North American Diet Research Articles

Abstract 4298: In-utero, but not pubertal, soy exposure suppresses estrogen-regulated gene expression in non-human primate breast

Abstract Background: Cynomolgus macaques (nonhuman primates, NHP) are highly similar to humans in their genetics, reproductive physiology, and anatomy. More importantly, they undergo a similar mammary gland development process and develop spontaneous breast cancers. Epidemiological studies of humans show that high soy intake is associated with lower breast cancer risk. Since nutrition and/or environmental exposure during youth are critical factors to disease risk in adulthood, timing of intervention may determine soy protective effect to breast cancer. Studies in NHP allow interrogation of developmental effects on the primate breast to a degree not possible in human subjects. We report here novel in-utero developmental effects of soy isoflavones (IF) on the NHP breast. Method: Soy IF were detected in amniotic fluid (255.5 + 93.3 nM) and milk (266.3 nM), which confirmed that soy exposure occurred in-utero and via nursing. We assessed the effects of in-utero and pre-pubertal soy exposure on the breast of NHP during puberty with a focus on changes related to estrogen exposure. We utilized mammary tissues from animals that were exposed to soy beginning in-utero (n=5 for soy and casein/control groups) or before puberty (n=12-17 for soy and casein groups). Animals were fed a diet modeled on a typical North American diet (35% calories from fat) with soy dose approximated at 120-180 mg IF/person/day. We assessed nipple length, mammary gland morphology, markers of mammary gland differentiation, proliferation, and estrogen receptor activity, and concentrations of serum estradiol and progesterone. Results: Regardless of dietary treatment, gene expression of estrogen-responsive markers in the breast was highest during pre-puberty and decreased across the pubertal transition (P<0.0001 for time effect on ESR1, PGR, GREB1, and TFF1). This pattern coincided with a decrease of terminal end bud structures and an increase of lobular differentiation and glandular area. Although an effect of dietary soy was not observed in pre-pubertally exposed animals, in-utero exposed animals showed lower expression of TFF1 (0.03-fold; P<0.05), a classic marker of estrogen receptor alpha (ER) activity. Serum estradiol level was not different with dietary treatment, nor did IF alter mRNA expression of estrogen-metabolizing enzymes in the breast. Conclusions and Future Directions: Our data suggest that timing of exposure may influence the effects of dietary soy on the breast; in-utero soy exposure resulted in modestly lower expression of a gene marker of ER activity, while pre-pubertal exposure had negligible effects on mammary gland outcomes. A follow-up study is currently underway to further examine potential effects of in-utero soy exposure on estrogen responsiveness and pubertal development, and whether epigenetic modulation is the underlying mechanism behind the differential expression of estrogen-related genes. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 4298. doi:1538-7445.AM2012-4298

Essential Nutrients for Bone Health and a Review of their Availability in the Average North American Diet.

Osteoporosis and low bone mineral density affect millions of Americans. The majority of adults in North America have insufficient intake of vitamin D and calcium along with inadequate exercise. Physicians are aware that vitamin D, calcium and exercise are essential for maintenance of bone health. Physicians are less likely to be aware that dietary insufficiencies of magnesium, silicon, Vitamin K, and boron are also widely prevalent, and each of these essential nutrients is an important contributor to bone health. In addition, specific nutritional factors may improve calcium metabolism and bone formation. It is the authors’ opinion that nutritional supplements should attempt to provide ample, but not excessive, amounts of factors that are frequently insufficient in the typical American diet.In contrast to dietary insufficiencies, several nutrients that support bone health are readily available in the average American diet. These include zinc, manganese, and copper which may have adverse effects at higher levels of intake. Some multivitamins and bone support products provide additional quantities of nutrients that may be unnecessary or potentially harmful.The purpose of this paper is to identify specific nutritional components of bone health, the effects on bone, the level of availability in the average American diet, and the implications of supplementation for each nutritional component. A summary of recommended dietary supplementation is included.

