Showing papers in "Journal of The American College of Nutrition in 1993"

The role of trace minerals in osteoporosis.

Abstract: Osteoporosis is a multifactorial disease with dimensions of genetics, endocrine function, exercise and nutritional considerations. Of particular considerations are calcium (Ca) status, Vitamin D, fluoride, magnesium and other trace elements. Several trace elements, particularly copper (Cu), manganese (Mn) and zinc (Zn), are essential in bone metabolism as cofactors for specific enzymes. Our investigations regarding the role of Cu, Mn and Zn in bone metabolism include data from studies with animals on Cu- and Mn-deficient diets. We have also demonstrated cellular deficiencies using bone powder implants, as well as fundamental changes in organic matrix constituents. In clinical studies we have demonstrated the efficacy of Ca, Cu, Mn and Zn supplementation on spinal bone mineral density in postmenopausal women. Each of these studies demonstrated the necessity of trace elements for optimal bone matrix development and bone density sustenance.

Reducing atherogenic risk in hyperlipemic humans with flax seed supplementation: a preliminary report.

Abstract: The effect on serum lipids of a flax seed supplement consisting of three slices of flax seed-containing bread and 15 g of ground flax seed was studied in 15 hyperlipemic subjects on long-term intake (800 IU/day) of vitamin E. The flax seed, which was high in alpha-linolenic acid and fiber, and which has been reported to lower serum cholesterol in elderly subjects, was provided in a 3-month feeding trial. Serum total and low-density lipoprotein cholesterol levels were reduced significantly; high-density lipoprotein cholesterol did not change during flax seed consumption. Thrombin-stimulated platelet aggregation decreased with the supplement. Serum lipid oxidation products decreased significantly during the washout period.

Physical activity, physical fitness, and all-cause mortality in women: do women need to be active?

Abstract: Physical inactivity is associated with higher mortality rates in most studies in men, but studies in women are more equivocal. The purpose of this study was to evaluate the relationship of sedentary living habits to all-cause mortality in women. A group of 3,120 adult women completed a preventive medical examination, and were followed for approximately 8 years for mortality. There were 43 deaths and a total of 25,433 person-years observed during follow-up. Physical fitness was assessed at baseline by a maximal exercise test on a treadmill, and physical activity was estimated by a self-administered questionnaire. Age-adjusted all-cause mortality rates were significantly inversely associated with physical fitness. Death rates were 40, 16, and 7 per 10,000 person-years of follow-up across low, moderate, and high categories of physical fitness, respectively. However, death rates did not differ across low, moderate, and high categories of physical activity. These findings are different than for men in the same...

Cataract: relationship between nutrition and oxidation.

Abstract: Opacification of the lens, or cataract, is causally related to the precipitation of proteins or other constituents upon aging. Proteins in the lens are unusually long lived and are subject to extensive damage, including (photo)oxidation. Accumulation of damaged proteins also appears to be due in part to attenuated activity of some proteolytic pathways, which in younger tissue may serve to identify and remove such moieties. The damaged proteins accumulate, aggregate, and precipitate. Compared with other health problems, surgery to remove cataract and related visits to physicians consume the largest proportion of the Medicare budget, i.e., $3.2 billion annually in the United States. The situation is exacerbated in many parts of the world where there is a dearth of ophthalmologists to perform the required number of procedures. Historically efforts to delay cataract assumed a low profile in ophthalmologic research. Recent data, however, indicate that consuming elevated levels of antioxidants such as ascorbate, carotenoids, and tocopherol is associated with delayed development of various forms of cataract. The same beneficial relationship to vision pertains to plasma antioxidant status and to fruit and vegetable intake. Thus, it seems that assuring optimal antioxidant intake can extend lens function. It has been estimated that in the United States over half of the cataract extractions and associated costs would be obviated if cataract could be delayed by 10 years. The data reviewed indicate that optimizing nutrition will help achieve that objective.

Dietary magnesium affects susceptibility of lipoproteins and tissues to peroxidation in rats.

