Q: Hi, the Paleo Diet makes a lot of sense to me and I very much appreciate the research that's gone into it. However, am I right in thinking that any diet we are adapted to may nevertheless not be an ideal diet? We adapted to a diet that enabled us to be healthy enough to live long enough to reproduce healthy enough offspring.
If I understand correctly, couldn't certain foods could make that basic diet even healthier? For example, I have The Paleo Diet for Atheletes out from the library right now and I see that you believe that the life of an athlete requires departure from a strict paleolithic diet. Couldn't properly treated grains and legumes be beneficial additions to the diet? (i.e. soaked/sprouted to reduce/eliminate anti-nutrients?)
I am waiting to receive The Paleo Diet from the library (I'm on a long waiting list, which is good news I guess!) so maybe you address this issue in the book, in which case, I apologise. But if not, I would appreciate knowing your views on soaking/sprouting grains and legumes, and the reasons behind those views.
Thanks so much,
Zena
A: Dear Zena, first of all - thanks for supporting our work.
Lectins, one of the known antinutrients in cereal grains and legumes1, have been demonstrated to exert several deleterious effects upon human physiology1, (especially for those with autoimmune diseases) by increasing intestinal permeability2. Their function is to protect the plant against attacks by plant-eating animals by using several toxic substances, such as lectins3. There is a growing body of evidence showing that both the root and the sprout of wheat kernels have significant amounts of wheat germ agglutinin (WGA), one of the most studied lectins. Indeed, WGA originates in the wheat kernel, especially during germination and growth4, and the highest concentrations are found in young plant roots, seeds, and sprouts.
Lectins are resistant to digestive enzymes, and are found intact in peripheral circulation, as shown by Wang et al (1998)5. Furthermore, they are deposited in the internal organs6.
As stated by Pusztai et al7, lectins are heat stable, and normal cooking does not completely eliminate these toxic compounds unless they are pressur cooked8-11. The best way to reduce lectins' adverse health effects is to limit their intake.
In addition, saponins - another type of toxic/antinutritive compound - exist in legume sprouts. Saponins have been shown to affect the gut barrier and by extension immune system function12. They may also increase the risk of autoimmune diseases in genetically susceptible individuals13. Soaking, sprouting or cooking legumes, does not reduce their saponin content14, 15.
In addition, a peptide fraction from gluten proteins called gliadin is found in wheat. Gliadin is resistant to digestive enzyme degradation16, arrives intact when it comes into contact with intestinal epithelial cells17, and increases intestinal permeability. Increased intestinal permeability may be at the root of autoimmune diseases such as Celiac Disease and Type 1 Diabetes13.
Phytate, the main form of phosphorus storage in many plants (especially bran and seeds) is classified as an antinutrient because is a chelator of iron, magnesium, calcium and zinc1. Phytate ingestion inhibits the intestinal absorption of those minerals. Phosphorus from phytate is unavailable to humans, as we do not produce the phytase enzyme necessary to break down phytate - unlike ruminants, who do produce phytase, and are able to digest phytate18. Yeast fermentation in bread reduces phytate content19. Furthermore, addition of ascorbic acid counteracts the inhibitory effects of phytate upon iron absorption20. Soaking and fermentation reduces the phytate content of grains and legumes as indicated in several studies21, 22, 23, 24.
Having said that, Dr. Cordain in his first book talks about the 85:15 rule, where he explains that 85% of caloric intake from modern paleolithic-like foods is still more healthy than the typical western diet, where more than 70% of caloric intake comes from foods introduced in the human food chain after the agricultural revolution25.
The bottom line is that our metabolism is perfectly adapted to the nutrition that shaped our genome during million of years of evolution. Therefore, any nutrient introduced after the agricultural revolution may not be compatible with our ancient genome. We believe that anyone engaged in athletic activities could do very well on a diet based on 85% paleolithic nutrients, which are preferable to the nutrients found in the typical western diet.
I hope this is helpful.
Maelán Fontes
References:
1. Cordain L. Cereal Grains: Humanity’s Double-Edged Sword. World Rev Nutr Diet. Basel, Karger, 1999, vol 84, pp 19–73.
2. Cordain L. et al. Modulation of immune function by dietary lectins in rheumatoid arthritis. British Journal of Nutrition (2000), 83, 207–217.
3. Chrispeels, M.J. & Raikel, N.V. (1991) Lectins, lectin genes, and their role in plant defense. Plant Cell 3, 1-9.
4. Miller, R., & Bowles, D. (1982). A comparative study of the localization of wheat-germ agglutinin and its potential receptors in wheat grains. Biochem. J., 206, 571-576.
5. Wang Q, Yu LG, Campbell BJ, Milton JD, Rhodes, JM. Identification of intact peanut lectin in peripheral venous blood. Lancet 1998;352:1831-32.
6. Caron, M. & Steve, A.P. (2000) Lectins and Pathology, Taylor & Francis, London.
7. Pusztai A and Grant G. Assessment of lectin inactivation by heat and digestion. From Methods in Molecular Medicine. Vol 9 Lectin methods and protocols. Edited by J M Rhodes and J D Milton Humana Press Inc. Totowa, NJ.
8. Grant G, More LJ, McKenzie NH, Pusztai A. The effect of heating on the haemagglutinating activity and nutritional properties of bean (Phaseolus vulgaris) seeds. J Sci Food Agric 1982;33: 1324-1326.
9. Boufassa C, Lafont J, Rouanet J M, Besancon P 1986 Thermal inactivation of lectins (PHA)isolated from Phaseolus vulgaris. Food Chem 20 295-304.
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12. Patel B, Rober S, Sporns P, et al. potato glycoalkaloid adversely affect intestinal permeabiliry and aggravate inflammatory bowel disease.
13. Visser J, Rozing J, Sapone A et al. Tight junctions, Intestinal permeability and Autoimmunity. Ann. N. Y. Acad. Sci. 1165: 195-205 (2009).
14. Ruiz RG, Price K, Rose M, Rhodes M, Fenwick R. A preliminary study on the effect of germination on saponin content and composition of lentils and chickpeas. Z Lebensm Unters Forsch 1996;203:366-369.
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18. non-celiac intestinal mucosa and intestinal cell lines. Scandinavian Journal of Gastroenterology, 2006; 41:408/419.
19. Klopfenstein, TJ et al. "Animal Diet Modification to Decrease the Potential for Nitrogen and Phosphorus Pollution". Council for Agricultural Science and Technology 21.
20. Reinhold JG. Phytate destruction by yeast fermentation in whole wheat meals. J Am Diet Assoc 1975;66:38-41.
21. Hallberg L, Brune M, Rossander L. Iron absorption in man: ascorbic acid and dose-dependent inhibition by phytate. Am J Clin Nutr 1989;49:140-4.
22. Chen LH, Pan SH. Decrease of phytates during germination of pea seeds (Pisium Sativa). Nutr Rept Int. 1977;16: 125-131.
23. Walker KA. Changes in phytic acid and phytase during early development of phaseoleus vulgaris beans. Planta 1974;116:91-98
24. Bain, J. M., Murcer, F. V.: Changes in phytic acid and acid-soluble phosphorus in maturing pinto beans. J. Sci. Fd. Agric. 20, 82–84 (1966).
25. Jennings, A. C., Morton, R. K.: Changes in nucleic acids and other phosphorus-containing compounds of developing wheat grain. Aust. J. Biol Sci. 16, 332–341 (1963b).
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