Viscosity rather than quantity of dietary fibre predicts cholesterol-lowering effect in healthy individuals

The well-documented lipid-lowering effects of fibre may be related to its viscosity, a phenomenon that has been understudied, especially when fibre is given against the background of a typical North American (NA) diet. In this three-arm experiment, we compared the lipid-lowering effect of low-viscosity wheat bran (WB), medium-viscosity psyllium (PSY) and a high-viscosity viscous fibre blend (VFB), as part of a fibre intervention aimed at increasing fibre intake to recommended levels within the context of a NA diet in apparently healthy individuals. Using a randomised cross-over design, twenty-three participants (twelve males and eleven females; age 35 (SD 12) years; LDL-cholesterol (C) 2.9 (SEM 0.6) mmol/l) consuming a typical NA diet received a standard, fibre-enriched cereal, where approximately one-third of the fibre was either a low-viscosity (570 centipoise (cP)) WB, medium-viscosity (14,300 cP) PSY or a high-viscosity (136,300 cP) novel VFB, for 3 weeks separated by washout periods of ≥ 2 weeks. There were no differences among the treatments in the amount of food consumed, total dietary fibre intake, reported physical activity and body weight. Final intake of the WB, PSY and VFB was 10.8, 9.0 and 5.1 g, respectively. Reduction in LDL-C was greater with the VFB compared with the medium-viscosity PSY (-12.6 (SEM 3.5) %, P = 0.002) and low-viscosity WB (-14.6 (SEM 4.2) %, P = 0.003). The magnitude of LDL-C reduction showed a positive association with fibre apparent viscosity (r - 0.41, P = 0.001). Despite the smaller quantity consumed, the high-viscosity fibre lowered LDL-C to a greater extent than lower-viscosity fibres. These data support the inclusion of high-viscosity fibre in the diet to reduce plasma lipids among apparently healthy individuals consuming a typical NA diet.

Quantifying ruminal nitrogen metabolism using the omasal sampling technique in cattle—A meta-analysis

Mixed model analysis of data from 32 studies (122 diets) was used to evaluate the precision and accuracy of the omasal sampling technique for quantifying ruminal-N metabolism and to assess the relationships between nonammonia-N flow at the omasal canal and milk protein yield. Data were derived from experiments in cattle fed North American diets (n=36) based on alfalfa silage, corn silage, and corn grain and Northern European diets (n=86) composed of grass silage and barley-based concentrates. In all studies, digesta flow was quantified using a triple-marker approach. Linear regressions were used to predict microbial-N flow to the omasum from intake of dry matter (DM), organic matter (OM), or total digestible nutrients. Efficiency of microbial-N synthesis increased with DM intake and there were trends for increased efficiency with elevated dietary concentrations of crude protein (CP) and rumen-degraded protein (RDP) but these effects were small. Regression of omasal rumen-undegraded protein (RUP) flow on CP intake indicated that an average 32% of dietary CP escaped and 68% was degraded in the rumen. The slope from regression of observed omasal flows of RUP on flows predicted by the National Research Council (2001) model indicated that NRC predicted greater RUP supply. Measured microbial-N flow was, on average, 26% greater than that predicted by the NRC model. Zero ruminal N-balance (omasal CP flow=CP intake) was obtained at dietary CP and RDP concentrations of 147 and 106g/kg of DM, corresponding to ruminal ammonia-N and milk urea N concentrations of 7.1 and 8.3mg/100mL, respectively. Milk protein yield was positively related to the efficiency of microbial-N synthesis and measured RUP concentration. Improved efficiency of microbial-N synthesis and reduced ruminal CP degradability were positively associated with efficiency of capture of dietary N as milk N. In conclusion, the results of this study indicate that the omasal sampling technique yields valuable estimates of RDP, RUP, and ruminal microbial protein supply in cattle.