Abstract: Magnesium (Mg)-deficient and control diets were pair-fed to weanling Wistar rats for 8 days. Plasma lipoproteins were separated into various density classes by sequential preparative ultracentrifugation. The extent of lipid peroxidation was measured in terms of thiobarbituric acid reactive substances in lipoproteins and tissue homogenates before or after iron-induced lipid peroxidation. Hyperlipemia in Mg-deficient rats was accompanied by increased oxidation of very-low-density lipoproteins and low-density lipoproteins. Moreover, very-low-density lipoproteins and high-density lipoproteins from Mg-deficient rats were more susceptible to oxidative damage following iron incubation. Mg deficiency increased lipid peroxidation in liver, heart and skeletal muscles. Their homogenates were more susceptible to in vitro peroxidation. Mg deficiency has been discussed as a possible contributory factor in the development of cardiovascular disease and was associated with tissue damage and membrane alteration. These resu...

Body image and eating behavior in adolescents.

Abstract: Approximately two-thirds of adolescent girls at any age are dissatisfied with their weight, the proportion increasing with actual weight Slightly more than half of all girls are dissatisfied with the shape of their bodies, an attitude which also is positively correlated with body weight Girls are most likely to be distressed about excess size of their thighs, hips, waist and buttocks, and inadequate size of their breasts Those who are dissatisfied with their bodies are more likely to engage in potentially harmful weight control behaviors, such as dieting, fasting, self-induced vomiting, diuretic use, laxative use and diet pill use Those who diet are more likely to begin in early adolescence, to be white than black, to be of higher socioeconomic status, to engage in other eating-related practices and to have a poor body image and self esteem Boys who are underweight are most likely to be dissatisfied with their weight and many with normal weight wish to weigh more Approximately one-third of boys are dissatisfied with their body shape, desiring larger upper arms, chest and shoulders Dieting and purging are less likely than exercise to be chosen by boys as methods of weight control Dieting among boys is more likely to be associated with increased body weight and some sports, such as wrestling Body consciousness and altered body image are widespread among adolescents, and may be associated with potentially harmful eating practices in both sexes, but more so in girls

Antioxidants and cardiovascular disease: a review.

Abstract: In spite of the significant decline in cardiovascular disease (CVD) mortality over the past several decades, CVD remains the leading cause of death in the United States. Although age-specific CVD rates are higher in men than women, CVD is nonetheless the leading cause of death for both sexes, and is responsible for approximately one-third of all fatalities in women as well as men. Antioxidant vitamins are a promising area of current research in the prevention of CVD. The postulated mechanism for such an effect derives from basic research demonstrating the ability of antioxidants to inhibit the oxidation of low-density lipoprotein cholesterol. Epidemiologic studies that have explored the antioxidant vitamin hypothesis include descriptive and cross-sectional studies, analytic investigations using case-control and prospective cohort study designs, as well as several small randomized clinical trials. Findings from these studies are not totally consistent, but generally support the hypothesis that antioxidant vitamins reduce the risk of CVD. Overall, there are fewer data in women than men. Large-scale randomized trials are now ongoing that will provide reliable evidence on this question. The ongoing Physicians' Health Study of over 22,000 men is testing beta-carotene, while the recently begun Women's Health Study of 40,000 women will test, utilizing a factorial design, beta-carotene as well as vitamin E. A trial has also recently been funded to test beta-carotene, vitamin E and vitamin C in secondary prevention among a high-risk population of 8,000 women with prior CVD events.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastrointestinal and nutritional aspects of eating disorders

Abstract: Anorexia nervosa (AN) and bulimia nervosa (BN) are potentially fatal eating disorders which primarily affect adolescent females. Differentiating eating disorders from primary gastrointestinal (GI) disease may be difficult. GI disorders are common in eating disorder patients, symptomatic complaints being seen in over half. Moreover, many GI diseases sometimes resemble eating disorders. Inflammatory bowel disease, acid peptic diseases, and intestinal motility disorders such as achalasia may mimic eating disorders. However, it is usually possible to distinguish these by applying the diagnostic criteria for eating disorders and by obtaining common biochemical tests. The primary features of AN are profound weight loss due to self starvation and body image distortion; BN is characterized by binge eating and self purging of ingested food by vomiting or laxative abuse. GI complications in eating disorders are common. Recurrent emesis in BN is associated with dental abnormalities, parotid enlargement, and electrolyte disturbances including metabolic alkalosis. Hyperamylasemia of salivary origin is regularly seen, but may lead do an erroneous diagnosis of pancreatitis. Despite the weight loss often seen in eating disorders, serum albumin, cholesterol, and carotene are usually normal. However, serum levels of trace metals such as zinc and copper often are depressed, and hypophosphatemia can occur during refeeding. Patients with eating disorders frequently have gastric emptying abnormalities, causing bloating, postprandial fullness, and vomiting. This usually improves with refeeding, but sometimes treatment with pro-motility agents such as metoclopromide is necessary. Knowledge of the GI manifestations of eating disorders, and a high index of suspicion for one condition masquerading as the other, are required for the correct diagnosis and management of these patients.

