Fiber and Things...

[Emma-Leigh]

Just a few articles...

J Nutr. 1997 Oct;127(10):2000-5. Links
The western lowland gorilla diet has implications for the health of humans and other hominoids.

Popovich DG, Jenkins DJ, Kendall CW, Dierenfeld ES, Carroll RW, Tariq N, Vidgen E.
Clinical Nutrition and Risk Factor Modification Center, St. Michael's Hospital, Toronto, Canada.
We studied the western lowland gorilla diet as a possible model for human nutrient requirements with implications for colonic function. Gorillas in the Central African Republic were identified as consuming over 200 species and varieties of plants and 100 species and varieties of fruit. Thirty-one of the most commonly consumed foods were collected and dried locally before shipping for macronutrient and fiber analysis. The mean macronutrient concentrations were (mean +/- SD, g/100 g dry basis) fat 0.5 +/- 0.4, protein 11.8 +/- 8.2, available carbohydrate 7.7 +/- 6.3 and dietary fiber 74.0 +/- 12.9. Assuming that the macronutrient profile of these foods was reflective of the whole gorilla diet and that dietary fiber contributed 6.28 kJ/g (1.5 kcal/g), then the gorilla diet would provide 810 kJ (194 kcal) metabolizable energy per 100 g dry weight. The macronutrient profile of this diet would be as follows: 2.5% energy as fat, 24.3% protein, 15.8% available carbohydrate, with potentially 57.3% of metabolizable energy from short-chain fatty acids (SCFA) derived from colonic fermentation of fiber. Gorillas would therefore obtain considerable energy through fiber fermentation. We suggest that humans also evolved consuming similar high foliage, high fiber diets, which were low in fat and dietary cholesterol. The macronutrient and fiber profile of the gorilla diet is one in which the colon is likely to play a major role in overall nutrition. Both the nutrient and fiber components of such a diet and the functional capacity of the hominoid colon may have important dietary implications for contemporary human health.
PMID: 9311957 [PubMed - indexed for MEDLINE]

Adv Exp Med Biol. 1997;427:35-42.Links
What is a high fiber diet?

Wolever TM, Jenkins DJ.
Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Ontario, Canada.
There is no recognized definition of what constitutes a high fiber diet. Intakes of dietary fiber in different populations internationally vary widely from less than 20 g to more than 80 g per day. The types of foods contributing fiber also vary; in some countries cereals contribute the most fiber, in others leafy or root vegetables predominate. Vegetables have the highest fiber content per Kcal, and in most populations with fiber intakes over 50 g, vegetables contribute over 50% of total fiber intake. In rural Uganda, where the fiber hypothesis was first developed by Burkitt and Trowell, vegetables contribute over 90% of fiber intake. An experimental diet, the "Simian" diet, has been developed to mimic as closely as possible using human foods, the diet consumed by our simian ancestors the great apes. It is also similar to the Ugandan diet in containing large amounts of vegetables and 50 g fiber/1000 Kcal. Though nutritionally adequate, this diet is very bulky and not a suitable model for general recommendations. Dietary guidelines are that fat intake should be < 30% of energy, with a fiber intake of 20-35 g/d. These recommendations are inconsistent with a high fiber diet because, for people consuming more than about 2400 Kcal, low fiber choices for fruits and grains must be selected to keep dietary fiber intake within the range of 20-35 g. In a 30% fat, 1800 Kcal omnivorous diet, selection of wholemeal bread and whole fruit, results in a fiber intake over 35 g/d, and for and 1800 Kcal vegetarian diet, with substitution of modest amounts of peanut butter and beans for meats, dietary fiber intake goes up to 45 g/d. Thus, if it is desirable to promote the use of unrefined foods, the recommended dietary fiber intake should be a minimum of 15-20 g/1000 Kcal.
PMID: 9361828 [PubMed - indexed for MEDLINE]

Am J Clin Nutr. 1995 Nov;62(5 Suppl):1158S-1160S. Links
Contribution of fiber and resistant starch to metabolizable energy.

