Dietary intake as a risk factor for cancer of the exocrine pancreas.

Data from 149 cases with pancreatic cancer and 363 control subjects in Utah were obtained from proxy respondents to assess the associations between dietary intake and the development of pancreatic cancer. After adjusting for cigarette smoking status and alcohol and coffee consumption, we observed that foods containing large amounts of fat from all sources increased risk of pancreatic cancer in men [odds ratio (OR), 3.41; 95% CI, 1.59-7.29]. Further division of fat by source of food showed that high intake of bacon and sausages (OR for upper tertile, 2.77; 95% CI, 1.34-5.72) as well as large intakes of fatty foods other than meat or dairy products (OR for upper tertile, 2.80; 95% CI, 1.33-5.89) increased risk of pancreatic cancer in men; high levels of intake of red meat, chicken, fish, and dairy foods did not increase risk of pancreatic cancer in either men or women. In women, fat from nonmeat and nondairy sources also increased risk of pancreatic cancer (OR for upper tertile, 3.44; 95% CI, 1.35-8.78). Although no protective effect was observed among men who consumed large amounts of fruits, vegetables, or high fiber foods, we did observe a protective effect in women for these foods (OR for upper tertile of fruit consumption, 0.37; 95% CI, 0.18-0.81; OR for upper tertile of vegetable consumption, 0.32; 95% CI, 0.13-0.74; and OR for upper tertile of fiber consumption, 0.28; 95% CI, 0.12-0.67). Findings from this study support the hypothesis that diets high in fat contribute to the development of pancreatic cancer.(ABSTRACT TRUNCATED AT 250 WORDS)

Gastric acid production, iron status and dietary phytate alter enhancement by meat of iron absorption in rats.

This study was designed to determine whether gastric acidity, added phytate or iron status significantly influenced the effects that dietary proteins have on iron absorption. Rats were fed test meals of wheat cereal, with and without an added dietary protein (beef, pork, chicken, fish or egg white), by gavage. The influences of phytate and gastric acid were investigated by adding sodium phytate to the test meals and by treating the rats with cimetidine to inhibit gastric acid production. Iron status was altered by dietary regimens. Significant (P < 0.05) effects of the proteins were determined by comparison of the various protein-containing meals to control meals of cereal or cereal + phytate, as appropriate. Gastric acidity, phytate and iron status were all confirmed as factors significantly affecting iron absorption. Beef, pork and chicken enhanced iron absorption, but only when phytate had been added to the meals and only in iron-deficient rats. Enhancement by meat was sufficient to overcome the inhibition by phytate. Fish was an inhibitor or enhancer in cimetidine-treated, iron-deficient rats, depending on the absence or presence of phytate, respectively. Egg white inhibited absorption from cereal meals in cimetidine-treated, iron-deficient rats.

Effect of coprophagy on bioavailability of iron from plant foods fed to anemic rats.

Effects of coprophagy and coprophagy preventing device on iron bioavailability were evaluated in two experiments. In Experiment 1, rats were fed diets with FeSO4, spinach, bran cereal or cornmeal as the iron source. The rats in each diet group were fitted with collars, sham-collars or not fitted with collars (control). In Experiment 2, rats were fed diets with FeSO4 or green peas as the iron source and were fitted with collars, tail cups, sham-collars or not fitted with any device (control). Preventing coprophagy reduced hemoglobin regeneration efficiency (HRE) of rats fed bran cereal, green peas, spinach or cornmeal diets by 26 (P less than .05), 24(P less than .05), 22(P less than .05) and 11% (not significant), respectively. Preventing coprophagy in rats fed FeSO4 diet did not significantly reduce HRE. Sham-collaring reduced (P less than .05) HRE of rats fed the FeSO4 diet by 12 and 13% but did not significantly affect HRE in rats fed food iron sources. It was more convenient and effective to prevent coprophagy with collars than with tail cups. Differences in bioavailability between food and FeSO4 iron due to coprophagy may be explained based on two gastrointestinal nonheme iron pools, complexed and highly soluble.

Coffee consumption and the risk of cancer of the exocrine pancreas: a case-control study in a low-risk population.