A review of the epidemiology of nutrition and adolescent pregnancy: maternal growth during pregnancy and its effect on the fetus.

Abstract: Maternal growth during adolescent pregnancy and its effects on pregnancy outcome have been a source of controversy Maternal growth during pregnancy has been difficult to quantify because of the tendency of young and older women to “shrink” in stature with pregnancy In the Camden Study, maternal growth during pregnancy was monitored with the Knee Height Measuring Device, which measures growth of the lower leg, a body segment less susceptible to “shrinkage” Attempts of other investigators to detect maternal growth during adolescent pregnancy are reviewed here New data from the Camden Study, also presented, suggest that growing adolescents have infants that weigh less compared to nongrowing adolescents and mature controls (aged 19-29 years) Prior work had suggested that the effects of maternal growth on birth weight were confined to adolescent multiparas However, with expanded enrollment it was found that infants of growing primiparas and multiparas were both affected The hypothesis of the competition

Dietary supplementation with vitamins C and E inhibits in vitro oxidation of lipoproteins.

Abstract: The oxidative modification of lipoproteins has been implicated in atherogenesis, suggesting a protective role of circulating antioxidants. Vitamin C (ascorbic acid, 1 g/day) and vitamin E (dl alpha-tocopheryl acetate, 800 IU/day) were administered to healthy female and male volunteers. Lipoproteins with density < 1.063 g/mL were isolated from serum before and after vitamin supplementation and incubated with copper (Cu) or mononuclear cells (MC) plus Cu. Administration of vitamins C and E together to 4 subjects for 10 days resulted in a 57% (range 40-72%) decrease in Cu-catalyzed production of thiobarbituric acid reactive substances (TBARS) under the following conditions of assay: incubation times of 0-8 hours, Cu concentrations of 0-10 microM lipoprotein protein concentrations of 0.1–0.5 mg/mL. Decreases in other parameters of lipoprotein oxidation, i.e,, electrophoretic mobility, production of conjugated dienes and modification of amino groups, were also observed. Vitamin E administration alone produced ...

Antioxidant micronutrients and breast cancer.

Abstract: We reviewed epidemiologic evidence on the relationship between four antioxidant micronutrients (vitamin A, vitamin C, vitamin E, and selenium) and breast cancer risk. Available data support a modest protective effect of vitamin A, although more studies are needed to examine further this association and to assess the relative contributions of preformed vitamin A (retinol) and carotenoids. In addition, the possibility that some other component of vitamin A-rich foods may account for this observed association should be explored. Data on the relationship between vitamins C and E and breast cancer risk are limited and inconsistent, and further information is necessary. A substantial body of evidence indicates a lack of any appreciable effect of selenium intake on breast cancer risk, at least within the range of human diets. Future observational studies should ideally be prospective in design, as prospective studies are less prone to selection and recall bias than are case-control studies, and should address methodologic issues such as confounding by other micronutrients and appropriate storage conditions of blood specimens. Although hypotheses relating micronutrient intake to risk of breast cancer should be tested in randomized trials, ethical and logistical constraints make these studies difficult to perform.

The effect of fat and carbohydrate on plasma glucose, insulin, C-peptide, and triglycerides in normal male subjects.