Behall KM, Howe JC.
Diet and Human Performance Laboratory, Beltsville Human Nutrition Research Center, US Department of Agriculture, MD 20705, USA.
Recommendations made to increase complex carbohydrate and fiber intake in the United States may result in energy loss from increased fecal losses of starch, protein, and fat. The type of fiber or starch and the amount consumed affect digestion of the carbohydrate and interactions with other nutrients. On average, 8.4 kJ (2 kcal) digestible energy/g is available from up to 70 g poorly digested carbohydrate/d. Undigested fiber and starch are important substrates for colon bacteria and are fermented to short-chain fatty acids, hydrogen, and methane. Hydrogen and methane excreted through the lungs have been used as indicators of colonic fermentation. Fermentation appears to contribute significant digestible energy when > 20 g poorly digested carbohydrate/d is consumed.
PMID: 7484936 [PubMed - indexed for MEDLINE]

Eur J Clin Nutr. 2007 Dec;61 Suppl 1:S40-74. Links
Physiological aspects of energy metabolism and gastrointestinal effects of carbohydrates.

Elia M, Cummings JH.
Institute of Human Nutrition, University of Southampton, Southampton, UK. elia@soton.ac.uk
The energy values of carbohydrates continue to be debated. This is because of the use of different energy systems, for example, combustible, digestible, metabolizable, and so on. Furthermore, ingested macronutrients may not be fully available to tissues, and the tissues themselves may not be able fully to oxidize substrates made available to them. Therefore, for certain carbohydrates, the discrepancies between combustible energy (cEI), digestible energy (DE), metabolizable energy (ME) and net metabolizable energy (NME) may be considerable. Three food energy systems are in use in food tables and for food labelling in different world regions based on selective interpretation of the digestive physiology and metabolism of food carbohydrates. This is clearly unsatisfactory and confusing to the consumer. While it has been suggested that an enormous amount of work would have to be undertaken to change the current ME system into an NME system, the additional changes may not be as great as anticipated. In experimental work, carbohydrate is high in the macronutrient hierarchy of satiation. However, studies of eating behaviour indicate that it does not unconditionally depend on the oxidation of one nutrient, and argue against the operation of a simple carbohydrate oxidation or storage model of feeding behaviour to the exclusion of other macronutrients. The site, rate and extent of carbohydrate digestion in, and absorption from the gut are key to understanding the many roles of carbohydrate, although the concept of digestibility has different meanings. Within the nutrition community, the characteristic patterns of digestion that occur in the small (upper) vs large (lower) bowel are known to impact in contrasting ways on metabolism, while in the discussion of the energy value of foods, digestibility is defined as the proportion of combustible energy that is absorbed over the entire length of the gastrointestinal tract. Carbohydrates that reach the large bowel are fermented to short-chain fatty acids. The exact amounts and types of carbohydrate that reach the caecum are unknown, but are probably between 20 and 40 g/day in countries with 'westernized' diets, whereas they may reach 50 g/day where traditional staples are largely cereal or diets are high in fruit and vegetables. Non-starch polysaccharides clearly affect bowel habit and so, to a lesser extent, does resistant starch. However, the short-chain carbohydrates, which are also found in breast milk, have little if any laxative role, although do effect the balance of the flora. This latter property has led to the term 'prebiotic', which is defined as the capacity to increase selectively the numbers of bifidobacteria and lactobacilli without growth of other genera. This now well-established physiological property has not so far led through to clear health benefits, but current studies are focused on their potential to prevent diarrhoeal illnesses, improve well-being and immunomodulation, particularly in atopic children and on increased calcium absorption.
PMID: 17992186 [PubMed - indexed for MEDLINE]

[Emma-Leigh]

More....

Br J Nutr. 2005 Jul;94(1):1-11. Links
Carbohydrate bioavailability.

