The availability of foods designated “organic” has increased substantially over the past two decades. But choosing organic foods can also be an expensive proposition. Is it worth it? Is it worth choosing, say, lettuce or mushrooms that have not been produced with nitrogen- or phosphorus-based fertilizers, or chemical herbicides or pesticides? The USDA states that “Organic farming is a production system that excludes the use of synthetically produced fertilizers, biocides, growth regulators, and livestock feed additives such as antibiotics and growth hormones.” Organic farmers are therefore more likely to use manure or compost, periodically grow legumes that restore nitrogen to the soil, rotate crops, and use biological methods to resist pests. There is no question that consuming organic foods reduces exposure to the chemicals applied to crops in conventional farming. But is the extra expense worth it to your health?
An exhaustive review of the data addressing this question reveals that:
- Organic vegetables and fruit contain substantially greater quantities of polyphenols, antioxidants, anthocyanins and similar beneficial components (that exert much of their beneficial effects, by the way, through effects on the microbiome). Organic foods have 20-40% or greater quantities of these beneficial compounds.
- Organic produce have greater levels of carotenoids (e.g., beta carotene that is a precursor of vitamin A) and lutein (crucial for eye and skin health)
- Organic produce has higher levels of vitamin C.
- Conventionally grown vegetables and fruit have dramatically higher levels of cadmium, a toxic heavy metal that increases risk for heart disease and various cancers. This may be the most important factor of all distinguishing organic vs. conventional vegetables and fruit. Cadmium accumulates in the body and is inefficiently cleared, meaning that minimizing exposure to cadmium can be a major issue for health. Organic foods had, on average, 48% lower cadmium levels, likely due mostly to the fertilizers chosen—a huge difference, especially when amplified by accumulation over time.
- Not surprisingly, levels of pesticides in conventionally grown produce were four-fold greater. Exposure to pesticides appears especially important with fruit, less with vegetables. (The 11% of organic crops with detectable pesticide levels are presumably due to contamination from neighboring non-organic farms or persistence of pesticides in the soil from prior usage, or, of course, fraud in making organic claims.)
- Quantities of zinc and magnesium are modestly higher in organic crops (which are major factors in protection from gastrointestinal cadmium absorption).
In short, organic vegetables and fruit had greater nutritional value of a number of key nutrients, had little pesticide residues, and substantially less cadmium.
The reduction in cadmium is especially interesting. While cadmium is unquestionably an acute deadly toxin, the evidence for long-term low-grade toxicity is observational and therefore cannot firmly establish a cause-effect relationship. Populations with greater cadmium exposure appear to have modestly higher incidences of cancer and cardiovascular disease. The International Agency for Research on Cancer designates cadmium as a group I human carcinogen and it has been associated with lung, breast, prostate, pancreas, urinary bladder, nasopharyngeal cancers, and non-Hodgkin’s lymphoma. Cadmium exposure is also a potential cause of hypertension, kidney disease, benign prostatic hypertrophy, and osteoporosis. Evidence is also growing suggesting an additive or even synergistic health impact of cadmium combined with pesticide exposure.
What this and similar analyses cannot tell us is whether such differences between organic and conventionally-raised foods make a difference in health outcomes. Does consuming organic foods result in less heart disease, cancer, and other health conditions? Observational (and thereby only hypothesis-generating, not making cause-effect connections) evidence suggests, for instance, that obesity, cancers such as non-Hodgkin’s lymphoma and breast cancer, and neurodegenerative diseases are increased by pesticide exposure. The list of potential chemicals that we are exposed to via conventional farming also continues to grow. By choosing organic, for instance, you avoid exposure to butylated hydroxyanisole, polysorbate 80, hydroxypropylmethylcellulose, and hundreds of other chemicals.
Studies that establish cause-effect associations are expensive, require huge numbers of participants observed over many years, and are largely impractical—would you participate in a 10-year long study if you were assigned to consume only pesticide-containing conventional foods? Concerningly, a recent animal study that observed animals consuming organic vs. conventionally-grown food showed that endocrine and immune effects carried over into the subsequent generation, likely due to epigenetic transmission. In other words, the health effects of some chemicals used in conventional farming can be passed onto your children and grandchildren, even if they are not directly exposed.
Thankfully, the choice between organic and conventionally-produced foods is becoming easier as more organic foods become available and the price differences are shrinking. Organic farming is also better for the environment, as the huge amounts of chemicals are not being introduced into the environment, changing soil microbes, affecting birds and other creatures, not draining into ground water or air.
All in all, whenever you have a choice, choose organic. The Environmental Working Group maintains a database of conventionally-farmed foods high in pesticides, as well as those that are relatively safe.