Abstract: Ten normal subjects were given 50 g starch, or 50 g starch + 50 g fat as a breakfast meal The starch was given in the form of potato; the fat was given in the form of butter The meals were ingested at 8 am Plasma glucose, insulin, C-peptide, and triglyceride concentrations were measured at various time points for 4 hours after each meal The net 4-hour postprandial area responses to the ingested meals were determined using the trapezoid rule, with the fasting glucose concentration, measured at the same time points for 4 hours as a baseline The glucose area response was 22 mmol hour/l following the potato meal This was significantly reduced following ingestion of the meal containing fat (13 mmol hour/l) (p < 001) The insulin area response was slightly greater following the meal containing fat (459 pmol hour/l) compared to potato alone (423 pmol hour/l) (p < 001) The C-peptide area response following the meal containing fat was 080 pmol hour/ml, clearly greater than following potato alone (058 pmol hour/ml) (p < 001) The triglyceride area response also was much greater following the meal containing fat compared to potato alone (074 and 008 mmol hour/l, respectively) The mechanism of the attenuated glucose response to carbohydrate ingestion with a fat-containing meal is unknown It may be due to the release of an enteric hormone that increases glucose disposal, either directly or indirectly, through insulin

Niacin deficiency and cancer in women.

Abstract: A new interest in the relationship between niacin and cancer has evolved from the discovery that the principal form of this vitamin, NAD, is consumed as a substrate in ADP-ribose transfer reactions. Poly(ADP-ribose) polymerase, an enzyme activated by DNA strand breaks, is the ADP-ribosyltransferase of greatest interest with regard to effects on the niacin status of cells since its Km for NAD is high, and its activity can deplete NAD. Studies of the consequences of DNA damage in cultured mouse and human cells as a function of niacin status have supported the hypothesis that niacin may be a protective factor that limits carcinogenic events. To test this hypothesis in humans, we used a biochemical method based on the observation that as niacin nutriture decreases, NAD readily declines and NADP remains relatively constant. This has been demonstrated in both fibroblasts and in whole blood from humans. Thus, we use "niacin number," (NAD/NAD+NADP) x 100% from whole blood, as a measure of niacin status. Healthy control subjects showed a mean niacin number of 62.8 +/- 3.0 compared to 64.0 for individuals on a niacin-controlled diet. Analyses of women in the Malmo Diet and Cancer Study showed a mean niacin number of 60.4 with a range of 44 to 75. The distribution of niacin status in this population was nongaussian, with an unpredictably large number of individuals having low values.

Interrelationship of magnesium and estrogen in cardiovascular and bone disorders, eclampsia, migraine and premenstrual syndrome.

Abstract: The anticonvulsive and antihypertensive values of magnesium (Mg) in eclampsia, and its antiarrhythmic applications in a variety of cardiac diseases, have caused Mg to be considered only for parenteral administration by many physicians. In contrast, nutritionists have long recognized Mg as an essential nutrient, because severe deficiencies elicit neuromuscular manifestations similar to those justifying its use in eclampsia. More recently, this element has been used to favorably influence latent tetany with and without thrombotic complications, to delay preterm birth, to influence premenstrual syndrome, and to ameliorate migraine headaches. Most of these disorders exclusively or largely afflict women. The lesions of arteries and heart caused by experimental Mg deficiency have been well documented and may contribute to human cardiovascular disease. Estrogen's enhancement of Mg utilization and uptake by soft tissues and bone may explain resistance of young women to heart disease and osteoporosis, as well as increased prevalence of these diseases when estrogen secretion ceases. However, estrogen-induced shifts of Mg can be deleterious when estrogen levels are high and Mg intake is suboptimal. The resultant lowering of blood Mg can increase the Ca/Mg ratio, thus favoring coagulation. With Ca supplementation in the face of commonly low Mg intake, risk of thrombosis increases.

Does a vegetarian diet control Wilson's disease?

Abstract: The literature indicates that copper (Cu) is less bioavailable from a vegetarian as compared to mixed diet. Further, several groups, including ours, find rather marginal average Cu intake in the typical American diet. For example, our data indicate that Wilson's disease patients on a typical American diet ingest only about 25% more Cu than is required. This suggests that a vegetarian diet, if it reduced bioavailability by about 25% or more, would be an adequate maintenance therapy for Wilson's disease. Observations in two of our patients, who were on lactovegetarian diets by choice, and who were almost totally noncompliant with anti-Cu therapy, support this view. These observations suggest that vegetarian diets may be a management tool for Wilson's disease. They also further emphasize the marginal Cu intake in American diets, and suggest that some seemingly healthy people, particularly vegetarians, may be at risk for mild Cu deficiency.

