Interesting new facts on digestion. [Forum Archive]

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Interesting new facts on digestion.

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Posted by: Trouble

Well now, some research groups have been busy little bees testing new hypotheses on digestion rates - variations among cultures, living at differnt lattitudes, and seasonal rate variations (a function of ambient thermal regimes and light intensity at night. Even post-parandial body position influences digestion rates and adsorptivity.

Thought I would share them here..

Seasonal variation in amount of unabsorbed dietary carbohydrate from the intestine after breakfast in Japanese subjects. Tsumura Y, Hirota N, Tokura H, Rutkowska D, Sone Y. Chronobiol Int. 2005;22(6):1107-19.

We previously showed that daytime dim-light exposure has a negative effect on the efficiency of dietary carbohydrate absorption in the evening, whereas evening-time dim-light exposure has a beneficial effect. These results suggest that seasonal changes in the environmental light may affect gastrointestinal activity, and that there might, therefore, be seasonal variation in the efficiency of dietary carbohydrate absorption from the intestine.

In order to prove this hypothesis, we measured the amount of dietary carbohydrate unabsorbed from the intestine after a breakfast in healthy female Japanese subjects during the four seasons of the year. We estimated the amount of unabsorbed dietary carbohydrate by the breath hydrogen test, which measures the amount of hydrogen in exhaled air.

A 6 g solution of lactosucrose, an indigestible trisaccharide, was used for comparison. Two groups of subjects, 12 subjects in Osaka and 14 subjects in Nagano, were studied in the winter (January to February), spring (April to May), summer (July to August), and autumn (October to November) of 2004.

We found the following results: (1) In no season were there any significant differences between the two subgroups in the orocecal transit time of the breakfast and the lactosucrose solution. Nor were there any significant differences in the amount of unabsorbed dietary carbohydrate from the breakfast. (2) Using the pooled data of the total of 26 subjects, there was no significant seasonal variation in the orocecal transit time of the breakfast or the lactosucrose solution. (3) There was a significant seasonal variation in the amount of unabsorbed dietary carbohydrate from the breakfast. (4) The amount of unabsorbed dietary carbohydrate from the breakfast was largest in winter and smallest in autumn. Results in spring and in summer were similar and intermediate between those in winter and autumn. Post hoc multiple comparison tests showed that the amount of unabsorbed dietary carbohydrate in winter was significantly larger than in autumn. (5) In winter, the average ratio of the amount of unabsorbed dietary carbohydrate to the total amount of carbohydrate in the breakfast was about 12%; in autumn it was about 6%. These results clearly show that there is seasonal variation in the efficiency of intestinal dietary carbohydrate absorption among young female Japanese subjects.

Ready to get your mind blown?

Effects of dim or bright-light exposure during the daytime on human gastrointestinal activity. Sone Y, Hyun KJ, Nishimura S, Lee Yee and Tokura H. Chronobiol Int. 2003 Jan;20(1):123-33.

On the basis of our previous findings that bright-light exposure during the daytime has profound influence on physiological parameters such as melatonin secretion and tympanic temperature in humans, we proposed the hypothesis that bright vs. dim light-exposure during the daytime has a different influence on the activity of the digestive system via the endocrine and/or autonomic nervous system.

To examine this hypothesis, we conducted a series of counterbalanced experiments in which subjects stayed the daytime (7:00 to 15:00h) under either a dim (80 lux) or bright (5,000 lux) light condition. We measured gastrointestinal activity using a breath hydrogen (indicative of carbohydrate malabsorption) and an electrogastrography (EGG, indicative of gastric myoelectric activity) test.

The results showed the postprandial breath hydrogen excretion during the following nighttime period after daytime exposure to the dim-light condition was significantly higher than under the bright-light condition (p < 0.05). In addition, the spectrum total power of the EGG recorded after taking the evening meal was significantly lower for the dim than bright-light condition (p < 0.05). These results support our hypothesis and indicate that dim-light exposure during the daytime suppresses the digestion of the evening meal, resulting in malabsorption of dietary carbohydrates in it.

I verifed this independently myself, this summer. Working conditions, 2 months, in dimly lit daytime conditions (darkened office). No change in diet, in exertion rates. Two months spent in similar conditions, but with twice daily periods in bright sunlight, 20-30 minutes, between 9am and 5pm. Duration: May-August 2006. Results: weight gained in the first two months (6.4 +/- 0.5 lbs) was lost, without excess exertion. This would seem to indicate that the Japanese study has merit.

These results, indicative of cortisol and melatonin circadian programming from bright light exposure, were verified in other studies, which also indicated that briight light exposure beneficially promotes immune regulation.

Bright light exposure during the daytime affects circadian rhythms of urinary melatonin and salivary immunoglobulin A. Park SJ and H. Tokura. Chronobiol Int. 1999 May;16(3):359-71.