Data from a population-based, case-control study of 149 cases of cancer of the exocrine pancreas (excluding insulinomas) and 363 controls were used to test the hypothesis that coffee consumption increased the risk of cancer of the exocrine pancreas. Because of the high mortality from cancer of the pancreas, all information was obtained from proxy respondents for cases and controls. Increased risk was present for coffee drinkers [odds ratio (OR) = 2.38], cigarette smokers (OR = 2.27), and alcohol users (OR = 1.60), but the effect for alcohol disappeared after adjustment for cigarette use. Risk increased with the amount of coffee drunk with an OR of 2.38 in the those having at least 50,000 lifetime cups. This gradient was present in both men and women, and in cigarette smokers and nonsmokers. Increased risk was present for users of regular and decaffeinated coffee, but the risk was higher for users of decaffeinated coffee than users of regular coffee. Cigarette smoking, after controlling for coffee consumption, was an independent risk factor for pancreatic cancer, with odds ratios in the heaviest smokers of 2.71 (95% confidence interval = 1.41-5.21.

Contributions of heme and nonheme iron to human nutrition.

Dietary iron is present in food both in inorganic forms as ferrous and ferric compounds, and in organic forms, the most important of these being heme iron. The purpose of this review is to evaluate the contributions of both heme and nonheme iron in establishing and maintaining a healthful iron status. The human requirement for iron, bioavailability of heme and nonheme iron, and amounts of heme and nonheme iron in the diet are individually estimated after reviewing the relevant literature in Sections II, III, and IV, respectively. In Section V, the contribution of heme and nonheme iron to human nutrition, as compared to the human requirement for iron (Section II), is estimated after attenuating the amounts of heme and nonheme iron found in the diet (Section IV) by their bioavailabilities (Section III).

Determination of iron absorption by rat bioassay. Evaluation of methods of dosing 59Fe on radioiron absorption from plant diets.

We studied the potential of an animal model to predict nonheme iron absorption in humans and tested a feasible and easy technique of dosing 59Fe to evaluate bioavailability of dietary nonheme iron. Plant diets containing about 20 ppm or 75 ppm iron were the nonheme iron sources with ferrous sulfate (75 ppm) as a reference. Radioiron was administered by (a) gavaging in water, 1 h after a meal; (b) mixing with the meal; and (c) making a slurry with the meal and gavaging. No significant differences were found (P less than or equal to 0.05) in 59Fe absorption among the three methods of administering radioiron. Absorption of 59Fe was similar to apparent iron absorption for all diets tested, whether the animals consumed the same diet as that of the test meal or a different diet. A high correlation (r = 0.88) obtained between the apparent iron absorption and 59Fe iron absorption for different dosing techniques, indicates that extrinsic iron tag administered by any of these methods is valid to measure nonheme iron absorption. Apparent iron absorption values determined by rats fed 20 ppm or 75 ppm dietary iron from plant sources were similar to reported values for humans. It is concluded that the normal adult rat is an appropriate model to study iron bioavailability of human foods when iron status, maturity, iron intake relative to requirement, and method of measurement are similar to the human situation.

Adult dietary intake and prostate cancer risk in Utah: a case-control study with special emphasis on aggressive tumors.

A population-based case-control study in Utah of 358 cases diagnosed with prostate cancer between 1984 and 1985, and 679 controls categorically matched by age and county of residence, were interviewed to investigate the association between dietary intake of energy (kcal), fat, protein, vitamin A, beta-carotene, vitamin C, zinc, cadmium, selenium, and prostate cancer. Dietary data were ascertained using a quantitative food-frequency questionnaire. Data were analyzed separately by age (45-67, 68-74) and by tumor aggressiveness. The most significant associations were seen for older males and aggressive tumors. Dietary fat was the strongest risk factor for these males, with an odds ratio (OR) of 2.9 (95 percent confidence interval [CI] 1.0-8.4) for total fat; OR = 2.2 (CI = 0.7-6.6) for saturated fat; OR = 3.6 (CI = 1.3-9.7) for monounsaturated fat; and OR = 2.7 (CI = 1.1-6.8) for polyunsaturated fat. Protein and carbohydrates had positive but nonsignificant associations. Energy intake had an OR of 2.5 (CI = 1.0-6.5). In these older men, no effects were seen for dietary cholesterol, body mass, or physical activity. There was little association between prostate cancer and dietary intake of zinc, cadmium, selenium, vitamin C, and beta-carotene. Total vitamin A had a slight positive association with all prostate cancer (OR = 1.6, CI = 0.9-2.4), but not with aggressive tumors. No associations were found in younger males, with the exception of physical activity which showed active males to be at an increased but nonsignificant risk for aggressive tumors (OR = 2.0, CI = 0.8-5.2) and beta-carotene which showed a nonsignificant protective effect (OR = 0.6, CI = 0.3-1.6). The findings suggest that dietary intake, especially fats, may increase risk of aggressive prostate tumors in older males.

