Study Attempts to Determine if Mediterranean Diets Need to Be Organic

The Mediterranean diet, with its abundance of vegetables, whole grains, and olive oil, has been touted as a disease-preventing and nutritious diet.

But in a new study published in the American Journal of Clinical Nutrition, researchers looked at whether a Mediterranean diet filled with conventionally-grown foods may lead to an increase in pesticide residues in urine. They wonder if that may link to health issues and question whether an organic Mediterranean diet may be a better choice.

“There is evidence that a Mediterranean-style pattern of eating may lower the risk of cardiac disease, type 2 diabetes, and certain types of cancer,” says Erin MacGregor, RD, PHEc, a dietitian and nutrition communication consultant in Saugeen Shores, Ontario.

About the Study

In a 2-week randomized dietary intervention trial, 27 adults were assigned to follow a Mediterranean diet that was comprised of either entirely organic foods, or entirely conventionally grown foods. Both groups consumed a regular Western-style diet with conventional foods before and after the intervention period. In the 2-week study, all meal offerings were identical, with the exception of how the foods were grown—conventional vs. organic.

After testing, the researchers found that the urinary pesticide residue excretion (UPRE) was 91% lower for people following the organic Mediterranean diet vs. the conventional group. They also found that switching from the Western diet to the Mediterranean diet, with its increase in vegetables, increased UPRE as well.

“We know the benefits of eating fruit and vegetables far outweigh any health risk from the tiny amount of residues that we may ingest through our food supply,” says MacGregor.

It is also important to note that this study was funded by the Sheepdrove Trust, Drove Farm in the
U.K. which supports initiatives to increase organic farming.

Are Pesticides Worrisome?

This study provides evidence that the way our food is produced can affect the level of exposure to synthetic pesticides. However, it was not designed to address how the number of pesticide residues found in the study may affect long-term health.

When reading studies like this, it’s important to remember that finding pesticides in urine does not always equate to finding harm. It is important to remember that not all pesticides are toxic.

Carlos Leifert, PhD, a visiting professor in the department of clinical nutrition at the University of Oslo and one of the researchers on the study explains that “None of the pesticide residues we found in foods consumed during the intervention period was above the minimum residue level permitted by the European Commission.”

That is key because it means that even though the researchers found pesticide residues in urine, the amounts may have been small or non-harming. MacGregor points out that for something to be toxic, the dose must reach a certain threshold where it would be unsafe.

“If it’s 91% more than a very tiny amount, it would not translate to an unsafe amount of residue on food, and the value may be meaningless when it comes to the impact on health,” says MacGregor.

Dr. Leifert says that the researchers do not know whether the combination of pesticides they found in the urine samples from the conventional group is safe, but says “there is increasing evidence that they may not be.”

Researchers continue to look at the harmful effects of pesticides, including their potential role as endocrine disruptors, which can affect hormone levels. But this leads to more unanswered questions about whether small or safe amounts of pesticides lead to health problems.

“Endocrine disruptors have been a topic of conversation for a long time, and it is time we focus a little more attention on them,” says Sharon Puello MA RD CDN CDCES, a dietitian with F.R.E.S.H. Nutrition in New York, who often talks about pesticides and toxins with her clients.

The problem is bigger than just pesticides found in food, though. There can also be endocrine-disrupting chemicals in cosmetics, household cleaners, plastic packaging, clothing, toys, and more. It’s certainly an ongoing area of research, and something to be aware of.

Is a Conventional Mediterranean Diet Healthy?

Conventional or organic, there’s an abundance of research that supports the health benefits of the Mediterranean diet.

Puello says that “eating more fruits and vegetables of any kind is definitely more beneficial than sticking to the Western diet.” She explains that while you may have a higher intake of some pesticides, you also have a higher intake of antioxidants that have positive impacts on health.  

And what about the cost of organic food? Dr. Leifert says that in Europe, the price premium for many organic fruit and vegetables is small, making organic fruit and vegetables affordable. But that is not always the case in North America, where organically-grown food costs more than conventionally-grown food.

“Organic food often comes at a higher price because of the limited number of tools farmers have to control pests like insects or weeds,” says MacGregor. “This could mean it is less affordable and accessible to everyone.” 

“Getting healthier foods with fewer contaminants into the hands of everyone should be a universal goal,” says Puello. “With that said, as a society, we're not at that point right now where everyone has equal access to affordable, organically grown produce. However, that doesn't mean we
shouldn't push for change within our communities to get to that point.”