You don’t have to go very far in a grocery store before you see “organic” sprinkled about like confetti in Times Square on New Years Eve. It’s common to hear claims about the superiority of organic food over non-organic food including:

• better nutritional profile (higher levels of nutrients)
• absence of synthetic pesticides and herbicides (making assumptions that such compounds are harmful and promote diseases such as cancer
• better health outcomes

While it would be nice if we could all eat organic everything all the time, the price difference can be substantial, paying up to twice the cost for organic products. So this raises the question, what does the evidence say? I’m a scientist so I care what the data shows, but as a consumer, I’m also curious to know if I should shell out for the perceivably superior products or if I’m completely wasting my money.

Nutritional Quality

By quality, I’m referring to nutritional content, i.e. actual levels of dietary micronutrients and bioactive food components such as polyphenols between organic and conventional foods. It’s assumed that organic products are nutritionally superior, but is this supported by the evidence? Let’s look at both plant and animal produce.

Plant Produce

In 2009, Dangour et al. conducted a systematic review of studies that compared the nutrient content of conventional and organic foods through chemical analysis (standard method). They included 55 studies in the review and there was no difference in the crop-produce between organic and conventional methods for 10 out of 13 categories analyzed. The three studies that did show a difference is likely reflects a difference in fertilizer and ripeness of the product at the time of harvest. There were no differences between organic and conventional for nutrients like vitamin C, zinc, copper, potassium, magnesium, calcium, and phenolic compounds.

A more recent review in 2012 by Smith-Spangler et al. reported similar finding with no difference in nutrients between organic and conventional produce. They did find phosphorus and total polyphenol content was higher in organic produce, but no difference in vitamin C, beta-carotene, alpha-tocopherol, magnesium, calcium, and iron. Conversely, Brandt et al. reported a significantly higher vitamin C but no difference in carotenes, tocopherols, or anthocyanin (antioxidants).

The most recent systematic review and meta-analysis by Baranski et al. included 343 studies and found that antioxidant activity was on average 17% higher in organic crops. Moreover, polyphenolic compounds were significantly higher, with a range of 18-69% higher concentrations, depending on the specific compound. Interestingly, levels of proteins (amino acids), fiber, and vitamin E were all lower in organic crops compared to conventional crops.

Taken as a whole, the evidence from the studies suggest that, compared to conventionally grown crops, organic crops may contain:

• Higher levels of antioxidant compounds (consistently shown)
• Higher levels of vitamin C (inconsistently shown)
• Potentially higher levels of carotenoids (inconsistently shown)

To put this in perspective, an analysis of broccoli samples obtained from commercial supermarkets demonstrated differences in the nutrient content of vitamin C related to the season of harvest, but no difference between organic and conventional. Perhaps the wisest thing is to eat in season.

Animal Produce

Now let’s take a look at animal produce like meat, eggs, and dairy. Srednicka-Tober et al. conducted a systematic review and meta-analysis comparing conventional milk and dairy products. They found that organic milk contained higher concentrations of omega-3 polyunsaturated fats. However, iodine and selenium were significantly higher in conventional milk. Overall the compositional differences in omega-3 fay advices were modest and unlikely to be nutritionally relevant. The primary reason for the difference in milk was because organic cows were grazing more. More fresh grass to munch on leads to more omega-3 fatty acids. This isn’t an organic-only phenomenon, it’s just that conventional cows are typically not grazed like organic cows. Ultimately, it doesn’t look like grazing (compared to grass silage feed or no grazing) results in higher amounts of unsaturated fat, protein, and the carotenoid lutein.

What about meat? An overall analysis detected higher concentrations of both omega-3 and omega-6 fatty acids in organic meat, overall higher polyunsaturated fat content, lower monounsaturated fat content, and similar saturated fat content. Interestingly, higher polyunsaturated fat concentrations were found in chicken and pork, but not beef (or lamb or goat in case you were wondering). Saturated fat was lower in organic chicken, but no other meat type. The magnitude of difference was small and the body of evidence included in the analysis was weak and inconsistent.

The overall conclusion for animal produce, including milk, meat, and eggs, appears to indicate higher levels of polyunsaturated fat (especially omega-3 fatty acids) in organic products. However, the total body of evidence for meats is inconsistent, and for most nutrients, doesn’t show nutritionally meaningful differences.

Takeaways

• Organic crops may yield higher levels of polyphenols, but evidence is inconsistent with specific nutrients
• Organic animal products (meat, eggs, dairy) appear to have higher levels of polyunsaturated fat, but these levels are unlikely to be nutritionally relevant in a total diet
• The overall weight of data does not emphatically support a unique health benefit of organic product over and above what could be gained from eating more fruits and veggies

About Dr. A’nna

Dr. A’nna is on a mission to help athletes better unstained and fuel their body so they can achieve what they never thought was possible. As the only combined PhD/Registered Dietitian in the world with all Ivy League degrees specializing in sports performance nutrition, she works with athletes, teams, scientists and innovators to help progress sports nutrition research. You can reach her at anna@drannaroby.com.