Article : Nutrition & Biodynamics

Virginia Wilson "Ginger" Worthington, a nutritionist whose research suggested that organic produce is more nutritious than conventional food, died Nov. 27 2006 of breast cancer at her home in Washington. She was aged 60.

Beginning in 1998, Dr. Worthington published several studies that proclaimed the nutritional superiority of organically produced foods. Her best-known study, which appeared in the Journal of Alternative and Complementary Medicine in 2001, examined 41 other research papers.

First published in: THE JOURNAL OF ALTERNATIVE AND COMPLEMENTARY MEDICINE Volume 7, Number 2, 2001 PP. 161—173 Mary Ann Liebert, Inc.

Nutrition and Biodynamics:
Evidence for the Nutritional Superiority of Organic Crops

Biodynamics v.224, Jul/Aug99

Virginia Worthington / The Co-op Connection Nov01

Virginia Worthington MS, ScD, CNS

While it is generally acknowledged that pesticide residues in food and drinking water may be a bad thing, the conventional wisdom still holds that organic food is no more nutritious than conventionally grown food. A stunning lack of interest on the part of government and university researchers is in large part to blame for this situation. What is behind claims about the nutritiousness of organic food and how does biodynamic food stack up against the rest of the pack? Let's take a look at the evidence.

There have not been a huge number of researchers that have even considered the influence that agriculture methods might have on human or animal nutrition. Nevertheless, there have been at least thirty-five studies comparing the nutrient levels of organic and conventional crops. Few of these studies are directly comparable. Some look at only fertilizers and others at farming systems such as biodynamics; some examine freshly picked produce at the farm gate while others look at crops that have been in storage or have been shipped to market. Moreover, taken individually, few of the studies show conclusive evidence one way or the other. As a consequence, it is easy to walk away thinking that there is no significant difference.

However, when the nutritional comparisons are piled up together and we ask the right questions, a different picture emerges which suggests that organically grown crops are more nutritious. In the following sections, we will ask a few of these questions with regard to the body of published comparisons, and along the way see how well biodynamic crops compare both to conventional and to other organic crops.

How often is organic better?
This first question deals with how much of the time organic crops have a better nutrient content than similar conventional crops. This is an important questions because it tells how likely a consumer would be to come across an organic food item with higher nutrient levels or lower levels of toxic substances. A rough answer to this question can be obtained by looking at the numbers in the published studies, and sorting the comparisons by outcome - organic with a higher nutrient content (or lower for toxics), conventional higher, or both exactly the same.

Figure 1 shows the results of this process: the organic crop has the higher nutrient level or lower toxic level in 56 percent of the comparisons while the conventional crop was better only 37 percent of the time. For biodynamic crops, the numbers are similar with the biodynamic crop having a better nutrient content 59 percent of the time and the conventional crop 27 percent of the time. These results are significant since the organic crop has the better nutrient content the majority of the time. Overall this pattern suggests that any nutritional benefits that organic food might offer would occur often enough to be useful to a consumer and that biodynamics has a slight edge in that regard.

Figure 1. Organic versus conventional
Percent of 1230 published comparisons where
nutrient levels are better, worse or the same

How much better is organic?
The second question asks how much more of each nutrient is there on average for organic crops versus conventional crops. The average percent more or less for some nutrients is shown in Table 1 below. 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. For 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.

How do biodynamic crops compare to other organic crops in terms of nutrient levels? There are too few biodynamic studies to answer this question in any meaningful way for most nutrients. Nonetheless, we can do a preliminary evaluation. Table 1 shows the average difference in nutrient levels for both biodynamic and other organic crops. Of the nutrients shown in Table 1, only vitamin C has been studied to any extent in biodynamic crops, and vitamin C levels appear to be higher in biodynamic crops compared to other organic crops. Otherwise, from the small quantity of existing data, biodynamic crops appear to be reasonably similar to other organic crops.

We have seen now from this analysis that organic crops have higher levels of nutrients the majority of the time. Still, it is easy to dismiss all of this as insignificant since the absolute quantities of nutrients are small. For example, if there is 47 percent more vitamin C, for most foods that amounts to no more than a few milligrams. Are these small differences of any consequence? A few years ago it would have been easy to brush them aside, but it is now known that there are many nutrient interactions and that small differences do matter.