Quantifying ruminal digestion of organic matter and neutral detergent fiber using the omasal sampling technique in cattle—A meta-analysis

A data set from 32 studies (122 diets) was used to evaluate the accuracy and precision of the omasal sampling technique by investigating the relationships between ruminal and total digestion of neutral detergent fiber (NDF), between intake and apparent and true ruminal digestion of organic matter (OM), and between omasal NAN flow and milk protein yield. A mixed model regression analysis with random study effect was used to evaluate the relationships. The data were obtained when feeding North American diets (n=36) based on alfalfa silage, corn silage, and corn grain and North European diets (n=86) comprising grass silage supplemented with barley-based concentrates. In all studies, digesta flow was quantified using a triple-marker approach. Standard deviations of ruminal NDF and true OM digestibility were smaller than typically reported in duodenal sampling studies using only chromic oxide as a flow marker. The relationship between total and ruminal NDF digestion was consistent, indicating little variation in the proportion of total-tract NDF digestion that occurred in the rumen. Furthermore, the slope of this regression indicated that 94.7% (±2.7%) of total NDF digestion occurred in the rumen. The slopes of mixed model regression equations between OM intake and amount digested indicated that 42% (±2.4%) and 74% (±3.1%) of OM was apparently and truly digested in the rumen, respectively. The contribution of the rumen to total-tract apparent OM digestion was 62% (±2.6%). The close relationship between omasal flow of nonammonia crude protein and milk protein yield (with adjusted residual mean squared error=31g) provided further confidence in the reliability of omasal flow measurements.

Choline: an essential nutrient for public health

Choline was officially recognized as an essential nutrient by the Institute of Medicine (IOM) in 1998. There is significant variation in the dietary requirement for choline that can be explained by common genetic polymorphisms. Because of its wide-ranging roles in human metabolism, from cell structure to neurotransmitter synthesis, choline-deficiency is now thought to have an impact on diseases such as liver disease, atherosclerosis, and, possibly, neurological disorders. Choline is found in a wide variety of foods. Eggs and meats are rich sources of choline in the North American diet, providing up to 430 milligrams per 100 grams. Mean choline intakes for older children, men, women, and pregnant women are far below the adequate intake level established by the IOM. Given the importance of choline in a wide range of critical functions in the human body, coupled with less-than-optimal intakes among the population, dietary guidance should be developed to encourage the intake of choline-rich foods.

A Method for Intercultivar Comparison of Potato Tuber Nutrient Content Using Specific Tissue Weight Proportions

Potato tubers are a staple food item in the North American diet. Each potato cultivar has unique tuber appearance and nutritional composition. A method was developed to facilitate better cultivar selection for dietary purposes and obtain a better understanding of the nutrient distribution within specific tissues of potato tubers. This involved a procedure for estimating the percent weight contribution of the 3 major tissue components, including periderm or "skin," cortex, and pith for 20 potato cultivars. Weight determination was based on the volume (calculated through an ellipsoid formula) and density of each component tissue. Calculated percent weight and dry matter data for each tuber tissue provided conversion factor values that were tabulated for all cultivars. An example is provided to illustrate the application of this procedure in facilitating identification of cultivars with significantly greater or lesser protein content.

Is increased dietary protein necessary or beneficial for individuals with a physically active lifestyle?