Fatty acids in some common food items in Canada.

Abstract: Fat content and fatty acid (FA) composition of 100 common items in 17 food categories from the Canadian retail market were determined. Of these, 52 samples were made from partially hydrogenated fat. Their fat (in parentheses) and trans FA levels were as follows: breads (3.7% fat) 15.7%, hamburger buns (5.5% fat) 26.3%, cakes (8.7-36.7% fat) 10.1-25.7%, candies/chocolates (27.1% fat) 11.1%, cereals (1.3-12.9% fat) 9.2-33.7%, cookies (5.0-40.5% fat) 7.6-38.7%, crackers (9.2-33.0% fat) 13.8-35.4%, donuts (16.6-29.6% fat) 27.7-32.7%, french fries (pre-cooked) (4.3-4.5% fat) 32.8-42.8%, muffins (12.5-23.7% fat) 16.5-24.2%, pizza crusts (6.0-7.2% fat) 22.1-28.8%, shortenings (100% fat) 17.4-20.2%, potato chips (33.2-40.0% fat) 29.7-39.7%, and corn chips (25.0-34.2%) 29.9-33.9%. Generally the sum of saturated and trans FA in the food items made with partially hydrogenated fat was higher than that of the corresponding food items made with unhydrogenated oils. The higher levels of saturates plus trans were at the expense of the essential fatty acids (EFA). The high-fat foods, such as cakes, cookies, crackers, donuts and potato chips, made with partially hydrogenated fat, were substantially lower in EFA and contained relatively higher levels of trans polyunsaturated fatty acids (PUFA). In some samples of potato chips and french fries, the level of trans PUFA was almost the same or more than the sum of linoleic and linolenic acids.

The effect of acacia gum and a water-soluble dietary fiber mixture on blood lipids in humans.

Abstract: Water-soluble dietary fibers (WSDF) are generally thought to lower cholesterol. This study compared the cholesterol-lowering effects of a medium viscosity WSDF mixture (psyllium, pectin, guar gum and locust bean gum) with an equal amount of WSDF from acacia gum, which has a lower viscosity. Hypercholesterolemic males (n = 13) and females (n = 16) were randomly assigned to one of two WSDF treatments provided in a low-calorie powder form for mixing into beverages (< 4 kcal/serving). Subjects were instructed to mix powders into their usual beverages and to consume them three times daily (5 g WSDF/serving) for 4 weeks while consuming their typical fat-modified diets. Exercise and body weights were also held constant. The WSDF mixture yielded a 10% decrease in plasma total cholesterol (from 251 +/- 20 to 225 +/- 19 mg/dL; p < 0.01), and a 14% reduction in low-density lipoprotein cholesterol (from 167 +/- 14 to 144 +/- 14 mg/dL; p < 0.001). No significant changes in plasma high-density lipoprotein cholesterol, very-low-density lipoprotein cholesterol or triglycerides were observed. In contrast, the acacia gum-treated group showed no change in any plasma lipid parameters. The WSDF treatments did not produce significant changes in mean dietary intakes within or between treatment groups. These data support previous findings that a diet rich in select WSDF can be a useful cholesterol-lowering adjunct to a fat-modified diet, but that caution should be exercised in ascribing cholesterol-lowering efficacy to dietary fibers based solely on their WSDF classification. Finally, WSDF viscosity is a potential cholesterol-lowering factor to be explored further.

Contributions of dietary calcium and physical activity to primary prevention of osteoporosis in females.

