What is the Mediterranean diet, and how it can be unhealthy? Switching from ‘Western’ foods to non-organically-grown fruit, veg and whole grains can TRIPLE the pesticides you consume and weaken your immune system, study warns

  • University of Oslo-led researchers studied different diets among 27 UK students
  • Non-organically grown produce is more susceptible to environmental contaminants 
  • This was found to be worse than the ‘British” diet.
  • Organically farming the same Mediterranean produce is better. 
  • It reduced pesticide levels by 90% when compared to nonorganic Mediterranean foods

Switching from ‘Western’ foods to a non-organically-cultivated Mediterranean diet may triple your pesticide intake and weaken the immune system.

This conclusion is from a study by researchers at the University of Oslo who compared the effects of different diets in a group of 27 British students.

The team found that produce farmed in the traditional manner passed on more environmental contaminants, which may affect fertility and juvenile development. 

The Mediterranean diet is rich in fruits, vegetables, whole grains and nuts, but low in red meat or dairy. It has been long hailed as a healthier alternative to British food.

While the fish part of the diet is low in environmental contaminants, non-organic farming of fruit, veg and whole grains passes on more pesticides.

However, the team noted, when the ingredients of the Mediterranean diet are farmed organically, such can slash pesticide intake by around 90 per cent.

Switching from organically-grown 'Western' foods to a conventionally-cultivated Mediterranean diet may triple your pesticide intake and weaken the immune system

Switching from organically-grown ‘Western’ foods to a conventionally-cultivated Mediterranean diet may triple your pesticide intake and weaken the immune system

Do I have to wash fruits and vegetables?

To remove pesticide residues from vegetables and fruits before they are eaten, it is important to wash them in water.

Produce is also at high risk from contamination by dirt, bacteria, and dust because it is stored in warehouses before being shipped in containers and then returned to retailers.

Food poisoning can result from the inability to wash fruits and vegetables, such as an E.coli outbreak. 

It is important to remove any soil as this is where bacteria lives.

NHS Choices suggests that you wash fruits and vegetables with running water.

The Food Standards Agency also suggests that you wash produce before using, but it will not completely eliminate any potentially-harmful residues. However, this will lessen those that are on the surface.

While peeling can be more effective, this method removes fibre as well as important nutrients such vitamin C. 

Friends of the Earth says organic produce is the best way to avoid pesticides.

Several of the environmental contaminants seen in the study are either known or suspected to affect hormones within the body, noted paper author and microbiologist Carlo Leifert, who is a visiting professor at the University of Oslo.

He explained that there is increasing evidence that these toxins can weaken the immune system and possibly even affect fertility.

“Hormones that are out of balance can also have a negative affect on the growth and development children.”

“Fruits and vegetables grown in the traditional way are some main sources of environmental pollutants absorbed through our diets.

“Mediterranean diets are based on such foods and have a ten-fold higher intake of these contaminants than those who eat organically grown foods.”

‘Both farmed and wild fish can contain environmental contaminants, but usually in small quantities,’ Professor Leifert continued.

The study involved 27 students who had never before tried ‘ordinary’ British food. They also kept track of everything they ate.

The researchers took a sample of their urine and shipped them off to Crete, where they stayed for two weeks. While there, 14 ate a diet of food cultivated traditionally, while the other 13 ate a diet comprised of organic produce.

Each participant’s urine was then tested again for contaminants like those derived from fertiliser usage before they returned home to spend another week on their normal British diet.

‘The group consuming a Mediterranean diet based on conventionally produced food were shown to have three times the level of environmental contaminants in their urine compared to when they were eating their normal, Western diet,’ Professor Leifert said.

Professor Leifert and his colleagues warned, however, that it is too early for health chiefs to start recommending against a Mediterranean diet based around non-organically grown produce.

They explained that the study group was small and that more research is needed.

Alongside this, environmental contaminants also enter our bodies from other sources such as skin creams and even the air we breathe.

The American Journal of Critical Nutrition published the study.


The Mediterranean diet emphasizes the consumption of more fruits and fish and fewer sugary drinks.

The diet emphasizes:

  • Fruits
  • Vegetables
  • Legumes
  • Nuts
  • Seeds
  • Whole grains
  • Fish and meat
  • Monounsaturated fats like olive oil are good options.

The diet should be followed by no less than the following:

  • Butter is an example of saturated fats.
  • Red meat
  • Foods that are processed, such as juice and whitebread
  • Soda
  • Sugar

However, in moderation, a glass of red wine here and there is fine.

How to follow the Mediterranean Diet

  • Eat more fish
  • Squeeze more fruit & veg into every meal
  • Extra virgin olive oil can be substituted for butter or sunflower oil
  • Nuts for snack
  • Eat fruit for dessert