For most of the 20th century, scientists have believed that protein needs are not altered by physical exercise. In contrast, athletes are typically convinced that additional dietary protein can significantly enhance exercise performance. Until recently, the opinion of the athletes has been largely unsubstantiated in the scientific literature. However, since the 1970s, an increasing number of studies have appeared that indicate dietary protein needs are elevated in individuals who are regularly physically active. Together, these data suggest that the RDA for those who engage in regular endurance exercise should be about 1.2-1.4 g protein/kg body mass/d (150-175% of the current RDA) and 1.7-1.8 g protein/kg body mass/d (212-225% of the current RDA) for strength exercisers. Fortunately, the typical North American diet contains protein near these quantities, so most individuals who decide to begin an exercise program will obtain sufficient protein as long as their diet is mixed and they are careful to consume adequate energy. Populations at greatest risk for consuming insufficient protein include any group that restricts energy intake (those on diets) or high quality protein sources (vegetarians) as well as any group that has a requirement higher than normal due to another existing condition (growing individuals). Future studies should focus on these groups. Moreover, few exercise performance measures have been made, so any negative effect of insufficient dietary protein on athletic success needs to be determined. Supplementation of several individual amino acids may be beneficial for physically active individuals, but considerable potential risk is also present. Intake of large quantities of individual amino acids is not recommended until much more information is available.

External exposure and bioaccumulation of PCBs in humans living in a contaminated urban environment

Humans are exposed to different mixtures of PCBs depending on the route of exposure. In this study we investigated the potential contribution of inhalation to the overall human exposure to PCBs in an urban area. For this purpose, the mechanistically based, non-steady state bioaccumulation model ACC-HUMAN was applied to predict the PCB body burden in an adult living in the Midwestern United States who eats a typical North American diet and inhales air contaminated with PCBs. Dietary exposure was estimated using measured data for eighteen PCB congeners in different food groups (fish, meat and egg, dairy products). Two scenarios for inhalation exposure were evaluated: one using air concentrations measured in Chicago, and a second using air measurements in a remote area on Lake Michigan, Sleeping Bear Dunes. The model predicted that exposure via inhalation increases the accumulated mass of PCBs in the body by up to 30% for lower chlorinated congeners, while diet is by far the dominant source of exposure for those PCB congeners that accumulate most in humans.

Aging, IGF‐1, and diet

Fontana et al. (2008) recently reported in Aging Cell their interesting findings, based on studies of 46 subjects, of the impact of chronic severe caloric restriction on insulin-like growth factor 1 (IGF-1) and insulin-like growth factor binding protein 3 (IGFBP-3) levels. They concluded that protein intake may be a more important determinant of the circulating levels than energy restriction, and speculated that this may have implications with respect to longevity. We previously reported (Holmes et al. , 2002; Giovannucci et al. , 2003) studies of 1037 women and 753 men that explored dietary determinants of IGF-1 and IGFBP-3 levels in a crosssection of subjects on typical North American diets. We observed, in females, a positive association between protein intake with circulating IGF-1 concentration (174, 188, 201, 192, and 196 ng mL –1 across quintiles of protein intake; p = 0.002), which was stronger than the relationship between energy intake and IGF-1 concentration. Similar findings were seen in men, where the relationship of energy intake to IGF-1 levels was seen only in men with body mass index < 25 kg m –2 . Thus, the intervention study involving a small number of subjects by Fontana et al. yielded data consistent with the larger observational studies we previously reported. Caution is required in extrapolating data concerning dietaryinduced changes in IGF-1 levels to changes in health outcomes, such as longevity or cancer risk. While there is clear evidence that reduced IGF signalling is associated with increased longevity in model organisms, there is evidence that lower IGF-1 levels are associated with increased cardiovascular disease in humans (Brugts et al. , 2008). In addition, recent data (e.g. Ma et al. , 2008) suggest that with respect to cancer endpoints, it is important to consider insulin levels as well as IGF-1 levels. The relationships between diet, insulin and IGF-1 levels, and clinical health outcomes is an important topic, but one that appears to be more complex than might have been implied by animal models.