The effects of bright light exposure during the daytime on circadian urinary melatonin and salivary immunoglobulin A (IgA) rhythms were investigated in an environmental chamber controlled at a global temperature of 27 degrees C+/-0.2 degrees C and a relative humidity of 60%+/-5%. Seven diurnally active healthy females were studied twice, in bright and dim light conditions. Bright light of 5000 lux was provided by placing fluorescent lamps about 1 meter in front of the subjects during the daytime exposure (06:30-19:30) from 06:30 on day 1 to 10:30 on day 3. Dim light was controlled at 200 lux, and the subjects were allowed to sleep from 22:30 to 06:30 under both light exposure conditions. Urine and saliva were collected at 4h intervals for assessing melatonin and IgA.

Melatonin excretion in the urine was significantly greater during the nighttime (i.e., at 06:30 on day 1 and at 02:30 on day 2) after the bright light condition than during the dim light condition. Furthermore, the concentration and the amount of salivary IgA tended to be higher in the bright light than in the dim light condition, especially during the night-time. Also, salivary IgA concentration and the total amount secreted in the saliva were significantly positively correlated with urinary melatonin. These results are consistent with the hypothesis that bright light exposure during the daytime enhances the nocturnal melatonin increase and activates the mucosal immune response.

For those of you who read posts in my section, you will know that this intestinal mucosal activation correlates with improved muscle, skin, and connective tissue building and repair, muscle matrix support, and immune system regulation (read: reduced allergies and asthma).

Posted by: Trouble

Ethnic/cultural variation in digestion rates (probably a function of ethnic food variations and eating habits, as well as cultural differences in activity and food preferences (Japanese foods are especially rich in probiotics).

Comparison of carbohydrate digestion between Japanese and Polish healthy subjects. Tsumura Y, Hirota N, Tokura H, Sone Y, Lesinski F, Rutkowska D,
and Barinow-Wojewodzki A. Graduate School of Human Life Science, Osaka City University. J Physiol Anthropol Appl Human Sci. 2005 Jul;24(4):507-9.

We have revealed that light environment affects digestion and absorption of dietary carbohydrates in the gastrointestinal tract. This experimental result supposes that the efficiency of carbohydrate absorption may differ among people who live in different latitudes, such as Japanese and Polish people, at the same calendar season. In order to prove this hypothesis, we have been comparing the efficiency of carbohydrate absorption using the breath hydrogen test in Japan and Poland.

Here, we report the comparison of the result obtained in the summer of 2004 as the following; (1) Orocecal transit time (OCTT) for indigestible trisaccharide of Japanese subjects was significantly longer than that in Poland (p = 0.043). (2) On the ingestion of minestrone, the amount of unabsorbed carbohydrate of Japanese subjects (which was estimated as trisaccharide equivalent) was significantly larger than that of Polish subjects (p = 0.006).

Not surprisingly, sitting on your kester after eating a carb meal affects both transit time and digestion efficiency.

Effect of postprandial posture on digestion and absorption of dietary carbohydrate. Hirota N, Sone Y and Tokura H. J Physiol Anthropol Appl Human Sci. 2002 21(1):45-50

The effect of postprandial body posture on digestion and absorption of dietary carbohydrate were examined through breath hydrogen test on 6 female subjects. During the experiment, the participants either sat on a chair or lay on their backs for the first 4 hr (from 08:00 to 12:00) after eating the test breakfast meal. They then remained sedentary on a sofa for 6 hr (12:00 to 18:00). Participants' end alveolar breath samples were collected for 10 hr (every 15 min from 08:00 to 12:30, and then every 30 min until 18:00). The experiment was conducted on two consecutive days using a randomized, crossover study design.

The results demonstrated that in the supine position orocecal transit time of the test meal was significantly slower than in the sitting position (260 +/- 21 min and 238 +/- 20 min, respectively, p < 0.01). In addition, afternoon breath hydrogen excretion due to a partial malabsorption of dietary carbohydrate and its fermentation in the colon was significantly larger in the sitting position (144.0 +/- 24.1 ppm.hr) than in the supine position (110.0 +/- 26.1 ppm.hr, p < 0.05). These results support the hypothesis that there was a marked effect of postprandial body posture on the function of the digestive system. The present findings suggest that the postprandial supine position is preferable to the sitting position for the digestion and absorption of dietary carbohydrate.

Supine = Lying on the back or having the face upward.

http://www.jstage.jst.go.jp/article/jpa/23/3/75/_pdf

The authors attribute this difference in position on digestion of proteins to the effects body position on sympathetic nerve function (parastalsis, slow gastric emptying) and parasympathetic activity on digestion efficacy.

Posted by: P-funk

Why are all these studies on Japanese people?

I can't believe they did a study as recent as 2002 on digestion during a supine or seated posture.....I thought that was common knowledge?

