Is organic food better for me?
There have been a number of claims which suggest that food grown organically is healthier and more nutritious, and many of us are prepared to pay a premium for organic food because we think it is better for us. But is it?
If you look beyond health effects there are lots of reasons why people choose to buy organic food.
For some people it’s an ethical and environmental choice; organic food uses fewer pesticides and less intensive farming methods.
But we wanted to put the health related beliefs to the test. So Dr Chris van Tulleken teamed up with Dr Catherine Birch and Professor Graham Bonwick from the University of Chester to run a number of tests to find out if it is worth spending our money on.
The Taste Test
Firstly, we wanted to find out whether the way organic food is produced actually makes it more flavoursome.
For this informal test we selected organic and non-organic equivalents of carrots, apples and tomatoes from a single supplier, and matched them in terms of agricultural variety and appearance. Chris then set up his own market stall in the centre of Chester and asked volunteers to taste the organic and non-organic produce and rate which one they preferred.
We found that more people preferred the organic apples and tomatoes, but interestingly, most people preferred the non-organic carrots.
So although it was not the most robust scientific test it does seem that the non-organic food is not a million miles behind the organic food in terms of taste.
The Pesticide Test
In our second experiment, we tested the pesticide residue of both organic and non-organic food to compare in the levels of harmful chemicals they contain.
Graham and Cath used a very simple broad spectrum test to determine the presence of a multitude of different commonly used pesticides including carbamates like Aldicard, Carbaryl, Carbofuran; organophosphates including Methamidophos, Mevinphos; and thiophosphate pesticides like fenitrothion, malathion, parathion. A positive result using this test indicates the presence of these compounds at concentrations above certain detection limits.
In the organic food sample we found no detectable pesticides.
But we found that our non-organic food did contain ‘trace amounts’ of pesticides. Based on the extraction methods, the pesticide concentrations in the original sample would have been greater than the following values:
- Carbamates - 50 parts per billion
- Organophosphates - 40 parts per billion
- Thiophosphates - 50 parts per billion
But, these are considered to be levels which a safe for human consumption. And so really you shouldn’t be worried at all.
Of course, pesticides affect the environment, so that is one reason for buying organic. But as far as your health is concerned, current scientific research suggests that the fruit or veg sold in the UK does not contain levels that could be harmful – whether organic or not.
The Nutrition Test
Finally, we wanted to find out whether organic food is more nutritious. For this, Graham tested the vitamin C and total polyphenol content (chemicals produced by plants thought to be very good for our health) of our fruit and veg samples.
In this test he found no significant difference between conventional and organic produce. This result reflects published research done in other labs.
When you’re out buying fruit and veg, is it true that it doesn’t matter what you buy in terms of your health?
Interestingly, it seems that Vitamin C and other key nutritional components of food are known to be affected by factors such as handling and storage conditions. Vitamin C is by far the least stable nutrient during processing and storage partly because it is highly sensitive to oxidation. So the retention of vitamin C is often used as an estimate for the overall nutrient retention of food products.
So Graham and his team tested three different kinds of carrot to evaluate the impact that storage conditions can have on their nutritional composition: fresh organic carrots purchased from a supermarket, the same carrots which we then kept in the cupboard for 4 days and frozen carrots.
The fresh carrots had a healthy vitamin C level of just above 730mg per kilo but we found that after 4 days this level drops over 10% down to 630 mg per kilo.
In most studies freshly picked vegetables consistently contain the greatest amount of vitamin C However, vitamin C begins to degrade immediately after harvest and will degrade steadily during prolonged storage (although refrigeration can slow the degradation). But that loss of nutritional content because of storage affects organic food just as much as any other.
So how can we get the most out of our vegetables?
Well, in our test we found that the frozen carrots contained even more vitamin C than their fresh counterpart – a whopping 740mg per kilo.
This is because frozen food is often frozen within an hour of being harvested. So the vitamin C is not given a chance to degrade.
So although there are lots of good environmental reasons to eat organic food, there isn’t much evidence of an increased benefit to your health. If it’s maximum nutrition you’re after your best bet might be to reach into the freezer compartment.