Abstract: In the United States and many Western nations, increasing prevalence of osteoporotic fracture is contributing to the health care system burden, and costs and needs for medical services are predicted to increase significantly by the beginning of the 21st century Recent reports investigating developmental changes in skeletal mass of adolescent girls and young women under different experimental or ecological conditions support the contention that modification of environmental factors, especially dietary calcium and physical activity, can favorably modulate bone mass and bone density compared to controls The peripubertal period, starting as early as 10 years of age, seems to be most responsive to modification of environmental/lifestyle factors, whereas potential gains of bone mass during late adolescence and early adulthood, although smaller, may be more readily achieved through improved dietary calcium intakes and regular exercise programs Scientific evidence in support of these beneficial effects on bone is presented as part of the rationale for prevention of osteoporotic fractures Also discussed is the need for a national policy to prevent osteoporosis through primary prevention strategies focused at young girls prior to puberty The goal would be for every prepubertal girl, over the next decade, to achieve peak bone mass (and density) of the spine, hips and other bones by age 20, ie, early adulthood A second target group for national policy should be women in their 20s Attainment of the goal to gain 3-5% additional bone mass during this decade would prolong the time before the fracture threshold range (low bone mass) is reached in the postmenopausal decades

Treatment of Wilson's disease with zinc: XI. Interaction with other anticopper agents.

Abstract: Zinc (Zn) is increasingly being used as a treatment for Wilson's disease. Some physicians have been prescribing Zn in conjunction with other anticopper agents, such as penicillamine or trien, although theoretically these drugs might be antagonistic in their effects. In addition, Wilson's disease patients quite often take vitamin C in high doses in conjunction with Zn therapy, and there are indications of possible interactions among vitamin C, Zn and copper (Cu). Interactions of penicillamine, trien, and vitamin C with Zn have not been previously studied in terms of the potential effects of these agents on Zn efficacy in Wilson's disease. Here we have studied these interactions in the maintenance phase of therapy, using Cu balance and absorption of orally administered 64Cu as endpoints. We find evidence for probable interactions of both penicillamine and trien with Zn; however, the end result on Cu balance is about the same with Zn alone as it is with Zn plus one of the other agents. Thus, there appear to be no advantages to concomitant administration. We find no detectable interaction of Zn and vitamin C on Cu balance, when vitamin C is taken in daily doses of 1000 mg.

Symptom and personality profiles of young adults from a college student population with self-reported illness from foods and chemicals

Abstract: Despite much debate over a presumptively somatic vs psychological etiology of nonatopic food and chemical sensitivities, little systematic research has addressed the issues. The present study investigated self-reported illness from several common foods (wheat, dairy, eggs) and chemicals (pesticide, car exhaust, paint, perfume, new carpet), symptom patterns, and psychological profiles of a sample of young adult college students (n = 490, age 19.4 +/− 2.4, 52% female/48% male). Subjects were divided into 4 groups on the basis of sample medians for frequency of illness from the foods (FI) and chemicals (CI); high FI with high CI (FI/CI), high FI alone, high CI alone, and NOILL (low FI and CI). FI was associated with more defensiveness (denial of negativity) while CI was linked with more shyness (avoidance of novelty). Women outnumbered men in all groups (FI/CI: 61%; FI: 80% CI: 55%) except the NOILL (40% women). Nevertheless, the FI/CI, FI, and/or CI groups still had significantly higher total symptom scores...

Comparison of dietary intake data with guidelines: some potential pitfalls (Dutch nutrition surveillance System).

Abstract: In evaluating dietary data with reference to guidelines for a healthy diet, some potential pitfalls (i.e., method of food consumption assessment and calculation to include or exclude energy derived from alcohol) were investigated. The percentage of energy intake (en%) derived from total fat, saturated fatty acids (SFA), mono- and disaccharides (MD) and intake of cholesterol and dietary fiber per megajoule were calculated using 2-day records obtained in the Dutch National Food Consumption Survey of 1987-1988. Subjects (aged 4-85, n = 5595) were classified into age-sex groups. Mean values and intake distributions were calculated with and without adjustment for within-person variation. Except for the intake of cholesterol and MD, mean intake levels were not in accord with guidelines. About 20% of the women and 23% of the men met the goal for fat intake, 20% of the men and 27% of the women for dietary fiber, and about 60 and 70% for MD and cholesterol. Only 3% of subjects had SFA intake < or = 10 en%, whereas...

Hypothesis: dietary management may improve survival from nutritionally linked cancers based on analysis of representative cases.