Cloning and expression of the major allergen genes in apple fruit

SummaryApple, the most common fruit in European and North American diets, can cause allergic reactions in susceptible individuals, and genes for four families of apple allergens have been identified to date: Mal d 1, Mal d 2, Mal d 3, and Mal d 4. Our remit was to evaluate the effects of genotype, tissue, and stage of fruit development on the expression of these allergen genes and, hence, on the potential allergenicity of apple fruit. Transcript levels were investigated in fruit of the apple cultivars, ‘Gala’ and ‘Florina’, using quantitative Real-Time PCR. The resulting patterns of allergen gene expression differed, with Mal d 1 and Mal d 2 being the most highly expressed in the skin and flesh of ripe fruit, respectively. Overall, ‘Florina’ fruit showed higher levels of expression than ‘Gala’ fruit for all allergens tested.

Are all n-3 polyunsaturated fatty acids created equal?

N-3 Polyunsaturated fatty acids have been shown to have potential beneficial effects for chronic diseases including cancer, insulin resistance and cardiovascular disease. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in particular have been studied extensively, whereas substantive evidence for a biological role for the precursor, alpha-linolenic acid (ALA), is lacking. It is not enough to assume that ALA exerts effects through conversion to EPA and DHA, as the process is highly inefficient in humans. Thus, clarification of ALA's involvement in health and disease is essential, as it is the principle n-3 polyunsaturated fatty acid consumed in the North American diet and intakes of EPA and DHA are typically very low. There is evidence suggesting that ALA, EPA and DHA have specific and potentially independent effects on chronic disease. Therefore, this review will assess our current understanding of the differential effects of ALA, EPA and DHA on cancer, insulin resistance, and cardiovascular disease. Potential mechanisms of action will also be reviewed. Overall, a better understanding of the individual role for ALA, EPA and DHA is needed in order to make appropriate dietary recommendations regarding n-3 polyunsaturated fatty acid consumption.

Impact of diet and stress on the development of preeclampsia-like symptoms in p57kip2 mice

The cyclin-dependent kinase inhibitor p57(kip2) regulates the cell cycle of trophoblastic cells. It has been established by a Japanese group that the heterozygous p57(kip2) knockout (p57(-/+)) mice are a good model of preeclampsia as they develop hypertension, proteinuria, and placental pathology. However, apart from the placental pathology, we could not observe these symptoms in our laboratory. Hence, we investigated the impact of diet and stress on this model. To do so, we compared the effects of the Japanese diet to that of the North American diet used by our animal facility. Furthermore, the impact of stress was determined by placing the mice in a restraining device before and at the end of gestation. Although the Japanese diet did not have any impact on blood pressure or proteinuria, the mice did develop endothelial dysfunction, left ventricular hypertrophy, as well as increased placental pathology. Also, all mice had smaller litters when fed the Japanese diet. However, stress response of these mice was not increased during gestation; in fact, a decrease was observed in the p57(-/+) mice, suggesting that this was probably not a player in the development of the pathology. Taken together, these results suggest that other environmental factors may have been implicated in the development of preeclampsia-like symptoms in this animal model. Moreover, we demonstrated that placental pathology and genetic factors are not sufficient to trigger preeclampsia-like symptoms in this model and that the diet might play an important part in the development of this multifactorial disease.

Direct Determinations of the Fatty Acid Composition of Daily Dietary Intakes Incorporating Nutraceuticals and Functional Food Strategies to Increase n-3 Highly Unsaturated Fatty Acids