Posted by: P-funk

also, I wonder what the physical state of the tested individuals was? I mean, would the digestion rate be effected in the first few studies if the subjects had weight trained....then how much would digestion be effected by light? Would it really matter?

Posted by: P-funk

note to self:

*when eating ice cream, be sure to do it under a large light bulb*

Posted by: Bakerboy

Quote:

Originally Posted by P-funk

note to self:

*when eating ice cream, be sure to do it under a large light bulb*

Posted by: P-funk

I hope the ice cream doesn't melt.....that would suck ass.

Posted by: Trouble

Quote:

Originally Posted by P-funk

also, I wonder what the physical state of the tested individuals was? I mean, would the digestion rate be effected in the first few studies if the subjects had weight trained....then how much would digestion be effected by light? Would it really matter?

Light effects vitamin D metabolism. Vitamin D3 metabolism in brain and liver significantly affects melatonin and 5-HT receptors, and thus immune function and anabolism. It profoundly affects circadian rhythm, and thus, growth hormone and IGF-1 induction.

I have used thermal stimulus (dry sauna) and light box stimulus to prevent weight gain over the winter and to induce weight loss in early spring. This was on a limited basis, I tested it on myself first.

Light levels affect autocrine function, via the light receptors in the eye. High stress loads increase the sensitivity to light and the amount of brain excitation with shifting light levels - such as in rapid changes in monitors (computers and TV). This has been demonstrated by lateration in GABAnergic and Glutamanergic receptors activity in brain sensory input processing loci - these connect to the HPA. Note that autocrine funciton influence digestion rates and absorption efficiency. Too fast = not very good absorption. Too fast (also) = too much fast degrading carbs hitting fermentation bacteria ==> acetate dominance --> glutamate production in liver --> metabolic issues, including insulin insensitivity and excessive intestinal sensitivity to sympathetic (beta adrenergic) stimulus --> feedback effect to improper digestion and fast peristalisis..and so on. Viscious cycle.

Last time I looked, digestion and absorption rates had a lot to do with both anabolism and immune function --> muscle building.

Why Japanese people? Japanese gov't funded these studies, thats why. I don't see the NIH pumping money into similar studies, and I don't see the FDA altering their views on low fat, higher carb lower protein diets, do you?

*zipping mouth shut*

Posted by: Trouble

Determination of glycaemic index; some methodological aspects related to the analysis of carbohydrate load and characteristics of the previous evening meal. Granfeldt Y, Wu X, and I. Bjorck I Department of Applied Nutrition and Food Chemistry, Department of Food Technology, Engineering and Nutrition, Lund University, Sweden. Eur J Clin Nutr. 2006 Jan 60(1):104-12.

OBJECTIVES: To determine the possible differences in glycaemic index (GI) depending on (1) the analytical method used to calculate the 'available carbohydrate' load, that is, using carbohydrates by difference (total carbohydrate by difference, minus dietary fibre (DF)) as available carbohydrates vs available starch basis (total starch minus resistant starch (RS)) of a food rich in intrinsic RS and (2) the effect of GI characteristics and/or the content of indigestible carbohydrates (RS and DF) of the evening meal prior to GI testing the following morning.

DESIGN: Blood glucose and serum insulin responses were studied after subjects consuming (1) two levels of barley kernels rich in intrinsic RS (15.2%, total starch basis) and (2) after a standard breakfast following three different evening meals varying in GI and/or indigestible carbohydrates: pasta, barley kernels and white wheat bread, respectively.

SUBJECTS: Healthy adults with normal body mass index.

RESULTS: (1) Increasing the portion size of barley kernels from 79.6 g (50 g 'available carbohydrates') to 93.9 g (50 g available starch) to adjust for its RS content did not significantly affect the GI or insulin index (11). (2) The low GI barley evening meal, as opposed to white wheat bread and pasta evening meals, reduced the postprandial glycaemic and insulinaemic (23 and 29%, respectively, P < 0.05) areas under the curve at a standardized white bread breakfast fed the following morning.

CONCLUSION: (1) Increasing portion size to compensate for the considerable portion of RS in a low GI barley product had no significant impact on GI or II. However, for GI testing, it is recommended to base carbohydrate load on specific analyses of the available carbohydrate content. (2) A low GI barley evening meal containing high levels of indigestible carbohydrates (RS and DF) substantially reduced the GI and II of white wheat bread determined at a subsequent breakfast meal.

Thus, the use of generous portions of slow digesting cereal brans that contain slow digesting soluble and insoluble fibers in shakes the day before will influence insulin production and release, and blood glucose response to higher carb loading the following morning.

Conjecture: This may be of help in reducing exaggerated glucose response in individuals who have disturbed sleep cycles (delayed sleep phase syndrome) or who miss meals the previous afternoon or evening due to circumstances beyond their control. I have noted this (in deliberate testing on self) but have not seen it confirmed in the research literature.

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