now made with natural ingredients, instead of a soup of chemical additives.
How do I make sense of the mass of information on food labels?
You probably can't, says food campaigner and former Green MP Sue Kedgley, because manufacturers swamp you with numbers.
"I almost think it's deliberately deceptive, so they can say they've divulged how much fat and sugar there is in a product but it's almost impossible to work it out."
The trick, she says, is to ignore serving size and daily intake calculations and check the percentage column. This will reveal, for instance, that Kellogg's Nutrigrain - which is marketed as a health cereal - contains 33 per cent sugar, more than Coco Pops. A 2009 Consumer survey found Sanitarium Toasted Muesli Golden Oats & Fruit had 16 per cent fat and warned "the ingredients list on Hubbards Caramel Cashew Crunch Muesli reads more like a dessert".
Why can't they come up with a clearer system?
A report to New Zealand and Australian food ministers last year recommended "traffic light" food labels, showing sugar, fat and salt levels as green (low), orange (medium) or red (high). Last month the politicians rejected this idea but surprisingly agreed to introduce some form of interpretative labelling - which tells a shopper how good or bad the food is for them - within a year.
One possibility is a three tick or three star system similar to the energy ratings used on fridges and washing machines.
Wouldn't that make choosing healthy food a lot easier?
One danger is that an oversimplified system gives misleading signals. The three tick system proposed to the US Congress would give three ticks to Diet Coke but only two to nutrient-rich milk because of its fat content. The food industry argues that this proves no product should be considered good or bad in itself - what matters is each person's overall diet. For this reason many manufacturers show their food's ratings as a percentage of a person's recommended daily intake based on a typical serving size.
Consumer magazine points out three problems with this argument. Any food's "recommended daily intake" varies hugely between individuals, especially adults and children, and there are no standard serving sizes, meaning manufacturers can choose a number that suits them.
The system also requires you to calculate your likely daily intake of other foods, which most people won't bother to do, even if they know how.
"If you're doing that for every item you're putting in your weekly shop, you'd be there for hours probably," says research writer Jessica Wilson. "So a simple system like traffic light labelling has benefits and we think could help consumers make better food choices."
* Tomorrow: Organics