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What do the Studies have to say: Nutrients Numerous studies have been conducted to compare organic food to conventional food in terms of nutritional content. Here is a summary of what they have to say: Worthington, Virginia. "Nutritional Quality of Organic versus Conventional Fruits, Vegetables, and Grains," The Journal of Alternative and Complementary Medicine, 2001. 7(2): 161-173. This is a review article in which the results of 41 studies were analyzed. Results showed that organic foods contain more vitamin C, iron, magnesium, and phosphorus than conventional food. In addition, organic foods contain less nitrates and and less protein, but more high quality protein than conventional foods. The review confined results to the five most frequently studied vegetables (lettuce, spinach, carrot, potato, and cabbage), and the 12 most frequently studied nutrients (calcium, copper, iron, magnesium, manganese, phosphorus, potassium, sodium, zinc, beta carotene, vitamin C, and nitrates. The only significant differences isolated were vitamin C, iron, magnesium, phosphorus, and nitrates. Vitamin C: on average, organic foods contained 27% more than conventional foods. Iron: on average organic foods contained 21% more than conventional foods. Magnesium: on average organic foods contained 29% more than conventional foods. Phosphorus: on average organic foods contained 14% more than conventional foods. Nitrates: on average organic foods contained 15% less than conventional foods. Some interesting connections: Organic foods typically contain less nitrates because they are not grown with nitrogen-containing fertilizer. In conventional methods, nitrogen is added to fertilizer to be made available to plants for protein production. Various gut bacteria can convert nitrates to nitrites and then into nitrosamines. Nitrosamines have been shown to be carcinogenic in some cases and have a special association with gastric carcinoma. The higher levels of vitamin C observed in organic foods is also related to nitrogen: when plants are presented with high nitrogen loads, they produce more protein and less carbohydrate. Vitamin C (ascorbic acid) is made from carbohydrates. Therefore, decreasing carbohydrate availability leads to decreased vitamin C in conventional foods. Study Limitations: it is interesting to point out that, in this review, any of the 41 studies which showed no significant difference between conventional foods and organic foods were excluded. Additionally, the author points out that while organic versus conventional foods were compared in the same year, it is impossible to make the growing conditions exactly identical in terms of climate, rainfall, soil quality, etc. Magkos, F., Arvaniti, F., & Zampelas, A. "Organic food: nutritious food, or food for thought? A review of the evidence." International Journal of Food Sciences and Nutrition, 2003. 54(5): 357-371. Another review article, this is an excellent resource with comprehensive comparisons of organic to conventional foods. Results showed that: Vegetable group: Protein: organic foods have less total protein (owing to the fact that organic techniques do not use nitrogen containing fertilizers), but a higher concentration of essential amino acids. The authors conclude that neither of these facts are likely to have any CLINICAL significance because so little dietary protein comes from the vegetable group anyway. Vitamins: no clear differences can be seen between organic and conventional food in terms of vitamins A, B1(thiamine), and B2 (riboflavin). There is a trend for higher vitamin C content in organic foods, but the authors concluded that no generalized statements could be made. Minerals: these authors conclude that while some studies did show higher amounts of iron, calcium, phosphorus, and magnesium, the majority of studies show no significant difference between food groups. Carbohydrate group (cereals and legumes): protein conclusions were similar to those noted above. Interestingly, in terms of vitamins and minerals, studies gave varied results. Sometimes organic foods had higher vitamin content, sometimes they were lower, and sometimes they were the same as conventional foods. *More interestingly, the results seemed to vary with the PART of the cereal that was studied (hull, seed, germ) which emphasizes how important study design ends up being in these comparisons. Animal Studies: This review article also highlighted some very fascinating results from studies examining outcomes for animals raised on exclusively organic versus conventional diets. Some key differences: -weight gain was greater in organically fed rats, mortality was lower at 9 weeks, and the incidence of degenerative diseases was lower. -lower mortality rates have also been observed in organically fed rabbits. -second and third generation rabbits from organically fed parents exhibited higher birth rates and more viable embryos in sacrificed females. Additionally, infectious illnesses were less frequent in second generation organically fed animals. -numerous studies have also shown that animals prefer organic foods or feed over conventional foods. This observation has been made even when both food sources, when examined, met the physiologic demands of the animals. Such observations have led researchers to conclude that some other parameter, such as taste, must drive the animals' feeding behavior since the foods are nutritionally equal. **It is EXTREMELY important to note that these animal studies are included only to point out some very fascinating observations. By no means and in no case should these results be generalized to human populations. |
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Creighton University School of Medicine: Complementary and Alternative Medicine |