Englyst KN, Englyst HN.
Englyst Carbohydrates, 2 Venture Road, Chilworth Science Park, Southampton, UK. Klaus@Englyst.co.uk
There is consensus that carbohydrate foods, in the form of fruit, vegetables and whole-grain products, are beneficial to health. However, there are strong indications that highly processed, fibre-depleted, and consequently rapidly digestible, energy-dense carbohydrate food products can lead to over-consumption and obesity-related diseases. Greater attention needs to be given to carbohydrate bioavailability, which is determined by the chemical identity and physical form of food. The objective of the present concept article is to provide a rational basis for the nutritional characterisation of dietary carbohydrates. Based on the properties of carbohydrate foods identified to be of specific relevance to health, we propose a classification and measurement scheme that divides dietary carbohydrates into glycaemic carbohydrates (digested and absorbed in the small intestine) and non-glycaemic carbohydrates (enter the large intestine). The glycaemic carbohydrates are characterised by sugar type, and by the likely rate of digestion described by in vitro measurements for rapidly available glucose and slowly available glucose. The main type of non-glycaemic carbohydrates is the plant cell-wall NSP, which is a marker of the natural fibre-rich diet recognised as beneficial to health. Other non-glycaemic carbohydrates include resistant starch and the resistant short-chain carbohydrates (non-digestible oligosaccharides), which should be measured and researched in their own right. The proposed classification and measurement scheme is complementary to the dietary fibre and glycaemic index concepts in the promotion of healthy diets with low energy density required for combating obesity-related diseases.
PMID: 16115326 [PubMed - indexed for MEDLINE]

Crit Rev Food Sci Nutr. 2009 Apr;49(4):327-60. Links
Gastrointestinal effects of low-digestible carbohydrates.

Grabitske HA, Slavin JL.
Department of Food Science and Nutrition, University of Minnesota, 1334 Eckles Avenue, St. Paul, MN 55108, USA.
Low-digestible carbohydrates (LDCs) are carbohydrates that are incompletely or not absorbed in the small intestine but are at least partly fermented by bacteria in the large intestine. Fiber, resistant starch, and sugar alcohols are types of LDCs. Given potential health benefits (including a reduced caloric content, reduced or no effect on blood glucose levels, non-cariogenic effect) the prevalence of LDCs in processed foods is increasing. Many of the benefits of LDCs are related to the inability of human digestive enzymes to break down completely the carbohydrates into absorbable saccharides and the subsequent fermentation of unabsorbed carbohydrates in the colon. As a result, LDCs may affect laxation and cause gastrointestinal effects, including abdominal discomfort, flatus, and diarrhea, especially at higher or excessive intakes. Such responses, though transient, affect the perception of the well-being of consumers and their acceptance of food products containing LDCs. Current recommendations for fiber intake do not consider total LDC consumption nor recommend an upper limit for LDC intake based on potential gastrointestinal effects. Therefore, a review of published studies reporting gastrointestinal effects of LDCs was conducted. We included only studies published in refereed journals in English. Additionally, we excluded studies of subjects with incomplete or abnormal functioning gastrointestinal tracts or where antibiotics, stimulant laxatives, or other drugs affecting motility were included. Only in studies with a control period, either placebo treatment or no LDC treatment, were included. Studies must have included an acceptable measure of gastrointestinal effect. Sixty-eight studies and six review articles were evaluated. This review describes definitions, classifications, and mechanisms of LDCs, evaluates published human feeding studies of fifteen LDCs for associations between gastrointestinal effects and levels of LDC intake, and presents recommendations for LDC consumption and further research.
PMID: 19234944 [PubMed - indexed for MEDLINE]

[Tom Bro]

A few interesting ones in there.
I don't know if I necessarily agree with the mass adding of fibre to foods like milk. Especially if the fibre source is something like inulin.

[Holyspokes]

Interesting, thanks Emma. I was also reading one of the studies that you posted in another thread where it was saying that Increased fiber intake can cause the body to digest/absorb less protein and fat from the diet... but I couldn't quite figure out how significant it was?

[Tom Bro]

I'd imagine it depends largely on how close to consuming your fibre you're consuming your other nutrients. If the bulk is further down your digestive tract, it's less likely to interfere with other nutrient absorption. It would also depend on the ratio of fibre:nutrients.

[EmperorRyker]

Interesting, thanks Emma. I was also reading one of the studies that you posted in another thread where it was saying that Increased fiber intake can cause the body to digest/absorb less protein and fat from the diet... but I couldn't quite figure out how significant it was?

Yeah, I actually heard a similar thing, as well, and saw being advised against taking omega-3 supplements with fibrous food, since the latter is supposed to bind the fats and therefore your body doesn't really absorb them.