For example, an increase in vitamin C increases the effect of vitamin E, folic acid and iron. The increase in vitamin E then increases the effect of selenium and vitamin A. Vitamin A further increases the effect of iron, and so on. Because of these interactions, small increases (or equally decreases of toxic substances), over the many nutrients in a food, can have a much bigger effect than would be expected from looking at the individual nutrient levels. Nutritionally speaking, the whole is greater than the sum of the parts. And small differences in nutrient levels can matter a lot.

Table 1. Average difference in nutrient levels
*Biodynamic, non-biodynamic and all organic crops compared to similar conventional crops

               Biodynamic     Other organic   All organic
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%

*All nutrients that have been measured in biodynamic crops are included.

Does organic food make you healthier?
This brings us to the most relevant question: what happens to the health of animals and humans eating organic foods? There are no human studies to look at, but there are reports of positive health effects from consumption of organic foods. One published report tells of the improved health of students at a boarding school that began serving organically fertilized fruits and vegetables. Other reports come from doctors, administering alternative cancer treatments, who have observed that a completely organic diet is essential for a successful outcome.

As for formal investigations, there are fourteen animal studies comparing organic with conventional feed. Biodynamic studies are shown in Table 2 and other organic studies in Table 3. What is striking about the studies as a whole is that there are eight studies where the organically fed animals performed significantly better and no studies where the conventionally fed animals performed much better. In addition, the three studies showing no difference had methodological problems that made them unlikely to find one. In these studies, animals were either supplemented with vitamin A or fed high vitamin A feed and then judged on outcomes which would be affected by this vitamin.

The positive studies showed that organically fed animals had less illness, better recovery from illness, better testes condition and greater sperm motility in males, greater egg production in females, better fertility, fewer stillbirths and perinatal deaths, and better survival of young. These outcomes, reproduction and incidence and recovery from illness, are sensitive indicators of health status, and should be given appropriate weight. Taking all of this into account, the available data is very strong with regard to the health benefits of organic feed.

Of the strongly positive studies, the majority used biodynamic feed, and all of the biodynamically fed animals performed excellently compared to conventionally fed animals. All of the biodynamic studies were clearly positive. Non-biodynamic studies, on the other hand, showed more mixed results, with some studies being extremely positive and others showing a less clear cut benefit. Altogether, these results suggest that while a number of organic systems may be capable of producing positive results, biodynamics at the very least provides a model for a healthy agricultural system.

Table 2. Animal studies comparing biodynamic with conventional feed

Study                           Outcome                                         
Pfeiffer, 1938 earlier (166 vs 181 days of age) & greater
cited in Linder, 1973 egg production (192 vs 150 eggs per hen) in
chickens fed biodynamic versus conventionally
fertilized grain. Spoilage of eggs after
6 months was 27% for biodynamic eggs versus
60% for conventional eggs
lower mortality (9% vs 17%) in weanlings fed
biodynamic wheat versus conventionally grown wheat

Aehnelt & Hahn, 1973 greater number of eggs (8.6 vs 1.8 & 0) and higher
fertilization rate (93.1% vs 0% & 0%) in rabbits
fed biodynamic versus conventionally fertilized feed

Staiger, 1986 fertility rate of rabbits remained constant over 3
cited in Vogtmann, 1988 generations with biodynamic feed and declined with
conventionally grown feed

Plochberger, 1989 better weight gain after coccidial illness & fewer
incidents of illness in chickens fed biodynamic feed;
significantly higher egg weight and yolk weight in
chickens fed biodynamic feed compared to birds fed
chemically fertilized feed

Velimirov et al, 1992 fewer stillbirths and perinatal deaths in first litters
and better weight maintenance in lactating female rats
fed biodynamic feed versus conventional feed

Table 3. Animal studies comparing non-biodynamic organic with conventional feed

Study                           Outcome                                    
McCarrison, 1926 less weight loss (22.4% vs. 37.4%) & longer
survival (50 vs 33 days) in birds with polyneuritis
fed a manure fertilized millet supplement versus birds
fed a chemically fertilized millet supplement
higher weight gain (77.7% vs 51.4%) in young rats fed
manure- versus chemically-fertilized wheat