Objective: North American diets are low in eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA). This investigation aims to assess the ability to increase EPA and DHA in the Canadian diet using traditional whole food, functional food or nutraceutical strategies.Methods: A typical Canadian diet (TC) was compared to four diets enriched with EPA and DHA but with similar caloric and macronutrient composition: a nutraceutical fish oil capsule diet (FO), an EPA + DHA-enriched functional foods diet (ED), a traditional whole foods (fish) diet (TW) and a comprehensive diet combining fish with functional foods (FF) containing EPA + DHA and α-linolenic acid. Direct biochemical quantitations were performed for energy, protein, carbohydrate (proximate analysis) and fat (gas chromatography). Costs of each diet and EPA + DHA source were assessed.Results: The FO (1.03 ± 0.01g EPA + DHA), ED (0.59 ± 0.02g), TW (3.23 ± 0.09g) and FF (3.15 ± 0.06g) diets provided significantly higher amounts of EPA + DHA compared to the TC diet (0.08 ± 0.01g). Using the TC diet as a baseline, the daily cost increase for each revised diet was $0.53 (FO), $0.82 (TW), $0.93 (ED) and $1.62 (FF). The cost per gram of EPA + DHA was lowest for fish oil nutraceuticals ($0.53/g), followed by fish (∼$1.05/g).Conclusions: The EPA and DHA content of daily diets can be increased significantly and cost effectively using nutraceuticals, functional foods and whole foods. Several North American EPA + DHA recommendations for healthy individuals can be met using these strategies and American Heart Association recommendations for secondary coronary heart disease prevention can be met via traditional whole food, nutraceutical or combination approaches.

The antihypertensive effect of arginine

Hypertension is a leading cause of morbidity and mortality worldwide. Individuals with hypertension are at increased risk of stroke, heart disease and kidney failure. Although the etiology of essential hypertension has a genetic component, lifestyle factors such as diet play an important role. Reducing dietary salt is effective in lowering blood pressure in salt-sensitive individuals. Insulin resistance and altered glucose metabolism are common features of hypertension in humans and animal models, with or without salt sensitivity. Altered glucose metabolism leads to increased formation of advanced glycation end products. Insulin resistance is also linked to oxidative stress, and alterations in the nitric oxide pathway and renin angiotensin system. A diet rich in protein containing the semiessential amino acid, arginine, and arginine treatment, lowers blood pressure in humans and in animal models. This may be due to the ability of arginine to improve insulin resistance, decrease advanced glycation end products formation, increase nitric oxide, and decrease levels of angiotensin II and oxidative stress, with improved endothelial cell function and decreased peripheral vascular resistance. The Dietary Approaches to Stop Hypertension (DASH) study demonstrated that the DASH diet, rich in vegetables, fruits and low-fat dairy products; low in fat; and including whole grains, poultry, fish and nuts, lowered blood pressures even more than a typical North American diet with similar reduced sodium content. The DASH diet is rich in protein; the blood pressure-lowering effect of the DASH diet may be due to its higher arginine-containing protein, higher antioxidants and low salt content.

Dietary phytoestrogen intake is associated with reduced colorectal cancer risk.

Evidence suggests dietary phytoestrogens may reduce the risk of certain hormonal cancers (e.g. breast and prostate). There is a paucity of data regarding phytoestrogens and colorectal cancer risk. Phytoestrogens are plant compounds with estrogen-like activities. Main classes include isoflavones (found in legumes such as soy) and lignans (found in grains, seeds, nuts, fruits, and vegetables). Although isoflavones have dominated phytoestrogen cancer research, lignans may be more relevant to North American diets. Food questionnaires and analytic databases have recently been modified to incorporate some lignan information. We conducted a case-control study to evaluate the association between phytoestrogen intake and colorectal cancer risk. Colorectal cancer cases were diagnosed in 1997-2000, aged 20-74 y, identified through the population-based Ontario Cancer Registry, and recruited by the Ontario Familial Colorectal Cancer Registry. Controls were a sex and age-group matched random sample of the population of Ontario. Epidemiologic and food frequency questionnaires were completed by 1095 cases and 1890 control subjects. Multivariate logistic regression analysis was used to obtain adjusted odds ratio (OR) estimates. Dietary lignan intake was associated with a significant reduction in colorectal cancer risk [OR (T3 vs. T1) = 0.73; 95% CI: 0.56, 0.94], as was isoflavone intake [OR (T3 vs. T1) = 0.71; 95% CI: 0.58, 0.86]. We evaluated interactions between polymorphic genes that encode enzymes possibly involved in metabolism of phytoestrogens (CYPs, catechol O-methyl transferase, GSTs, and UGTs) and found no significant effect modification with respect to phytoestrogen intake. This finding that phytoestrogen intake may reduce colorectal cancer risk is important, because dietary intake is potentially modifiable.