[Emma-Leigh]

Try these:
http://jn.nutrition.org/cgi/content/full/127/4/579

The Journal of Nutrition Vol. 127 No. 4 April 1997, pp. 579-586
Copyright ?1997 by the American Society for Nutritional Sciences

Dietary Fiber Decreases the Metabolizable Energy Content and Nutrient Digestibility of Mixed Diets Fed to Humans1

David J. Baer2, William V. Rumpler, Carolyn W. Miles, and George C. Fahey Jr.*

U.S. Department of Agriculture, Agricultural Research Service, Diet and Human Performance Laboratory, Beltsville Human Nutrition Research Center, Beltsville, MD 20705 and * Department of Animal Sciences, University of Illinois, Urbana, IL 61801

ABSTRACT
INTRODUCTION
SUBJECTS AND METHODS
RESULTS
DISCUSSION
FOOTNOTES
LITERATURE CITED

ABSTRACT

Food labeling regulations implemented by the U.S. Food and Drug Administration emphasize nutrient composition and energy content of foods. Dietary energy and digestibility of complex foods can be affected by the content and type of dietary fiber. The metabolizable energy (ME) content and apparent digestibility of dietary fiber in human diets are difficult to assess. Fiber can affect the digestibility of fat and protein and, subsequently, the ME content of the diet. This study was conducted to measure the ME content of nine diets with different fat and fiber concentrations. Diets varied in level of fat (18, 34 or 47% of energy) and level of total dietary fiber (3, 4 or 7% of diet dry matter) and were consumed for 2 wk. Subjects (n = 17) consumed three diets (14 d for each diet) containing different levels of fiber and one level of fat. Food consumption was measured and all urine and feces were collected during a 5-d period. Combustible energy, protein, fat, total dietary fiber (TDF) and neutral detergent fiber (NDF) were measured in composite samples of food and feces, and urine was analyzed for combustible energy and nitrogen. Metabolizable energy and apparent digestibility coefficients were calculated. Overall, increasing fiber intake decreased fat and protein digestibility. As a consequence of these interactions, the ME content of the diets decreased as fiber intake increased, and TDF and NDF had similar effects on the ME value. A published empirical formula accurately predicted the ME content of diets using either TDF or NDF

[Emma-Leigh]

More:

J Nutr. 1988 Sep;118(9):1075-81.Related Articles, Links

Effect of dietary fiber on the metabolizable energy of human diets.

Miles CW, Kelsay JL, Wong NP.

U.S. Department of Agriculture, Beltsville Human Nutrition Research Center, MD 20705.

Two diets consisting of natural foods that differed in fiber content were fed to 12 men for 6 wk each in a crossover design. Diet 1 contained 37 g total dietary fiber (TDF) from fruits and vegetables and diet 2 contained 16 g TDF from fruit and vegetable juices in a 2800-kcal menu. Seven-day food, urine and fecal composites were made and analyzed for their gross energy, fat, protein and carbohydrate content during the fourth and fifth weeks of each dietary consumption period. The metabolizable energy (ME) of these diets was determined (gross energy of the diet - gross energy of urine and feces) and calculated by Atwater's general energy conversion factors (4, 9, 4), by specific energy conversion factors used in a U.S. food table and by formulas derived by various researchers. The coefficients of availability of energy and the energy-containing nutrients, fat, protein and carbohydrate, were lower while subjects were consuming the higher fiber diet. The specific energy conversion factors of the U.S. food table gave better estimates of the true ME of the lower fiber diet than the higher fiber diet, overestimating the ME of these diets by only 6% (diet 1) and 4.6% (diet 2).

PMID: 2843615 [PubMed - indexed for MEDLINE]

J Nutr. 1980 Oct;110(10):2020-6. Links
Effect of refined cellulose on apparent energy, fat and nitrogen digestibilities.

