Have you ever found yourself standing in the supermarket, wondering how to justify forking out $6 per kilo for those organic carrots, when the non-organic variety cost just $2 per kilo?
For many of us price is a top consideration when we're buying food, even if we want to buy organic produce. So if you can't afford to buy only organic groceries, are there some organic products you should prioritise over others?
Well, that depends on your reason for wanting to buy organic produce in the first place.
Is organic more nutritious?
For those buying organic produce for health reasons, one of the major considerations is whether organic fruit and vegetables are more nutritious than conventionally farmed produce.
It's difficult to get a clear answer on this. That's because the nutritional quality of our fresh food varies widely, regardless of whether it's organic or not.
"You literally can't pick two apples off the same tree and get exactly the same nutritional profile," said Dr Liza Oates, who teaches Food as Medicine at RMIT.
Dr Oates says sometimes organic produce does have a better nutritional profile.
"It's true for certain nutrients in certain foods, but you can't say all nutrients in all foods," she said.
A review in 2014 found that organic fruit had higher levels of antioxidants than conventionally farmed fruit. But not everyone agrees on the what the results show.
"There's a lot of natural variation in the nutrition of the food we buy," said Dr Tim Crowe, a nutrition scientist at Bond University. "Variation from the climate, the soil it's grown in, and how it's processed."
Dr Crowe said next to no research has found that organic food is more nutritious.
"Only one lot of research potentially shows that organic produce might have higher levels of antioxidants than conventional produce — but not all studies show that," he said.
And even then, differences in antioxidant content between organic and non-organic food was only found to be significant in fruits, not in vegetables or cereals.
Dr Crowe said that if you are already consuming fruit and vegetables any nutritional benefit from organic produce would be very small.
Dr Oates thinks where you shop could make more of a difference to nutrition than selecting certain organic foods.
"People who consume organics tend to get a bit closer to the source which means they're probably eating food that has been harvested more recently, rather than food that's been in cold storage for long periods of time — that alone will probably have a bigger impact on nutritional value than the farming methods themselves," she said.
If you are avoiding chemicals
It's worth noting that in Australia the Food Standards Australia and New Zealand (FSANZ) sets maximum residue limits for all food products. These limits dictate how much agricultural or veterinary chemical or pesticide residue is legally allowed in a food product.
FSANZ states the maximum residue limits are set well below the level that could pose health and safety risks to consumers.
Organic crops on the other hand are not allowed to use synthetic pesticides at all.
So the bottom line is all fresh produce in Australia, organic or not, is monitored to make sure any pesticide levels detected are below the maximum residue limits and not a threat to our health.
The 'dirty dozen'
If you're someone who's worried about chemical residue on food, you may have heard of the "dirty dozen", a list of fruit and vegetables which when farmed using conventional practices have the highest pesticide residues, put together each year by American non-profit organisation, the Environmental Working Group (EWG).
The environmental advocacy group recommends that "for the items with the heaviest pesticide loads, we urge shoppers to buy organic".
But there are a few things you should know about the dirty dozen before you let it influence your shopping list.
This list is based on pesticide residue testing data of 48 foods by the United States Food and Drugs Administration.
"The problem is that there are different pests and pesticides used in different regions, and also different pesticide approvals around the world. So what happens in the United States isn't always reflective of what happens here," said Dr Oates.
Also, even though the list is known as the dirty dozen, the levels of pesticides detected on these items are well within the American legal limits.
Dr Crowe's assessment is that the dirty dozen list is "irrelevant, given the levels of pesticides detected on them are below those of any health concern".
One 2011 study investigated the methods behind the list and found that the most commonly detected pesticides don't pose serious risks to human health, that consuming the organic options doesn't significantly reduce any health risk, and that the methods used by the EWG lack scientific rigour.
But Dr Oates acknowledges that for many consumers, the issue it not about "pesticide residues being above or below the legal limits, they actually don't want any pesticides — they're trying to avoid them altogether.
"There are a few things we do know about the sorts of foods that are more likely to maintain residues," Dr Oates said.
"Things like pome fruits [apples and pears], berries, and some of the leafy greens and broccoli that have a large surface area and more space for pesticides to make their way in."
Environmentally conscious shoppers
One of the other major reasons people choose to consume organic food is because they believe organic food production is more sustainable than conventional practices.
"The main differences between organic and conventional food production is that organic farmers are not allowed to use water-soluble nitrogen and phosphorous fertiliser, and there's environmental impacts associated with those," said organic farming expert Professor Carlo Leifert from Southern Cross University.
The manufacturing of nitrogen fertiliser requires fossil fuels, and is therefore linked to their availability and price.
"You need about 1 litre of fuel to make 1 kilogram of fertiliser," Professor Leifert said.
Professor Leifert said that if you scale that up to a 1,000 hectare crop you need tens of 1,000s of litres of fuel to make the nitrogen fertiliser, which, if it's ammonium nitrate, can then release huge amounts of carbon dioxide into the atmosphere.
"That's a massive environmental impact from just one of the components of an agricultural system that organic farmers wouldn't use."
While organic farming does better in many areas of environmental impact, its main issue is that because yields are lower, more land is required.
So are there any products that have a larger environmental impact than others?
Professor Leifert suggests looking at how much fertiliser is applied to crops as a guideline.
"So on carrots, the differences in environmental impact are probably smallest because we use the lowest amount of nitrogen fertiliser in conventional farming for those, whereas on something like a brassica [such as broccoli], the impact would probably be in general bigger," he said.
Buying organic food: an individual choice
But one thing that is often missed in the debate about organic produce is the bigger issue that the vast majority of us aren't eating enough fruit and vegetables.
"Rather than focusing on getting a few extra antioxidants from organic produce, we should be trying to eat a lot more fruit and vegetables to begin with," Dr Crowe said.
But if you want to be a more sustainable fruit and vegetable consumer there are things you can do. For example, you can reduce food miles by buying local, in-season produce.
And, if you can afford to buy organic produce and you want to, then go for it.