Rowlands & Wilkinson, 1930 greater weight gain in vitamin B deficient rats fed a
manure fertilized seed supplement versus rats fed a
chemically fertilized seed supplement

Harris, 1934 duration of cure for bradycardia in rats was 6, 5 and 4 days
when fed grain fertilized with ammonium sulphate, manure,
and complete chemical fertilizer

Leong, 1939 duration of cure for bradycardia was similar or longer for
rats fed wheat (5.0 vs 5.4, 5.2, 5.1 days) or
barley (8.1 vs 5.3, 4.8, 4.7 days) from fields treated
with manure versus complete chemical fertilizer,
ammonium sulphate or both

Swanson, 1940 no difference in growth in vitamin A depleted rats
supplemented with sweet potatoes fertilized with manure,
muriate of potash, nitrate of soda or superphosphate

Miller & Dema, 1958 no difference in reproduction in rats

Scott et al, 1960 less testes degeneration & similar reproductive performance
in mice fed manure-fertilized wheat versus conventional feed

Aehnelt & Hahn, 1973 reduced sperm motility in bulls transferred from organic to
conventional fodder; motility restored when organic fodder resumed

Gottschewski, 1975 mortality of newborn rabbits was 27% for animals fed organic
cited in Vogtmann, 1988 feed versus 51% for those fed conventional feed and 50% for those
fed commercial pellets

McSheehy, 1977 no difference in reproduction in mice
Is there any more evidence?
A final point is that there are known mechanisms and scientific explanations for the observed differences in nutrient levels. A portion of the difference is due to effects of fertilizer. The soil dynamics and plant physiology that would produce some of the observed nutritional differences are known. 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 are known to affect plant composition, and there are a few studies showing nutritional effects. 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.

A complete exposition of the science behind the nutritional effects of agricultural chemicals is well beyond the scope of this article, but nonetheless, the fact that these chemicals are known to affect the nutrient composition of plants should not be forgotten.

Where does this leave us? We have seen a pattern of better nutrient composition in organic crops, 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.

Appendix: analytical methods
This analysis used all studies, available to the author, comparing crops produced with organic fertilizer or by organic farming systems to conventional fertilizers or systems (see sections 1and 2 of the references). Studies of research plots, pot studies, farm gate produce, stored produce and produce purchased at markets were all included. The reason for this is that there are insufficient data of any one type to draw meaningful conclusions. Consequently, all the data was considered. Fertilizer studies were used because differences in fertility management are historically the most fundamental difference between organic and conventional agriculture. In addition, fertilizer effects are often ignored in the furor over the toxic effects of pesticides.

For purposes of this analysis, a single comparison consisted of a single nutrient in a single organic vegetable crop grown in one growing season compared to the same nutrient in the same conventionally grown crop grown in the same season. A few studies reported pooled comparisons that included more than one year or more than one crop. These comparisons were included in the analysis when single comparisons were not available.

To produce Figure 1, all available published comparisons (n=1230) were sorted by outcome. The three outcome categories are:

  1. organic with a higher nutrient level or a lower level of a toxic substance
  2. conventional with a higher nutrient level or a lower level of a toxic substance
  3. both the same.
This sorting was done by the numerical values or by the stated outcome for studies where no numbers were published. Statistical significance of differences was not considered.

The percentages in Table 1 use the conventional crops as the standard or 100% so that a difference of +10 means that organic crops have on average 110% of the conventional level for the same nutrient. Only studies that contained numerical values were used for this part of the analysis. The percentages were calculated by first calculating a percentage difference for each nutrient within a study. For each nutrient, the percentage differences by study were averaged. In a few cases, a study included both biodynamic and other organic comparisons. Separated averages were calculated for these groupings.

The number of studies and comparisons for each nutrient used in Table 1 is shown in Table A-1 below:

Table A-1. Number of studies and comparisons for nutritional factors classified by biodynamic or non-biodynamic status

              Non-biodynamic                Biodynamic            
No. No. No. No.
Nutrient of studies of comparisons of studies of comparisons

nitrates 16 144 3 27
beta-carotene 9 24 3 15
vitamin C 17 92 5 39
iron 14 77 1 7
magnesium 14 73 2 24
phosphorus 14 75 2 22
calcium 14 72 2 22
sodium 9 41 2 19
potassium 13 70 2 22

1. Nutrient levels in biodynamic crops

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Bessenich, F.. 1946. Regarding the vitamin content of vegetables. BIODYNAMICS 4:7-10.