Slavin JL, Marlett JA.
Seven young women consumed a low cellulose diet for about 1 month and then the same diet for an additional month except that 16 g/day Solka Floc was added to the diet. Apparent digestibilities of energy, fat and nitrogen were measured for each subject during each diet. Digestibilities of fat and nitrogen were not affected by refined cellulose ingestion. Digestibility of nitrogen was 93.2% without and 92.9% with the Solka Floc, while fat digestibility was 96.3% during the control diet and 95.4% during the high cellulose diet. Mean digestibility of gross energy decreased significantly when cellulose was added to the diet, from 95.4% to 92.0% (P < 0.01). Undigested fecal fiber was the major source of the increased fecal energy. When fecal fiber energy was subtracted from total fecal energy and apparent energy digestibility recalculated, there was no difference in apparent energy digestibility during the 2 diets, 96.1% without and 95.6% with the Solka Floc supplement. Thus, ingestion of 16 g/day Solka Floc had no detrimental effect on the utilization of nitrogen and fat and increases in fecal energy could be explained by undigested refined cellulose.
PMID: 6252303 [PubMed - indexed for MEDLINE]

[Confuzzl3dOn3]

Just a quick question Emma, about how much fibre should we be getting daily? I usually probably eat heaps of vegies however its usually lettuce in the morning at brekkie, and lettuce again in sandwiches for lunch. My mum keeps complaining about having to buy too much lettuce because it isn't that cheap so i was thinking of cutting back and not needing to eat that much lettuce and looking for some cheaper vegies that are possibly more nutritious and good amount of fibre. Basically how much fibre and how much vegies should 1 intake daily?

[determined4000]

Just a quick question Emma, about how much fibre should we be getting daily? I usually probably eat heaps of vegies however its usually lettuce in the morning at brekkie, and lettuce again in sandwiches for lunch. My mum keeps complaining about having to buy too much lettuce because it isn't that cheap so i was thinking of cutting back and not needing to eat that much lettuce and looking for some cheaper vegies that are possibly more nutritious and good amount of fibre. Basically how much fibre and how much vegies should 1 intake daily?

35-50g
But lettuce really isn't very high in fiber compared to other veggies (spinach, broccoli, cauliflower)
Buy some frozen spinach. I can get a pound for $1. (about 13g of fiber vs. 4-5g for lettuce)
Also there are many wraps or pitas that have really high amounts of fiber
They are generally considered/labeled "lowcarb" because they have so much fiber the net carb count is low.
I know I m not the expert u wanted but no one had replied.

[Confuzzl3dOn3]

35-50g
But lettuce really isn't very high in fiber compared to other veggies (spinach, broccoli, cauliflower)
Buy some frozen spinach. I can get a pound for $1. (about 13g of fiber vs. 4-5g for lettuce)
Also there are many wraps or pitas that have really high amounts of fiber
They are generally considered/labeled "lowcarb" because they have so much fiber the net carb count is low.
I know I m not the expert u wanted but no one had replied.

Only forzen spinach i've seen is about equalt to $5 for 1kg. So it's more like 2 bucks a pound here. Hopefully i can find a cheaper place.

[caa5000]

dude... there are plenty of high fiber carbohydrates out there doesn't have to be veggies.

1 serving of mini-wheats = 5g
1 high fiber wrap = 5g
1 servings fiber one pancakes = 5g

[Confuzzl3dOn3]

Not sure whether there are these in Aussie. I'm sure there are just haven't looked out for em. I'll look around next time i'm at the supermarket.

[Emma-Leigh]

How much fiber you need depends on a few things, but the minimum I suggest is ~ 20g per 1000 kCal of energy intake (around 40-50g a day is good).

Vegetables are the same - but I normally am of the opinion of 'more is good'...

For fiber -> there are much better sources than lettuce.

[Confuzzl3dOn3]

Thx Emma. I think im normally getting heaps and heaps of fibre. So it'll probs be ok if i cut back on it a bit. It's gonna be difficult now to get enough fibre though because i just got my wisdom teeth pulled out yesterday and it hurts like hell.

[determined4000]

Only forzen spinach i've seen is about equalt to $5 for 1kg. So it's more like 2 bucks a pound here. Hopefully i can find a cheaper place.

look at it this way
you get 120calories/b frozen spinach and 60-65/lb of lettuce

[determined4000]

dude... there are plenty of high fiber carbohydrates out there doesn't have to be veggies.

