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Lactulose in fat-free milk, rather than increased ghrelin and motilin level, might help for solving constipation: Author update
Nutrition 27 (2011) 731–732
Contents lists available at ScienceDirect
Nutrition journal homepage: www.nutritionjrnl.com
Letters to the editor
Lactulose in fat-free milk, rather than increased ghrelin and motilin level, might help for solving constipation: Author update To the Editor: In our study, “Fat-free milk as a therapeutic approach for constipation and the effect on serum motilin and ghrelin levels,” which was recently published in Nutrition, my colleagues and I reported that fat-free milk supplementation decreased or eliminated constipation through a mechanism that elevates serum motilin and ghrelin levels [1]. I also believe that another mechanism by which fat-free milk supplementation eliminates constipation originates from lactulose. Lactulose, which is an isomer of lactose (glucose and galactose), is obtained by a molecular rearrangement of lactose in an alkali and heat environment [2]. That is, glucose in lactose is replaced by fructose in lactulose (4-O-b-D-galactopyranosyl-D-fructose), an insoluble galacto-oligosaccharide that cannot be broken down by human digestive enzymes [3]. Previous studies have reported that different types of milk contain different amounts of the lactose isomer lactulose (range 10 to 90 mg/100 mL) [4], depending on the heating technique (e.g., ultrahigh temperature). Lactulose is one of the most commonly used gentle laxatives in constipation [5]. The laxative effect of lactulose arises two ways [5]: 1. primarily through the osmotic effect of lactulose sugar 2. secondarily through the osmotic effect resulting from the formation of acid metabolites by acting as a substrate for colonic bacteria Therefore, in addition to eliminating constipation through a mechanism that increases serum motilin and ghrelin levels, I argue that the other reason why fat-free milk was observed to eliminate constipation in our study could be a lactulose (a laxative) that is formed from lactose with the ultrahigh-temperature technique. References [1] Aydin S, Donder E, Akin OK, Sahpaz F, Kendir Y, Alnema MM. Fat-free milk as a therapeutic approach for constipation and the effect on serum motilin and ghrelin levels. Nutrition 2010;26:981–5. [2] Olano A, Corzo N. Lactulose as a food ingredient. J Sci Food Agric 2009;89: 1987–90. ndez-Ban ~ ares F, Esteve-Pardo M, de Leon R, Humbert P, Cabre E, [3] Ferna Llovet JM, Gassull MA. Sugar malabsorption in functional bowel disease: clinical implications. Am J Gastroenterol 1993;88:2044–50. [4] Cataldi TR, Angelotti M, Bufo SA. Method development for the quantitative determination of lactulose in heat-treated milks by HPAEC with pulsed amperometric detection. Anal Chem 1999;7:4919–25. 0899-9007/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved.
[5] Foxx-Orenstein AE, McNally MA, Odunsi ST. Update on constipation: one treatment does not fit all. Cleve Clin J Med 2008;75:813–24.
Suleyman Aydin, Ph.D. Department of Medical Biochemistry and Clinical Biochemistry (Firat Hormones Research Group) Firat University Hospital Elazig, Turkey doi:10.1016/j.nut.2010.11.002
Reply to Dr. Kang’s letter entitled “Effect of u-3 fatty acids on lifespan” To the Editor: My colleagues and I recently published our findings showing that mice given long-term fish oil develop severe oxidative stress and have a shortened lifespan [1]. Dr. Kang subsequently commented on this work [2] and we respond to those comments. Dr. Kang suggested that the harmful effect of fish oil intake is caused by the large amount of peroxides in the fish oil or the higher levels of antioxidants in the safflower oil. However, these points are inconsistent with our work [1], in which the diets were handled very carefully. The diets were stored in a bag filled with nitrogen at 35 C until feeding. Diets with peroxide levels lower than 10 mEq/kg (peroxide value) were routinely used. At this level, peroxide has no effect on the living body. Diets given to mice were changed every day. Moreover, to equate the vitamin E (tocopherol) concentration in the two oils, the total tocopherol content was determined using high-performance liquid chromatography with a fluorescence detector and was found to be 20.5 and 2.0 mg/100 g in the safflower oil and fish oil, respectively. Vitamin E (a-tocopherol) was added to produce a final concentration of 0.0205% in each oil. Thus, the level of antioxidants was similar in the two diets, which does not support Dr. Kang’s suggested mechanism. Dr. Kang also suggested that safflower oil and flaxseed oil are useful for comparing an u-6 fatty acid (linoleic acid) with an u-3 fatty acid (a-linolenic acid). The effects on longevity of linoleic acid and a-linolenic acid have been reported by other groups [3]. We found that the longevity of mice given a-linolenic acid was shorter than that of mice given linoleic acid. We want to emphasize that a long-term intake of u-3 fatty acids (fish oil) may possibly damage health. Previous studies have shown that almost all beneficial compounds also have negative effects (e.g., catechin and conjugated linoleic acid). It is not