Protein quality and iron bioavailability of mechanically and hand-deboned turkey meat fed to rats.

The protein quality and iron bioavailability of mechanically deboned turkey meat (MDT) and hand-deboned turkey meat (HDT) were determined in rats. The protein, fat, and moisture levels in MDT were similar to those found in HDT. The MDT, however, contained more ash, calcium, and iron than the HDT. The MDT and HDT had similar amino-acid patterns; methionine and cystine were the limiting amino acids for both products. The amino-acid scores were .97 and .98 for MDT and HDT, respectively. The protein efficiency ratio and biological value as well as the values for net protein utilization and nitrogen efficiency for growth for MDT were similar to those for HDT and reference casein (P greater than .05). The hemoglobin-regeneration efficiency values were 40, 39, and 55%, respectively, for MDT, HDT, and FeSO4 (least significant difference = 12%). The MDT contained more bioavailable iron (7.6 mg of iron per kg of meat or 4.1 mg of iron per 1,000 kcal) than the HDT (4.2 mg/kg or 2.4 mg/1,000 kcal). Mechanically deboning turkey meat did not affect its protein quality, but increased the amount of bioavailable iron.

Dietary intake and colon cancer: sex- and anatomic site-specific associations.

A case-control study was conducted in Utah between July 1979 and June 1983 in which 231 cases of colon cancer identified through the Utah Cancer Registry and 391 controls identified through random digit dialing were interviewed. Odds ratios (OR) were calculated comparing the highest exposure categories with the lowest exposure categories. The highest quintile of body mass index (weight (kg)/height (m)2 for males; weight (kg)/height (m)1.5 for females) was associated with increased risk in both males (OR = 2.1) and females (OR = 2.3). In females, total dietary fat (OR = 1.9) and energy intake (OR = 1.5) were associated with an increased colon cancer risk after adjusting for age, body mass index, and crude fiber. Fiber was protective in females (OR = 0.5) after adjusting for age, body mass index, and energy intake, as was beta-carotene (OR = 0.5) after also adjusting for crude fiber. Adjusted risk estimates in males were 2.0 for total dietary fat, 3.8 for polyunsaturated fat, 2.1 for monounsaturated fat, 2.1 for energy intake, 2.5 for protein, 0.3 for fiber, 0.4 for beta-carotene, and 0.3 for cruciferous vegetables. Risk estimates differed by site of cancer within the colon. In males, protein (OR = 3.8) was a risk factor for cancer of the descending colon, while fats (OR = 2.7-8.8) increased the risk of cancer of the ascending colon. The hypotheses that dietary fat increases colon cancer risk while dietary fiber decreases colon cancer risk and that fat and protein may be independently associated with colon cancer risk are supported.

Bioavailability of iron-milk-protein complexes and fortified cheddar cheese.