Dlouhy, J. 1977. The quality of plant products under conventional and bio-dynamic management. BIODYNAMICS 124:28-32.

Hansen, H. 1981. Comparison of chemical composition and taste of biodynamically and conventionally grown vegetables. Qualitas Plantarum 30:203-211.

Linder, M.C. 1973. A review of the evidence for food quality differences in relation to fertilization of the soil with organic or mineral fertilizers. BIODYNAMICS 107:1-11.

Pettersson, B.D. 1983. A comparison between the conventional and biodynamic farming systems as indicated by yields and quality. In W. Lockeretz (ed). Environmentally Sound Agriculture. Praeger. New York. pp.87-94.

Pfeiffer, E. 1951. The experimental garden of 1950. BIODYNAMICS 9:11-12.

Reinken, G. 1984. Six years of biodynamic growing of vegetables and apples in comparison with conventional farm management. In H. Vogtmann, E. Boehncke, I. Fricke (Eds.) The Importance of Biological Agriculture in a World of Diminishing Resources. Verlagsgruppe Weiland. Witzenhausen. pp. 161-174.

Schuphan, W. 1974. Nutritional value of crops as influenced by organic and inorganic fertilizer treatments. Qualitas Plantarum 23:333-358.

2. Nutrient levels in other organic crops

Barker, A.V.. 1975. Organic vs. inorganic nutrition and horticultural crop quality. HortScience 10:50-53.

Blanc, D., G. Gilly, J. Leclerc, and J Causeret. 1984. Appréciation de l'effet … long terme de la nature organique ou minérale de la fertilisation sur la composition de laitue et de la pomme de terre. Sciences des Aliments 4:267-272.

Brandt, C.S. and K.C. Beeson. 1951. Influence of organic fertilization on certain nutritive constituents of crops. Soil Science 71:449-454.

Chang, P.T. and M. Salomon. 1978. Metals in grains sold under various labels - organic, natural and conventional. Journal of Food Quality 1:373-77.

Clarke, R.P. and S.B. Merrow. 1979. Nutrient composition of tomatoes homegrown under different cultural procedures. Ecology of Food and Nutrition 8:37-46.

Fischer, A. and C. Richter. 1984. Influence of organic and mineral fertilizers on yield and quality of potatoes. In H. Vogtmann, E. Boehncke and I. Fricke (eds.). The Importance of Biological Agriculture in a World of Diminishing Resources. Verlagsgruppe Weiland. Witzenhausen. pp. 236-248.

Harwood, R.R. 1984. Organic farming research at the Rodale research center. In D.M. Kral and S.L. Hawkins (eds.). Organic Farming: Current Technology and Its Role in a Sustainable Agriculture. American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. Madison, WI. pp. 1-17.

Kansal, B.D., B. Singh, K.L Bajaj and G. Kaur. 1981. Effect of different levels of nitrogen and farmyard manure on yield and quality of spinach (Spinacea oleracea L.). Qualitas Plantarum 31:163-170.

Lairon, D., H. Lafont, J. Leonardi, J.C. Hauton and P. Ribaud. 1982. Comparaison de l'intérêt nutritif de légumes produit par agriculture conventionelle ou biologique. Sciences des Aliments 2:203-205.

Lairon, D., E. Termine, S. Gautier, M. Trouilloud, H. Lafont, J.C.H. Houton. 1984a. Effects of organic and mineral fertilizations on the contents of vegetables in minerals, vitamin C and nitrates. In H. Vogtmann, E. Boehncke, I. Fricke (Eds.) The Importance of Biological Agriculture in a World of Diminishing Resources. Verlagsgruppe Weiland. Witzenhausen. pp. 249-60.

Lairon, D., N.Spitz, E. Termine, P. Ribaud, H. Lafont, J. Hauton. 1984b. Effect of organic and mineral nitrogen fertilization on yield and nutritive value of butterhead lettuce. Qualitas Plantarum 34:97-108.