Endogenous Production and Elevated Levels of Long-Chain n-3 Fatty Acids in the Milk of Transgenic Mice

n-3 Polyunsaturated fatty acids (n-3 PUFA) are important for the normal development and functioning of all organisms. Mammals lack the n-3 fatty acid desaturase required for the synthesis of α-linolenic acid (18:3n-3), and are therefore dependent on dietary sources to obtain this essential fatty acid. Currently, the richest source of dietary long-chain n-3 PUFA, eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3), are triacylglycerides extracted from rapidly declining marine resources. The nematode Caenorhabditis elegans synthesizes a wide range of PUFA and possesses the only known example of an n-3 fatty acid desaturase enzyme in the animal kingdom. Transgenic mice expressing the C. elegans n-3 desaturase under the control of the lactation-induced goat β-casein mammary gland promoter were generated via pronuclear microinjection. Significant increases in n-3 PUFA, decreases in n-6 PUFA, and an overall decrease in the n-6:n-3 PUFA ratio were observed in the milk produced by transgenic mice. Neonate mice consuming milk from transgenic females accumulated increased levels of docosahexaenoic acid in their brains. This transgenic model may provide useful information to address some basic questions of neonatal nutrition, and demonstrates one of the steps that would be required to increase the n-3 PUFA content of milk and dairy products endogenously. Increasing the proportion of n-3 PUFA in milk fat would help to improve the nutritional composition of an important component of the North American diet.

Effects Of Different Fibers On Bowel Habits In Healthy Individuals

Objective To investigate safety and efficacy of insoluble (wheat, corn) and soluble (Psyllium, and viscous fiber blend- PGX) fiber on bowel habits in healthy individuals. Methods Using a randomized, single blind, crossover design, participants were placed on a typical North American metabolic diet (50% carbohydrates, 35% fat and 15% protein, dietary fiber 15±5 g/day) and received addition of either: All Bran (AB), Bran Buds with Corn (BBC), Bran Buds with Psyllium (BBP), viscous fiber blend (PGX) breakfast cereals, or a low-fiber wheat based cereal (control) for three weeks separated by at least one-week washout period. Twenty three healthy participants (12M:11F, age 35±12 years, BMI 24±5 kg/m2) were included in the final analyses. Changes in bowel habits and symptom diary were compared to baseline and the low fiber control. Results All study cereals - AB, BBC, BBP and PGX - induced significant increases in wet stool weight compared to control (52%, 55%, 85% and 49% respectively, p<0.05) and baseline (50%, 52%, 83% and 47%, p<0.05), with lower stool weight in females in all groups. AB, BBC, BBP and PGX also significantly increased stool frequency compared to control (21%, 24%, 31% and 28%,p<0.05) and baseline (15%, 18%, 25% and 22%, respectively, p<0.05), with no significant side effects. Conclusions Addition of breakfast cereals containing different sources of water-insoluble and soluble dietary fibers to a metabolically controlled, typical North American diet, increases both stool weight and frequency of bowel movement. The Psyllium enriched breakfast cereal was more effective than other studied fibers in promoting fecal bulk. Research Support: Kellogg’s Company, Inovobiologic Inc, Calgary

Viscosity rather than quantity determines lipid lowering effects of dietary fiber in individuals consuming typical North American diet