Iron fortification is used to increase dietary iron intake. Dairy products are widely consumed but contain almost no iron. Cheddar cheese was fortified with ferric chloride or iron-casein, ferripolyphosphate-whey protein, and iron-whey protein complexes. Hemoglobin regeneration efficiency was determined to evaluate iron bioavailability. Maximal and basal iron bioavailabilities were measured in anemic weanling rats fed low iron diets (about 22 mg iron/kg) and normal adult rats fed high iron diets (about 145 mg iron/kg) of iron density (32 mg iron/1000 kcal) found in some high iron human diets. Maximal iron bioavailabilities for ferric chloride or iron-casein, ferripolyphosphate-whey protein, and iron-whey protein complexes were 85, 71, 73, and 72%, respectively, and for the respective iron-fortified cheeses they were 75, 66, 74, and 67%. Differences were not significant in maximal iron bioavailabilities among iron sources and between fortified cheeses and fortification iron sources. Basal iron bioavailabilities for 10-d feeding of the respective fortification iron sources were 5, 8, 6 and 7%, respectively, and 4, 4, 3, and 3% for 14 d feeding; the differences among the iron sources were not significant. Maximal and basal iron bioavailabilities of ferrous sulfate were 85 and 5%, respectively. Practical implications of these observations are discussed.

Proteolytic digestion of meat is not necessary for iron solubilization.

The effects of digested cooked or raw meat and nondigested cooked or raw meat on iron solubility were investigated in vitro. Experiment 1 involved adding iron to meat slurries followed by in vitro digestion using pepsin and then pancreatin. Pepsin and pancreatin were excluded from incubation mixtures used as the nondigested treatment. Ferric iron in aqueous solution was used as an iron-only control. Dialyzable iron for each treatment was determined by measuring iron able to cross a dialysis membrane having a molecular weight cut-off of 6,000-8,000. Soluble iron was determined as that iron remaining in solution after centrifugation at 2,500 x g for 15 min. No differences (P greater than 0.05) in dialyzable iron were observed between treatments. However, soluble iron in the digested meat treatments was greater than soluble iron in the nondigested treatments (P = 0.05) or iron-only controls (P = 0.01). There was no difference (P greater than 0.05) between nondigested and iron-only treatments. In experiment 2, meat components were first separated by dialysis from digested or nondigested meat. The pH of the isolated components was adjusted to 2.0, iron added, and the pH adjusted to 7.0. Dialyzable and soluble iron were then determined. As in experiment 1, no differences (P greater than 0.05) in dialyzable iron among treatments were observed. Dialyzable components from digested or nondigested meat increased soluble iron as compared to the iron-only control (P = 0.01), with soluble iron values for the nondigested treatment being greater (P = 0.01) than for the digested treatment. Thus, meat contains a factor(s) that solubilizes iron independent of proteolytic digestion.

Bioavailability of total iron from meat, spinach (Spinacea oleracea L.) and meat-spinach mixtures by anaemic and non-anaemic rats.

1. Bioavailability of Fe from beef, spinach (Spinacea oleracea L.) and their mixtures was studied using anaemic and non-anaemic rats by haemoglobin regeneration efficiency (HRE) and apparent Fe absorption in two trials. 2. The initial haemoglobin levels of severely anaemic, mildly anaemic and non-anaemic rats were 63, 88 and 113 g/l, respectively. The Fe level in diets was about 30 mg/kg. All other nutrients equalled or exceeded the requirement of the growing rat. 3. The spinach Fe was well utilized by the rats with average HRE of 0.41, 0.53 and 0.36, and apparent Fe absorptions averaging 0.48, 0.59 and 0.37 for the severely anaemic, mildly anaemic and non-anaemic animals respectively. 4. Beef Fe was efficiently used by rats as reported by others. Average HRE were 0.42, 0.51 and 0.44, and average apparent Fe absorptions were 0.44, 0.47 and 0.46 for the severely anaemic, mildly anaemic and non-anaemic rats respectively. 5. When the percentage of meat Fe was increased from 0 to 25, 50, 75 or 100 of the dietary Fe, HRE and apparent Fe absorption were not increased significantly. A meat enhancement effect on total Fe absorption, reported by others for non-haem-Fe, did not occur in the present experiment. 6. Negative correlation coefficients between initial haemoglobin and HRE (r -0.79), and initial haemoglobin and apparent Fe absorption (r -0.73) were seen with the rats fed on dietary Fe from FeSO4.7H2O. This was not seen with the rats fed on dietary Fe from beef or spinach. 7. The Fe absorption pattern for the different Fe sources is evidence for a third Fe pool, a pool made up of highly soluble inorganic Fe salt, in addition to haem-Fe and non-haem-Fe complex pools. FeSO4.7H2O is not in the same gastrointestinal pool as non-haem-Fe complex such as spinach Fe. A suggested mechanism of absorption is discussed.