LeClerc, J., M.L. Miller, E. Joliet and G. Rocquelin. 1991. Vitamin and mineral contents of carrot and celeriac grown under mineral or organic fertilization. Biological Agriculture and Horticulture 7:339-348.

Miller, D.S. and I.S. Dema. 1958. Nutritive value of wheat from the Rothamsted Broadbalk field. Proceedings of the Nutrition Society 17:xliv-xlv.

Nilsson, T. 1979. Yield, storage ability, quality and chemical composition of carrot, cabbage and leek at conventional and organic fertilizing. Acta Horticulturae 93:209-233.

Peavy, W.S. and J.K. Grieg. 1972. Organic and mineral fertilizers compared by yield, quality, and composition of spinach. Journal of the American Society of Horticultural Science 97:718-723.

Rauter and Wolkerstorfer reported in Lairons, D., E. Termine, H. LaFont. 1984c. Valeur nutritionelle comparee des legumes obtenu par les methods de l'agriculture biologique ou de l'agriculture conventionelle. Cah Nutr Diet 19:331-40.

Schudel, P., M. Eichenberger, F. Augustberger, R. Klay and H. Vogtmann. 1979. The influence of compost or NPK fertilization on yield, vitamin C and nitrate content of spinach and spinach beet. Schweizerische Landwirtschaftliche Forschung 18:337-349.

Shier, N.W., J. Kelman and J.W. Dunson. (1984). A comparison of crude protein, moisture, ash and crop yield between organic and conventionally grown wheat. Nutrition Reports International 30:71-76.

Smith, B. 1993. Organic foods vs. supermarket foods: element levels. Journal of Applied Nutrition 45:35-39.

Stopes, C., L. Woodward, G. Forde and H. Vogtmann. 1988. The nitrate content of vegetable and salad crops offered to the consumer as from "organic" or "conventional" production systems. Biological Agriculture and Horticulture 5:215-21.

Stopes, C., L. Woodward, G. Forde and H. Vogtmann. 1989. Effects of composted FYM and a compound fertilizer on yield and nitrate accumulation in 3 summer lettuce cultivars grown in an organic system. Agriculture Ecosystems and Environment 27:555-559.

Svec, L.V., C.A. Thoroughgood and H.C.S. Mok. 1976. Chemical evaluation of vegetables grown with conventional or organic soil amendments. Communications in Soil Science and Plant Analysis 7:213-228.

Termine, E., D. Lairon, B. Taupier-Letage, S. Gauthier, and J.C. Hauton. 1984. Influence des techniques de fertilisation organique et minérale sur la valeur nutritionnelle de légumes. Sciences des Aliments 4:273-277.

Termine, E., D. Lairon, B. Taupier-Letage, S. Gautier, R. Lafont, H. Lafont. 1987. Yield and content in nitrates, minerals and ascorbic acid of leeks and turnips grown under mineral or organic nitrogen fertilizations. Plant Foods for Human Nutrition 37:321-32.

Vogtmann, H. 1984. Organic farming practices and research in Europe. IN: Organic Farming: Current Technology and Its Role in a Sustainable Agriculture (Kral DM and Hawkins SL, eds.). American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. Madison, WI. pp. 19-36.

Vogtmann, H., A.T. Temperli, U. Kunsch, M. Eichenberger, and P. Ott. 1984. Accumulation of nitrates in leafy vegetables grown under contrasting agricultural systems. Biological Agriculture and Horticulture 2:51-68.

Warman, P.R. and K.A. Havard. 1996. Yield, vitamin and mineral contents of organically and conventionally grown carrots and cabbage. Agriculture, Ecosystems and Environment 61:155-62.

Warman, P.R. and K.A. Havard. 1996. Yield, vitamin and mineral content of four vegetables grown with either composted manure or conventional fertilizer. Journal of Vegetable Crop Production 2:13-25.

Wolfson, J.L. and G. Shearer. 1981. Amino acid composition of grain protein of maize grown with and without pesticides and standard commercial fertilizers. Agronomy Journal 73:611-613.

3. Animal studies

Aehnelt, E. and J. Hahn. 1978. Animal fertility: a possibility for biological quality assay of fodder and feeds. BIODYNAMICS 25:36-47.

Harris, L.J. 1934. Note on the vitamin B1 potency of wheat as influenced by soil treatment. Journal of Agricultural Science 24:410-415.