Contents lists available at ScienceDirect
Nutrition journal homepage: www.nutritionjrnl.com
Letters to the editor
Lactulose in fat-free milk, rather than increased ghrelin and motilin level, might help for solving constipation: Author update To the Editor: In our study, “Fat-free milk as a therapeutic approach for constipation and the effect on serum motilin and ghrelin levels,” which was recently published in Nutrition, my colleagues and I reported that fat-free milk supplementation decreased or eliminated constipation through a mechanism that elevates serum motilin and ghrelin levels [1]. I also believe that another mechanism by which fat-free milk supplementation eliminates constipation originates from lactulose. Lactulose, which is an isomer of lactose (glucose and galactose), is obtained by a molecular rearrangement of lactose in an alkali and heat environment [2]. That is, glucose in lactose is replaced by fructose in lactulose (4-O-b-D-galactopyranosyl-D-fructose), an insoluble galacto-oligosaccharide that cannot be broken down by human digestive enzymes [3]. Previous studies have reported that different types of milk contain different amounts of the lactose isomer lactulose (range 10 to 90 mg/100 mL) [4], depending on the heating technique (e.g., ultrahigh temperature). Lactulose is one of the most commonly used gentle laxatives in constipation [5]. The laxative effect of lactulose arises two ways [5]: 1. primarily through the osmotic effect of lactulose sugar 2. secondarily through the osmotic effect resulting from the formation of acid metabolites by acting as a substrate for colonic bacteria Therefore, in addition to eliminating constipation through a mechanism that increases serum motilin and ghrelin levels, I argue that the other reason why fat-free milk was observed to eliminate constipation in our study could be a lactulose (a laxative) that is formed from lactose with the ultrahigh-temperature technique. References [1] Aydin S, Donder E, Akin OK, Sahpaz F, Kendir Y, Alnema MM. Fat-free milk as a therapeutic approach for constipation and the effect on serum motilin and ghrelin levels. Nutrition 2010;26:981–5. [2] Olano A, Corzo N. Lactulose as a food ingredient. J Sci Food Agric 2009;89: 1987–90. ndez-Ban ~ ares F, Esteve-Pardo M, de Leon R, Humbert P, Cabre E, [3] Ferna Llovet JM, Gassull MA. Sugar malabsorption in functional bowel disease: clinical implications. Am J Gastroenterol 1993;88:2044–50. [4] Cataldi TR, Angelotti M, Bufo SA. Method development for the quantitative determination of lactulose in heat-treated milks by HPAEC with pulsed amperometric detection. Anal Chem 1999;7:4919–25. 0899-9007/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved.
[5] Foxx-Orenstein AE, McNally MA, Odunsi ST. Update on constipation: one treatment does not fit all. Cleve Clin J Med 2008;75:813–24.
Suleyman Aydin, Ph.D. Department of Medical Biochemistry and Clinical Biochemistry (Firat Hormones Research Group) Firat University Hospital Elazig, Turkey doi:10.1016/j.nut.2010.11.002
Reply to Dr. Kang’s letter entitled “Effect of u-3 fatty acids on lifespan” To the Editor: My colleagues and I recently published our findings showing that mice given long-term fish oil develop severe oxidative stress and have a shortened lifespan [1]. Dr. Kang subsequently commented on this work [2] and we respond to those comments. Dr. Kang suggested that the harmful effect of fish oil intake is caused by the large amount of peroxides in the fish oil or the higher levels of antioxidants in the safflower oil. However, these points are inconsistent with our work [1], in which the diets were handled very carefully. The diets were stored in a bag filled with nitrogen at 35 C until feeding. Diets with peroxide levels lower than 10 mEq/kg (peroxide value) were routinely used. At this level, peroxide has no effect on the living body. Diets given to mice were changed every day. Moreover, to equate the vitamin E (tocopherol) concentration in the two oils, the total tocopherol content was determined using high-performance liquid chromatography with a fluorescence detector and was found to be 20.5 and 2.0 mg/100 g in the safflower oil and fish oil, respectively. Vitamin E (a-tocopherol) was added to produce a final concentration of 0.0205% in each oil. Thus, the level of antioxidants was similar in the two diets, which does not support Dr. Kang’s suggested mechanism. Dr. Kang also suggested that safflower oil and flaxseed oil are useful for comparing an u-6 fatty acid (linoleic acid) with an u-3 fatty acid (a-linolenic acid). The effects on longevity of linoleic acid and a-linolenic acid have been reported by other groups [3]. We found that the longevity of mice given a-linolenic acid was shorter than that of mice given linoleic acid. We want to emphasize that a long-term intake of u-3 fatty acids (fish oil) may possibly damage health. Previous studies have shown that almost all beneficial compounds also have negative effects (e.g., catechin and conjugated linoleic acid). It is not