How Organic Produce Affects Pesticide Exposure

Dr. Rhonda Patrick: The first question was submitted by David. David asks, “Rhonda, it is time to really look at whether organic produce is healthier than conventional produce, especially with regard to pesticides.”

I was happy to do a deep dive on this question because I had been wondering the same thing about pesticide exposure in organic produce. A lot of organic produce is grown close to conventionally grown produce, so I had wondered whether pesticides were making their way to the organic produce because of the proximity. Let us look at the data.

I was surprised to find some good and reassuring data. Before we discuss pesticides, let us talk about nutritional differences.

Probably the most comprehensive study comparing the nutritional value of organic and conventional produce included about 656 analyses. It concluded that there is not a large overall difference. The result may depend on the type of produce and the nutrient being examined.

That is not surprising because the soil, crop, water, fertilizer, manure, harvest timing, and other factors can all affect nutrient levels. An organic tomato from one farm may be very different from an organic tomato from another farm. The comparison is not only conventional versus organic. Where the produce is grown and the soil also make a difference.

Organic produce typically had higher levels of some micronutrients, including vitamin C, magnesium, and potassium. It was also generally lower in some heavy metals and nitrites. However, some conventionally grown produce was higher in beneficial carotenoids such as lycopene and beta-carotene, and in manganese, an important trace element. It depends on the food. We cannot make one blanket statement comparing conventional and organic produce.

Polyphenol levels can also differ. Plants often make these compounds to defend themselves from insects or fungi. If produce is sprayed with pesticides, it may face fewer insects and have less of a polyphenol response. Many organic crops experience more natural stress from fungi and insects, and in many cases they have higher polyphenol levels. The data are mixed, but this is another point to consider.

Now let us shift to pesticide exposure. I have heard some people say that organic produce is meaningless and that it exposes you to as much pesticide as conventional produce. The scientific literature does not support that claim.

The clearest and most consistent finding is that switching from conventionally grown produce to organic produce reduces pesticide exposure. This is empirical evidence based on pesticide metabolites. Total urinary pesticide residues can be about 91 percent lower. Glyphosate can be 71 percent lower, and AMPA, the primary glyphosate metabolite, can be about 77 percent lower within days of switching from conventionally grown fruits and vegetables to organically grown fruits and vegetables.

Similar reductions have been observed across multiple pesticide studies. When pesticide metabolites are measured in urine, their concentrations fall significantly after switching to organic food. That is reassuring.

One study included in the review found that when children switched to an organic diet for 40 days, they had lower pesticide metabolites and lower markers of oxidative stress, including DNA damage and lipid peroxidation.

DNA damage can potentially lead to mutations that contribute to cancer. This is one proposed link between pesticide exposure and cancer, particularly in people with high occupational exposure. These workers are exposed to much higher pesticide levels than someone who eats conventionally grown produce.

Lipid peroxidation means that oxidative stress is damaging the lipid membranes around cells. That can impair cell function. For example, damage to endothelial cells that line the vascular system can make them stiffer, which is not good for cardiovascular health.

I think this is strong evidence that switching to organic produce lowers pesticide exposure and can affect health biomarkers such as DNA damage and lipid peroxidation.

We can also look at studies of pesticide exposure and disease risk. This evidence is observational. Much of it comes from occupationally exposed people who work with pesticides. The evidence is strongest in these groups.

Studies have linked pesticide exposure with cancer, metabolic dysfunction, thyroid dysfunction, fertility problems, neurodevelopmental problems, and Parkinson's disease. There are good reasons to reduce pesticide exposure, but these studies show associations and cannot by themselves prove causation.

The practical takeaway is that if you are concerned about pesticides and can afford organic produce, it is a reasonable choice. I realize that organic produce is expensive and many families have limited budgets. In that situation, the Dirty Dozen and Clean Fifteen lists can help prioritize fruits and vegetables. Some foods are more likely to carry pesticide residues, while others tend to have less.

At the end of the day, the large body of scientific literature shows that the health benefits of eating fruits and vegetables outweigh the potential risks. Most studies of produce consumption do not separate organic from conventional produce, and most people do not eat only organic food. Eating fruits and vegetables is beneficial. If possible, you can still use residue information to decide which foods to buy organic.