Leong, P.C. 1939. Effect of soil treatment on the vitamin B1 content of wheat and barley. Biochemical Journal 33:1397- 1399.

Linder, M.C. 1973. A review of the evidence for food quality differences in relation to fertilization of the soil with organic or mineral fertilizers. BIODYNAMICS 107:1-11.

McCarrison, R. 1926. The effect of manurial conditions on the nutritive and vitamin values of millet and wheat. Indian Journal of Medical Research 14:351-378.

McSheehy, T.W. 1977. Nutritive value of wheat grown under organic and chemical systems of farming. Qualitas Plantarum 27:113-123.

Miller, D.S. and I.S. Dema. 1958. Nutritive value of wheat from the Rothamsted Broadbalk field. Proceedings of the Nutrition Society 17:xliv-xlv.

Plochberger, K. 1989. Feeding experiments. A criterion for quality estimation of biologically and conventionally produced foods. Agriculture, Ecosystems and Environment 27:419-428.

Rowlands, M.J. and B. Wilkinson. 1930. Vitamin B content of grass reeds in relation to manures. Biochemical Journal 24:199-204.

Scott, P.P., J.P. Greaves and M.G. Scott. 1960. Reproduction in laboratory animals as a measure of the value of some natural and processed foods. Journal of Reproduction and Fertility 1:130-138.

Swanson P., G. Stevenson, E.S. Haber, and M. Nelson. 1940. Effect of fertilization treatment on vitamin A content of sweet potatoes. Food Research 5:431-8.

Velimirov, A., K. Plochberger, U. Huspeka and W. Schott. 1992. The influence of biologically and conventionally cultivated food on the fertility of rats. Biological Agriculture and Horticulture 8:325-337.

Vogtmann, H. 1988. From healthy soil to healthy food: an analysis of the quality of food produced under contrasting agricultural systems. Nutrition and Health 6:21-35.

4. Nutrition and health

Daldy, Y. 1940. Food production without artificial fertilizers. Nature 145:905-906.

Gerson M. 1990. A cancer therapy: results of fifty cases. Station Hill Press. Barrytown, N.Y.

National Research Council. 1981. The Health Effects of Nitrate, Nitrite and N-Nitroso Compounds. National Academy Press. Washington, D.C.

Shils, M.E., J.A. Olson, M. Shike. 1994. Modern Nutrition in Health and Disease. Williams & Wilkins. Baltimore, Md.

Vogtmann, H. 1985. The nitrate story - no end in sight. Nutrition and Health 3:217-239.

5. Fertilizers, pesticides and nutrient content

Berger, S. and K. Cwiek 1987. Nutritional importance of pesticides. In J.N. Hathcock (ed). Nutritional Toxicology. Academic Press, Inc. Orlando, FL. pp. 281-288.

Berger, S., B. Pardo, and J. Skowkowska-Zieleniewska. 1980. Nutritional implications of pesticides in foods. Bibliotheca Nutritio et Dieta 29:1-10.

Hannaway D.B., L.P. Bush, J.E. Leggett. 1980. Plant Nutrition: Magnesium and Hypomagnesemia in Animals. Bulletin 716. University of Kentucky, College of Agriculture. Lexington, KY.

Hippalgaonkar, K.V. 1985. Effect of simazine on protein content of trigonella. Indian Botanical Reporter 4:219.

Mondy, N.I. and C.B. Munshi. 1990. Effect of the herbicide metribuzin on the nitrogenous constituents of potatoes. Journal of Agricultural and Food Chemistry 38:636-639.

Mozafar, A. 1993. Nitrogen fertilizers and the amount of vitamins in plants: a review. Journal of Plant Nutrition 16:2479-2506.

Salunkhe, D.K., M.T. Wu and B. Singh. 1971. The nutritive composition of pea and sweet corn seeds as influenced by s-triazine compounds. Journal of the American Society of Horticultural Science 96:489-492.

Salunkhe, D.K. and B.B. Desai. 1988. Effects of agricultural practices, handling, processing, and storage on vegetables. In E. Karmas and R.S. Harris (eds.). Nutritional Evaluation of Food Processing. AVI Publishing Co. New York. pp.23-71.