1 serving of mini-wheats = 5g
1 high fiber wrap = 5g
1 servings fiber one pancakes = 5g

The wrap I use are 10-12g of fiber
1 serving carbquik pancakes =14g fiber
1 serving kashi golean cereal= 10g fiber

[Holyspokes]

How much fiber you need depends on a few things, but the minimum I suggest is ~ 20g per 1000 kCal of energy intake (around 40-50g a day is good).

Vegetables are the same - but I normally am of the opinion of 'more is good'...

For fiber -> there are much better sources than lettuce.

Does this still apply to people taking in ~5,000 kcals of food? Meaning, 100g of fiber/day ?!

I'm more interested in the effects fiber has on Nutrients/Hormones (test) than ME. I tried searching around, but I seem to suck at Lit searches.

[signature166]

So, uhhh, can you affect the ME by taking "probiotic" supps? What about affecting the nutrients/hormone absorption by taking "probiotic" supps?

[AbAbber2k]

Wow, interesting stuff.

So we get about 2kcal per gram of fiber through fermentation and the metabolism of SCFAs? Gorillas must eat non-stop if that's where >50% of their caloric intake comes from. :P

So beyond colonic health would there be any other benefits to a VERY high fiber diet? It looks like a high fiber diet would be beneficial for those on a cut. Not only is fiber very filling but it apparently stunts absorption of pro/cho. Is there anything else I'm missing? Possibly related to SCFAs?

[in10city]

A few other things to consider especially if fiber is displacing other food items.

One thing that is fairly certain is that increasing fiber intake - more related to the lignin and insoluble fiber content - increases fecal testosterone, estrone, and estradiol excretion. Urinary testosterone excretion is lower and estrone and estradiol excretion is higher in high fiber/low fat diets compared to low fiber/high fat diets as well.

However, only some data has supported the that increased fecal excretion is correlated to lower plasma levels. It does appear that age plays a role - the older one is the more likely that the inverse relation holds. Some of the data also suggests that higher fiber intake may increase SHBG concentration and may alter the bound : unbound testosterone ratio but protein & fat intake is likely a confounder in the data since it showed slightly lower testosterone for the high fiber/low fat diet compared to the low fiber/high fat diet too.

Not to mention that there are other confounding factors like exercise, body composition, and other dietary factors that would need to be applied towards the net effect.

[Holyspokes]

A few other things to consider especially if fiber is displacing other food items.

Thanks in10city.. where's that from?

[in10city]

Thanks in10city.. where's that from?

That was a response that I wrote to a PM asking about the relationship between fiber intake and testosterone. These are some of the more applicable studies.

1. Dietary and hormonal evaluation of men at different risks for prostate cancer: plasma and fecal hormone-nutrient interrelationships.

2. Dietary and hormonal evaluation of men at different risks for prostate cancer: fiber intake, excretion, and composition, with in vitro evidence for an association between steroid hormones and specific fiber components.

3. Effects of dietary fat and fiber on plasma and urine androgens and estrogens in men: a controlled feeding study.

4. Dietary and hormonal interrelationships among vegetarian Seventh-Day Adventists and nonvegetarian men.

[determined4000]

That was a response that I wrote to a PM asking about the relationship between fiber intake and testosterone. These are some of the more applicable studies.

1. Dietary and hormonal evaluation of men at different risks for prostate cancer: plasma and fecal hormone-nutrient interrelationships.

2. Dietary and hormonal evaluation of men at different risks for prostate cancer: fiber intake, excretion, and composition, with in vitro evidence for an association between steroid hormones and specific fiber components.

3. Effects of dietary fat and fiber on plasma and urine androgens and estrogens in men: a controlled feeding study.

4. Dietary and hormonal interrelationships among vegetarian Seventh-Day Adventists and nonvegetarian men.

so you would seem to advocate high fat over low fat diets
Main benefits in layman's terms if you dont mind my ignorance?
What do you define as high fiber and high fat? Based on g/lb or calories?
Does the source of fiber (ex. veggies vs. whole grains) or fat (saturated vs unsaturated) matter?

[fgfan1]

it seems like a lot of the things i eat, and coincidentally a lot of the things that i like to eat have a fair amount of fiber in them. at the end of the day it does really seem to add up- is this something i should be concerned with? or should i just try to lower my fiber to the best of my ability and brush it off?