Abstract: A limited number of case histories was analyzed and verified to examine the effect of a very low fat, moderately high fiber, and moderately reduced calorie diet on the survival and quality of life of patients with primary cancer of the pancreas, metastatic stage D2 prostate cancer, and other nutritionally linked cancers. The retrospective study of pancreatic cancer patients disclosed that 1-year survival was higher among those who modified their diets than in those for whom there was no evidence as to diet alteration. For patients with metastatic prostate cancer (stage D2), a case control study demonstrated a statistical association of dietary modification with longer survival and improved quality of life. A retrospective study utilizing questionnaires supported such dietary modifications as a useful tool in the management of nutritionally linked cancers.

Errors in estimating peritoneal fluid by bioelectrical impedance analysis and total body electrical conductivity.

Abstract: Whole-body bioelectrical impedance analysis (BIA) and total body electrical conductivity (TOBEC) have been used to estimate body composition and generalized changes in total body water (TBW). The sensitivity of these methods to measure small, rapid, localized changes in body water has not been fully evaluated. We compared the prediction of TBW by whole-body and segmental BIA and TOBEC with deuterium oxide dilution (D2O) in 10 control subjects and 7 renal failure patients receiving continuous ambulatory peritoneal dialysis (CAPD) prior to and after dialysate infusion. Using D2O as the reference method, there was no significant mean residual error between TBW predicted by BIA and TOBEC in controls (−1.2 +/− 1.5 and −0.9 +/− 1.0 kg) and CAPD patients pre-infusion (−1.0 +/− 2.0 and 0.29 +/− 2.01 kg). After infusing 1.9 +/− 0.18 kg dialysate, the mean residual error between change in body weight and the three methods was −0.44 +/− 0.53 kg for D2O (p < 0.1), −1.7 +/− 0.25 kg for BIA (p < 0.0001), and 1.2 +/− 0....

Dietary fat, calories, and the risk of breast cancer in postmenopausal women: a prospective population-based study.

Abstract: We tested the hypothesis that a high-fat diet increases the risk of breast cancer in a population-based study of 590 women aged 40-79 years who were without known breast cancer when they provided a quantitative 24-hour diet recall. Fifteen postmenopausal women were diagnosed with incident breast cancer during the next 15 years (approximately 7600 person-years of follow-up). These women had significantly higher age-adjusted intake of all fats (monounsaturated, polyunsaturated, and saturated), and oleic, linoleic, and linolenic acids, with a stepwise increase in risk across tertiles of intake. Fat intake was associated with total calories, protein, and carbohydrates, and women with incident breast cancer consumed more calories, protein, and carbohydrates than did other subjects. When each nutrient variable (calories, fats, protein, and carbohydrates) was adjusted for age, body mass index, age at menopause, parity, and alcohol consumption, the strongest risks for incident breast cancer were associated with total calories (relative risk per standard deviation = 2.72, 95% confidence interval = 1.51-4.89, p = 0.002) and total fats (relative risk per standard deviation = 2.01, 95% confidence interval = 1.19-3.41, p = 0.01). Fat composition of the diet, expressed either as percent of energy or as fat intake adjusted for calories by regression analysis, was not significantly associated with risk of breast cancer. These results support the hypothesis that total calorie consumption, as well as dietary fat consumption, is a risk factor for breast cancer in postmenopausal women, and parallel observations in animal models.

Renal excretion of ascorbic acid: effect of age and sex

Abstract: To determine if the lower plasma ascorbic acid concentrations observed in males compared to females, and in the elderly in general, might be due to differences in renal clearances of ascorbic acid, tubular maximum reabsorptions (TmAA) and renal thresholds for ascorbic acid were determined on older (10 male, 10 female, aged 70-86 years) and younger (3 male, 5 female, aged 26-59 years) subjects. The mean TmAA for men was 1.54 +/- 0.29 and for women 1.39 +/- 0.33 mg/minute/100 mL glomerular filtration rate (p > 0.05). The mean renal threshold for men was 1.51 +/- 0.25 and for women 1.26 +/- 0.16 mg/dL (p < 0.02). Neither was affected by age. If differences in TmAA and renal threshold were to explain the lower plasma ascorbic acid concentrations observed in males, both values should have been lower than in females. The ability of women to maintain higher plasma ascorbic acid concentrations than men, and young higher than elderly, cannot be explained by differences in the renal handling of ascorbic acid.

