What makes food healthy? I’d venture to guess that there are two considerations: what it has in it (proteins, carbohydrates, fats, vitamins, antioxidants, and other nutrients) and what it doesn’t have in it (harmful bacteria, plus pesticides and other natural and synthetic chemicals that might harm us).

I’ve already pointed out that organic food might contain residues from the use of natural pesticides. These residues can be just as toxic as synthetic ones, if not more so. Moreover, organic food contains chemicals made by the plants in their own defense. So choosing to eat organic food may not necessarily protect us from all pesticides. It depends more on which particular pesticides were used by the grower, how much, and how often.

But what about bacteria? Is organic food safer from contamination? When growing crops, you might think that using manure instead of synthetic fertilizer would increase the risk of fecal contamination. But a recent study by the University of Minnesota found that isn’t always the case: 1.6% of conventionally grown produce contained E. coli (the bacteria studied), while 9.7% of the organic produce was contaminated. However, mandated precautions on certified organic farms reduced the bacterial level to 4.3%, which wasn’t statistically different from the 1.6%.

My conclusion? Wash your produce before you eat it, no matter where it was grown!

What about meats? Despite the widespread use of antibiotics in conventional agriculture, both organic and conventionally grown meats are highly contaminated with disease-causing organisms. It’s best to assume that the meat you buy is laden with bacteria. However, organic meat had a much lower level of bacteria resistant to three or more antibiotics. That sounds great, but no one knows if antibiotic use in agriculture is related to antibiotic resistance in bacteria infecting humans (e.g., “superbugs” such as MERSA).

So much for what we’re trying to avoid—how about nutrition? Is organic produce more nutritious? Many organic devotees claim that “feeding the soil” increases nutrients in the plants that grow there. It seems logical—ensuring that plants have all the nutrients they need should result in a healthier harvest. And it’s certainly true that if the soil lacks a particular element, it won’t be there for the plant root to take up.

Surprisingly, a 2012 study at Stanford found no significant difference between the nutritional levels of organic vs. conventionally grown produce. The researchers concluded, “The published literature lacks strong evidence that organic foods are significantly more nutritious than conventional foods.”

A more recent study disagrees with these findings. Researchers in England and at Washington State University found that organic vegetables contain more antioxidants—18% to 69% more! Interestingly, this is because plants grow organically are more stressed, especially by predation. It would follow that organic growers who use a lot of (permitted) pesticides wouldn’t see this advantage in their veggies. An article describing the study’s results stated,

Without the synthetic chemical pesticides applied on conventional crops, organic plants tend to produce more phenols and polyphenols to defend against pest attacks and related injuries. In people, phenols and polyphenols can help prevent diseases triggered or promoted by oxidative damage, like coronary heart disease, stroke and certain cancers.

(There was much more than I can cite here; I highly recommend reading the entire article.)

Finally, yet more studies found the opposite! As reported in The Telegraph:

… analysis found that the standard broccoli contained slightly higher levels of antioxidants compared with the organic version. The conventionally-grown potatoes had a higher level of vitamin C. … A separate study found there are no extra health benefits to eating organic food rather than meat, fruits or vegetables grown on intensive farms.

So perhaps there is some basis for the claim that organic food is healthier—or perhaps not. The differing conclusions may be due to the large number of variables involved in growing anything—rainfall, temperatures, fertility, pests, cultivars, etc.—not all of which are easily controlled. Clearly, more research is required.

But what about taste? While it’s not directly related to health, does organic food taste better? I’ll look at that next month.