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METABOLIC STUDIES IN CHILDREN

After the extensive testing carried out with experimental animals, it was concluded that the product was safe to be fed to children. The studies carried out were designed to establish the protein quality of experimental lots of cottonseed flour with free gossypol levels at the accepted level of 0.055 per cent or below (5)

Gossypol balance studies were also performed, since the batches of cottonseed flour used in the preparation of the mixture came from different oil-extraction processes with varying levels of free gossypol at or below the 0.055 upper limit. In the various studies conducted, different batches of cottonseed flour were used to prepare the high-protein food. Protein intake was usually about 3.0 g/kg/day, with energy intake at 100 car/kg/day. In all tests the children received a multi-vitamin and mineral capsule. Faecal collections were carried out daily and pooled every six days to run the analyses. An example with three children about 11 years of age is shown in table 11. The variability for both free and total gossypol excretion is quite high, making the interpretation of the results difficult. The relatively low protein digestibility could account for the large excretion values. Another example with six children is shown in table 12. A third example is shown in table 13 in which the same six children were fed a formula made with a cottonseed flour containing higher gossypol levels. As in the animal studies, variability in free gossypol excretion was quite high, but more consistent for total than free gossypol.

The gossypol balance studies conducted with the experimental animals and children are summarized in table 14. The method used to obtain the samples is also shown.

TABLE 14. Summary of Gossypol Balance Studies in Children and in Experimental Animals

TABLE 15. Effects Common to Both Gossypol Toxicity and Lysine Deficiency

FIG. 2. Possible Balance of Free and Total Gossypol in the Small Intestine

FIG. 3. Sequence of Events That May Explain Gossypol Toxicity

The data indicate that balance methods involving faecal collections show more erratic results than if the samples analysed are collected from the intestinal tract. The higher free gossypol values could result from a lack of sensitivity of the usual gossypol analytical technique used, to hydrolysis of bound gossypol, or both. It is also possible that the absorbed free gossypol is excreted back into the intestine, as suggested in figure 2. However, no evidence has been obtained to confirm whether or not the so-called bound gossypol is partially hydrolysed to yield the high levels of gossypol found in faeces. Such studies would now be done with labelled gossypol, as in more recent studies from other laboratories (9 - 11).

CONCLUSIONS

From the research results of various investigators as well as those from our laboratories, we propose that gossypol toxicity, or its anti-physiological effects, could be explained on the basis of its activity at the metabolic level. One aspect that has attracted our attention is the effects of Iysine deficiency. Some of these findings are listed in table 15, and to us the more significant effect is that of gossypol reacting with iron and basic amino acids, such as Iysine and perhaps arginine, at the metabolic level. Using the published information, we propose a working scheme of gossypol anti-physiological action summarized in figure 3. Information on some of the parameters shown is available, but more information should be obtained. It is possible that gossypol, when ingested at relatively high levels, may interfere with reproduction through its action of binding essential nutrients such as the basic amino acids or minerals.

Finally, we recommended that people consume about 75 g of Vegetable Protein Mixture 9 per day. Such high intakes are rare, but even if consumed, free gossypol intake would be only about 15 mg/day. It was demonstrated, however, that cooking will decrease free gossypol levels by about 50 per cent; therefore, total intake would be 7.5 mg at the highest. Since the digestibility of the protein in the food is about 72 per cent, some of the free gossypol will be eliminated in faeces, leaving only small amounts to be absorbed (5.4 mg), which are probably efficiently metabolized by animals and human subjects. We therefore feel that the consumption of a food product containing cottonseed flour is not harmful to the health of individuals, nor will it interfere with physiological functions.

REFERENCES

1. R, Bressani, L.G. Elias, A. Aquirre, and N.S. Scrimshaw, "All-Vegetable Protein Mixtures for Human Feeding. lilt The development of INCAP Vegetable Mixture Nine," J. Nutr.,., 74: 201 208 (1961).

2. N.S. Scrimshaw, M. Béhar, D. Wilson, R, De Leon, and R. Bressani, "The Development of INCAP Vegetable Mixtures III. Clinical and Field Trials," in Progress in Meeting Protein Needs of Infants and Preschool Children, National Academy of Sciences- National Research Council Publication no. 843, (Washington, D.C., 1961).

3. R. Bressani, L.G. Elías, J.E. graham, and M. Erales, "Long" Term Rat Feeding Studies with Vegetable Mixtures Containing Cottonseed Flour Produced by Different Methods," .J .Agric. Food Chem., 17: 1135 - 1138 (1969).

4. J.E. Graham, A.G. Canas, and R. Bressani, "Absorción de Gosipol en Ratas y Cerdos," Arch. Latinoamer. Nutr., 21: 449 471 (1971).

5. R. Bressani, L.G. Elías, and J.E. graham, "Cottonseed Protein in Human Foods," in World Protein Resources, Advances in Chemistry Series, No. 57 (American Chemical Society, Washington, D.C., 1966), pp. 75 - 1 00.

6. F.E. Viteri and R. Bressani, "The Quality of New Sources of Protein and Their Suitability for Weanling and Young Children," Bull. Wld Hlth. Org., 46: 827 - 843 (1972).

7. R. Bressani, L.G. Elías, R. Jarquín, and J. E. graham, "All Vegetable Mixtures for Human Feeding XIII. Effect of cooking mixtures containing cottonseed flour on free gossypol content," food Technol., 18: 95 - 99 (1964).

8. R. Bressani, J.E. graham, L.G. Elías, and R. Jarquín, "Technological Aspects of INCAP Vegetable Mixture Nine," in: Proceedings of a Conference on Cottonseed Protein Concentrates, New Orleans, La., 15 - 17 Jan. 1964, (US Department of Agriculture, Washington, D.C.), pp. 112 - 133.

9. M.B. Abdou-Donia and J.W. Dieckert, "Metabolic Fate of Gossypol: The Metabolism of 14C Gossypol in Swine," Toxicology and Applied Pharmacology, 31: 32 - 46 (1975).

10. M.B. Abdou-Donia and J.W. Dieckert, "Urinary and Biliary Excretion of 14C-Gossypol in Swine," J. of Nutrition, 104: 754 760 (1974).

11. C. L. Skutches and F.H. Smith, "Metabolism of Gossypol from ¹⁴C- and Carbosyl- ¹⁴C- Labelled Sodium Acetate in Rats," J. Amer. Oil Chemists' Soc., 51: 414 - 415 (1974).

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