Diet and colon cancer: assessment of risk by fiber type and food source.

How fiber in the diet is related to the development of colon cancer was assessed in a population-based study conducted on 231 cases and 391 controls in Utah between 1979 and 1983. Crude fiber consistently decreased risk associated with colon cancer in both males [odds ratio (OR) = 0.4] and females (OR = 0.5). Dietary fiber, as analyzed by the method of A. S. Bitner, and neutral detergent fiber were not consistently related to colon cancer risk. Of the noncellulose polysaccharides examined, mannose and galactose were protective against cancers in the ascending colon in males (ORs = 0.5 and 0.3, respectively), whereas galactose and uronic acid were protective against cancers in the ascending colon in females (ORs = 0.5). Highest quartiles of intake of fruits and vegetables were also associated with a decreased risk of colon cancer in males (ORs = 0.3 and 0.6, respectively) and in females (ORs = 0.6 and 0.3, respectively) compared with lowest quartile of intake, whereas high intake of grains was not protective.

Fried foods and the risk of colon cancer.

High-temperature cooking of foods produces a variety of mutagenic substances. Because of the association of such substances with carcinogenesis, the authors used a case-control study of colon cancer conducted in Utah between 1977 and 1979 with 246 cases and 484 controls to test the hypothesis that persons with colon cancer would report more frequent use of fried and broiled meats. Intake of food was measured by a food frequency questionnaire which focused on food use five years before the interview. For men, the odds ratios for the highest level of use were 1.2 (90% confidence interval (CI): 0.8-1.9) for fried meats and 0.7 (90% CI: 0.5-1.0) for broiled meats; for women, the odds ratios were 1.3 (90% CI: 0.8-2.1) for fried meats and 1.1 (90% CI: 0.7-1.7) for broiled meats. The reported use of fried and broiled vegetables was too infrequent to permit evaluation. The authors conclude that the ingestion of fried and broiled meats five years before diagnosis of colon cancer had little influence on the development of this cancer.

Dietary calcium and phosphorus and seizure susceptibility of magnesium deficient rats.

Convulsions are characteristic of magnesium deficiency and hypocalcemia. In this study, weanling rats were fed magnesium deficient diets with varying concentrations of calcium and phosphorus. Diets were either normal (Mg =) or low (Mg-) in magnesium and were either low (Ca- or P-), normal (Ca = or P =) or high (Ca+ or P+) in calcium or phosphorus. After consuming the diets for 17 days, the rats were tested for audiogenic seizures and blood was then drawn for serum mineral analyses. Rats fed Mg-Ca = P =, Mg-Ca = P-, Mg-Ca+P = or Mg-Ca+P+ diets had high incidences of seizures. Those fed Mg-Ca-P =, Mg-Ca-P-, Mg-Ca = P+, Mg-Ca-P+ or Mg-Ca+P- diets had low incidences of seizures. In general, animals with low serum magnesium and calcium levels and high serum potassium levels were susceptible to audiogenic seizures. In this model, serum magnesium level is the most important determinant of seizure susceptibility, followed by calcium and potassium.

Energy intake: its relationship to colon cancer risk.

A case-control study was conducted to assess the role of diet in the etiology of colon cancer. Diet was measured by means of a comprehensive quantifiable food frequency history instrument in 246 cases and 484 controls drawn from the general population of Utah. Each subject's diet was described by major nutrient groups and total energy based on the nutritional content of foods reported. Cases reported higher daily food intake 5 years preceding diagnosis than controls [men, rate ratio (RR) = 2.5; women, RR = 3.6], as measured by total energy content of the diet. Higher risk of colon cancer with increasing energy intake was independent of stage of disease at diagnosis and obesity, as measured by body mass. Fat, protein, and carbohydrate intake all had elevated RRs but could not be assessed as risk factors independent of energy intake because of their strong correlations with total calories. Due to the higher energy intake of the cases, odds ratios for the daily intake of dietary fiber and vitamins A and C were also greater than 1. However, adjusting for caloric intake removed this effect, and dietary fiber showed a weak protective effect. Total energy intake must be evaluated before attempting to assign a causal role to any food or nutrient that may be postulated to play a role in colon cancer.

