Organic Food: Is it More Nutritious?

Is organically grown food more nutritious?

This is not a simple question to answer. To start with, studies into the difference between organic foods and conventionally produce generally have not been comprehensive or sufficiently large to be readily applicable general populations. Secondly, is difficult to conduct and interpret agricultural research investigating nutrient content. Many factors that influence the nutrient content of plants, including sunlight, temperature and rainfall, vary from year to year. Storage and shipping can cause further changes in the nutrient content of a crop. For these reasons, it is difficult both to plan effective studies and to make sense of the results. This also makes it difficult to compare the results of different studies. Finally, a large proportion of the current scientific literature is outdated and was not performed according to modern standards. For example, it is common that older studies do not include a rigorous statistical analysis.

According to Dr Worthington (Alternative Therapies, 4, 1998, 58- 69), there are more than 30 studies comparing the nutrient content of organic crops and those produced conventionally with chemical fertilizers and pesticides. In these studies, various individual nutrients in individual crops were compared, such as zinc in organic versus conventional carrots, or vitamin C in organic versus conventional broccoli. Overall, organic crops had an equal or higher nutrient content about 85% of the time. Over a number of nutrients in the crops that have been studied, the average organic crop has approximately 10-20 percent higher nutrient levels than a comparable conventional crop. In relation to toxic substances, there are not many studies except for nitrates, but it appears that on average, the organic crop has at least 10-20 percent less toxics.

While the data seems to be favourable for organics, there is simply too little data for most individual nutrients to say anything certain. Except for vitamin C, nitrates and protein quality, there is insufficient evidence to suggest that organic crops are superior to conventional.

There are known mechanisms and scientific explanations for the observed differences in nutrient levels. A portion of the difference is due to effects of fertiliser on soil dynamics and plant physiology. For example, the excessive quantities of nitrogen presented to the plant by chemical conventional fertilizers cause the plant to produce more nitrates, less vitamin C and a poorer quality protein. Similarly, conventional potassium fertilizers make soil magnesium less available to plants so that levels of this nutrient are lower in potassium fertilized plants.

In addition, pesticides and herbicides are known to affect plant composition. Herbicides are particularly nasty in that they kill plants by altering their production of key compounds, such as beta-carotene, tocopherols and amino acids, all of which have nutritional significance. Although food crops are not killed by herbicides, the nutritional composition of these crops may still be altered. For example, the few studies that examined the effects of herbicides on protein, all showed a decline in protein quality with herbicide usage.

While the nutrient content data is interesting, it does not shed light on issues surrounding the health of people and animals that consume organic or conventional crops:

There are 14 animal studies that have been performed over the last 70 years. In ten of these, the organically fed animals fared better; in one, the animals fed organic feed came in second among several chemically fertilized feeds; and three studies showed no difference. The positive effects are most striking in sick or otherwise vulnerable animals, such as newborns, and in sensitive areas of reproduction, such as sperm motility. It is particularly interesting to see that the fertility of animals fed fodder grown with chemical fertilizers and pesticides declined over several generations. -Worthington, 1998

Where does this leave us? One can see a pattern of better nutrient composition in organic food, better health in animals consuming organic food and the existence of known mechanisms explaining observed differences between organic and conventional crops. Biodynamic crops performed extremely well on the most important measure, the health of consumers. Whatever problems there may be with the quantity or quality of existing studies, the body of evidence, at a minimum, provides strong indications that organic crops are more nutritious.



Average difference in nutrient levels between biodynamic, organic and overall organic crops, compared to similar conventional crops

                                          Biodynamic             Organic              Overall
Nutrient                            % difference      % difference         % difference

Vitamin C                     +47.6%             +11.9%                +22.7%
Iron                               +33.9%             +15.6%                +17.2%
Calcium                       +07.4%             +38.4%                 +30.8%
Phosphorus                  +06.6%             +14.3%                 +12.5%
Sodium                        +20.3%             +19.3%                +19.6%
Potassium                    +07.9%             +16.2%                +14.1%
Magnesium                  +13.2%             +28.3%                +24.4%
Beta-carotene              +14.0%             -09.2%                 -00.3%
Nitrates                        -49.8%             -30.9%                 -33.9%


From a systematic literature review article entitled “Effect of Agricultural Methods on Nutritional Quality: A Comparison of Organic with Conventional Crops” by Dr. V. Worthington, which appeared in Alternative Therapies, Volume 4, 1998, pages 58-69.