Objective To investigate the role of low (wheat), medium (psyllium), and high (viscous fiber blend PGXTM) viscosity fibers on serum lipid profile. Methods Using a randomized, single blind, crossover design, 22 healthy participants (12M:10F, 34±11 years) on a typical North American diet (50% carbohydrates, 35% fat and 15% protein) and dietary fiber intake 15±5 g/day received addition of either Wheat Bran (WB), Bran Buds with Psyllium (BBP), or PGX (4.7 g/day) cereals, or low-fiber wheat flour cereal (control) for three weeks separated by one-week washout periods. Results Comparison between PGX and the control showed that the addition of PGX to the diet significantly lowered serum levels of cholesterol (6.5%, p=0.008), triglycerides (24.0%, p=0.02), ApoB (3.8%, p=0.048), LDL (7.1%, p=0.047), cholesterol/HDL (9.3%, p=0.004), and LDL/HDL (8.4%, p=0.045). Compared to the baseline, PGX significantly decreased serum levels of cholesterol (10.4%, p<0.0001), ApoB (5.7%, p=0.0005), LDL (13.3%, p=0.0007), cholesterol/HDL (9.6%, p=0.001), and LDL/HDL (11.1%, p=0.002) at the end of the 3-week study period. Other diets (WB, BBP) did not induce significant changes in lipid levels except elevation in ApoB and cholesterol at week 3 on the AB diet. Comparison between diets showed superior lipid-lowering effect of PGX. Conclusion The addition of a high viscous fiber PGX, but not wheat bran or psyllium, to a metabolically controlled typical North American diet significantly improves blood lipid profile in healthy subjects. Viscosity rather than quantity determines lipid lowering effects of dietary fiber. Research Support: Inovobiologic Inc, Calgary

Effects of Antinutritional Factors on Protein Digestibility and Amino Acid Availability in Foods

Digestibility of protein in traditional diets from developing countries such as India, Guatemala, and Brazil is considerably lower compared to that of protein in typical North American diets (54-78 versus 88-94%). The presence of less digestible protein fractions, high levels of insoluble fiber, and high concentrations of antinutritional factors in the diets of developing countries, which are based on less refined cereals and grain legumes as major sources of protein, are responsible for poor digestibility of protein. The effects of the presence of some of the important antinutritional factors on protein and amino digestibilities of food and feed products are reviewed in this chapter. Food and feed products may contain a number of antinutritional factors that may adversely affect protein digestibility and amino acid availability. Antinutritional factors may occur naturally, such as glucosinolates in mustard and rapeseed protein products, trypsin inhibitors and hemagglutinins in legumes, tannins in legumes and cereals, phytates in cereals and oilseeds, and gossypol in cottonseed protein products. Antinutritional factors may also be formed during heat/alkaline processing of protein products, yielding Maillard compounds, oxidized forms of sulfur amino acids, D-amino acids, and lysinoalanine (LAL, an unnatural amino acid derivative). The presence of high levels of dietary trypsin inhibitors from soybeans, kidney beans, or other grain legumes can cause substantial reductions in protein and amino acid digestibilities (up to 50%) in rats and pigs. Similarly, the presence of high levels of tannins in cereals, such as sorghum, and grain legumes, such as fababean (Vicia faba L.), can result in significantly reduced protein and amino acid digestibilities (up to 23%) in rats, poultry, and pigs. Studies involving phytase supplementation of production rations for swine or poultry have provided indirect evidence that normally encountered levels of phytates in cereals and legumes can reduce protein and amino acid digestibilities by up to 10%. D-amino acids and LAL formed during alkaline/heat treatment of proteins such as casein, lactalbumin, soy protein isolate, or wheat proteins are poorly digestible (less than 40%), and their presence can reduce protein digestibility by up to 28% in rats and pigs. A comparison of the protein digestibility determination in young (5-week) versus old (20-month) rats suggests greater susceptibility to the adverse effects of antinutritional factors in old rats than in young rats. Therefore, the inclusion of protein digestibility data obtained with young rats, as the recommended animal model, in the calculation of PDCAAS (Protein Digestibility-Corrected Amino Acid Score) may overestimate protein digestibility and quality of products, especially those containing antinutritional factors, for the elderly. For products specifically intended for the elderly, protein digestibility should be determined using more mature rats.