[Emma-Leigh]

showed up in my email today:

Am J Clin Nutr (August 19, 2009). doi:10.3945/ajcn.2009.27990

Effect of daily fiber intake on reproductive function: the BioCycle Study1,2,3

Audrey J Gaskins, Sunni L Mumford, Cuilin Zhang, Jean Wactawski-Wende, Kathleen M Hovey, Brian W Whitcomb, Penelope P Howards, Neil J Perkins, Edwina Yeung, Enrique F Schisterman and for the BioCycle Study Group
1 From the Division of Epidemiology, Statistics, and Prevention Research, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD (AJG, SLM, CZ, NJP, EY, and EFS); the Department of Social and Preventive Medicine, University at Buffalo, State University of New York, Buffalo, NY (JW-W and KMH); the Division of Biostatistics and Epidemiology, University of Massachusetts, Amherst, MA (BWW); and the Department of Epidemiology, Emory University, Atlanta, GA (PPH).

2 Supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health.

3 Address correspondence and reprint requests to EF Schisterman, Epidemiology Branch, Eunice Kennedy Shriver National Institute of Child Health and Human Development, 6100 Executive Boulevard, 7B03M, Rockville, MD 20852. E-mail: schistee@mail.nih.gov.


ABSTRACT

Background: High-fiber diets have been associated with decreased breast cancer risk, likely mediated by the effect of fiber on lowering circulating estrogen concentrations. The influence of fiber on aspects of reproduction, which include ovulation, has not been well studied in premenopausal women.

Objective: The objective was to determine if fiber consumption is associated with hormone concentrations and incident anovulation in healthy, regularly menstruating women.

Design: The BioCycle Study was a prospective cohort study conducted from 2004 to 2006 that followed 250 women aged 18?44 y for 2 cycles. Dietary fiber consumption was assessed 4 times/cycle by using 24-h recall. Outcomes included concentrations of estradiol, progesterone, luteinizing hormone (LH), and follicle-stimulating hormone (FSH), which were measured 8 times/cycle, and incident anovulation.

Results: Dietary fiber consumption was inversely associated with hormone concentrations (estradiol, progesterone, LH, and FSH; P < 0.05) and positively associated with the risk of anovulation (P = 0.003) by using random-effects models with adjustment for total calories, age, race, and vitamin E intake. Each 5-g/d increase in total fiber intake was associated with a 1.78-fold increased risk (95% CI: 1.11, 2.84) of an anovulatory cycle. The adjusted odds ratio (aOR) of 5 g fruit fiber/d was 3.05 (95% CI: 1.07, 8.71).

Conclusions: These findings suggest that a diet high in fiber is significantly associated with decreased hormone concentrations and a higher probability of anovulation. Further study of the effect of fiber on reproductive health and of the effect of these intakes in reproductive-aged women is warranted.

Received for publication April 27, 2009. Accepted for publication July 12, 2009.

^^

all you blokes with high fiber intakes + really low test levels -->> might want to think about this as another factor....

[Confuzzl3dOn3]

showed up in my email today:

^^

all you blokes with high fiber intakes + really low test levels -->> might want to think about this as another factor....

Wait, i thought it said that fibre reduces estrogen...does it lower test and hormones generally as well? I would have thought high fiber diets would be a good way for us blokes to lower estrogen and increase testosterone according to what the article said.

[Emma-Leigh]

Wait, i thought it said that fibre reduces estrogen...does it lower test and hormones generally as well? I would have thought high fiber diets would be a good way for us blokes to lower estrogen and increase testosterone according to what the article said.

No.
Taking the male equivalent - it would lower test... Reason being is that if it lowers FSH/ LH then you'll end up decreasing test in a male.

[Confuzzl3dOn3]

No.
Taking the male equivalent - it would lower test... Reason being is that if it lowers FSH/ LH then you'll end up decreasing test in a male.

Ahh, so too much fibre is bad. Eeekk, i always thought fibre was good and the more the merrier. I never really monitored my fibre intake but i eat lots of fruits and vegies and oats...

[Valjean]

I wanna hear more on this. We can't just presume that, but it's certainly something to look into.