Regulation of iron absorption: proteins involved in duodenal mucosal uptake and transport.

Abstract: Newly identified iron (Fe)-binding proteins isolated from both rat and human duodenal mucosa permit a better understanding of Fe absorption. Mucins bind Fe at acid pH to keep it soluble and available for absorption at the more alkaline pH of the duodenum; this explains the development of Fe deficiency in achlorhydric subjects. Integrin was identified on the surface of enterocytes in association with radioiron and is believed to facilitate the transfer of Fe through the microvillous membrane. Mobilferrin, a 56 kDa Fe-binding protein, was identified in enterocyte cytosol. It coprecipitates with integrin and appears in close association with integrin in the apical cytoplasm of absorptive cells. We postulate it accepts dietary Fe from integrin and acts as the shuttle protein from Fe in the cytoplasm. Since Fe in enterocytes remains in equilibrium with body stores, we postulate mucosal Fe uptake is regulated by the number of Fe-binding sites either occupied or unoccupied by Fe on mobilferrin. Fe repletion of e...

Brief communication: dietary habits of first-year medical students as determined by computer software analysis of three-day food records.

Abstract: Nutrition training for medical students has long been a low priority for most medical schools. Given the growing body of knowledge linking health promotion to proper dietary habits, there is a need to increase the quantity and quality of nutrition training for medical students. In the present study, first-year medical students recorded food intake for 3 days and analyzed their diets for nutrient contents with a computer software program. Use of the interactive software created a personalized approach to increasing nutrition knowledge as the students became aware of their own dietary habits. Female students had a low consumption of kilocalories, dietary fiber, calcium, iron, zinc, potassium, and polyunsaturated fat. Male students exceeded current recommended intakes for fat, saturated fat, cholesterol, and sodium.

Effects of gestation, lactation, and maternal calcium intake on mechanical strength of equine bone.

Abstract: Skeletal homeostasis during late gestation, lactation, and the post-lactational recovery period is poorly understood. In an experiment using an animal model (the horse), metacarpal breaking strengths (MBS) estimated via transmission ultrasonics were examined during the last 12 weeks of gestation and for 40 weeks after parturition. MBS increased during the last 6-10 weeks of gestation in mares fed amounts of calcium (Ca) recommended by the National Research Council; maximum MBS coincided with the week of parturition. In contrast, MBS in mares fed 20% less Ca remained relatively constant during the last 12 weeks of gestation. In contrast to increases during late gestation, MBS decreased steadily in all mares during the first 12 weeks of lactation. MBS increased after approximately 12 weeks of lactation, but more slowly than they had declined. MBS of the bones of mares fed recommended amounts of Ca were fully restored at 24 weeks post-parturition, but those of Ca-deficient mares had not fully recovered even ...

Dysprosium as a nonabsorbable marker for studies of mineral absorption with stable isotope tracers in human subjects.

Abstract: Two studies were conducted to determine if dysprosium (Dy) could be used as a quantitative fecal marker for studies of zinc-70 (70Zn), copper-65 (65Cu) and magnesium-26 (26Mg) absorption in humans. In the first experiment, Dy excretion was shown to be complete (104 +/− 9%; mean +/− SD, n = 6) and the kinetics of fecal Dy excretion closely paralleled that of 70Zn but not 65Cu. Because of the similarity in 70Zn and Dy excretion kinetics, a method for estimating 70Zn absorption was developed which used 70Zn and Dy data from only the first two stools passed after isotope administration. Average estimates of 70Zn absorption based on the two-stool (partial pool) vs total pool (5-day composite) method were not different (28.0 +/− 5.2 vs 24.4 +/− 4.1%, respectively; means +/− SEM; p > 0.10). In the second study, the same questions was addressed relative to 26Mg absorption. 26Mg and Dy also exhibited nearly identical excretion patterns. Average estimates of 26Mg absorption based on the partial pool vs total pool m...