Adult dietary characteristics affecting iron intake: a comparison based on iron density.

Food frequency information from 762 Utahns, aged 24 to 80 years, selected from the general population using a random digit dialing technique was studied to determine the characteristics of diets that provide 18 mg iron/2,000 kcal, the Recommended Dietary Allowances (RDAs) of iron and energy for women aged 23 to 50 years. The diets were divided into three categories according to iron per 1,000 kcal: category 1, 9.0 mg or more iron; category 2, 6.0 to 8.99 mg iron; and category 3, 5.99 mg or less iron. Twenty-seven percent of the women and 16% of the men reported consuming diets containing more than 9 mg iron/1,000 kcal. Six percent of the women consumed 18 mg iron daily. Total energy intake decreased dramatically as iron density increased, as did intake of protein, carbohydrate, and fat. However, the percentage of energy consumed as protein and carbohydrate increased in the high-iron density categories. Individuals in the high-iron density categories consumed greater proportions of their iron and energy from vegetable, fruit, and cereal products; those in the low-iron density category consumed more pastries, beverages, sweets, and added fats, i.e., high-calorie foods. When fortified breakfast cereals were removed from the diets, only 14% of the women and 6% of the men consumed diets that provided at least 9 mg iron per 1,000 kcal. Women can meet the RDA for iron from their diets if they consume the recommended amount of energy distributed across food groups as follows: cereals, 14% to 16%; vegetables, at least 11%; meat, fish, poultry, and eggs, 16% to 18%.(ABSTRACT TRUNCATED AT 250 WORDS)

Bioavailability of iron in goat milk compared with cow milk fed to anemic rats.

Bioavailabilities of iron from dehydrated whole and skim goat milk were investigated using iron-deficient rats. Hemoglobin regeneration efficiencies were determined as the percent conversion of dietary iron into hemoglobin. The respective hemoglobin regeneration efficiencies for groups fed whole goat milk, whole cow milk, skim goat milk, and skim cow milk were 50.6, 13.1, 26.0, and 13.0%, indicating that iron bioavailability of goat milk was greater than cow milk. However, rats fed each milk had negative net increases in hemoglobin concentrations, implying that the iron contents of each milk were not adequate. For animals consuming whole goat milk supplemented with ferrous sulfate, the slope relating hemoglobin iron gained versus iron intake was .95. Respective bioavailabilities relative to ferrous sulfate were 54, 14, 28, and 14% for the four sources of milk. Iron bioavailability of goat milk is superior to cow milk when fed to anemic rats.

Effect of iron-deficiency anemia on percent blood volume in growing rats.

In determining iron bioavailability as iron gained in hemoglobin relative to intake, blood volume is calculated for the iron-deficient animals at the initiation of a feeding trial and again on the iron-repleted animals at the termination of the trial. However, the effect of iron deficiency on percent blood volume in the rats commonly used in iron repletion studies has not been determined. In experiment 1, we noted the relationship between body weight and blood volume in 18 randomly selected healthy male rats with a weight range of 95-278 g. In experiment 2, the in vivo disappearance of Evans blue dye from the plasma of 17 rats and the precision of the dye dilution method for estimating known volumes of heparinized rat blood were studied. From this information, linear regression equations were developed to more accurately estimate blood volume in vivo. In experiment 3, we studied blood volume relative to body weight in 122 weanling male rats at four levels of anemia. These animals were fed a low iron diet and bled to achieve anemia in 7 days. In the subsequent repletion interval, the rats were fed diets supplemented with ferrous sulfate for periods of 0, 5, 10 or 15 days, after which hemoglobin and blood volume were determined, and the animals were killed. Though body weight and blood volume were linearly correlated (r = 0.78), no such association existed between body weight and percent blood volume (r = 0.058). Blood volume held constant at 7.5 +/- 0.1 (mean +/- SE) percent of body weight in weanling prepubescent rats of 30-45 days of age regardless of iron status.