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.

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.

Nutritional assessment of senior rural Utahns by biochemical and physical measurements.

Biochemical composition of blood and urine was used to evaluate the nutritional status of 187 ambulatory, older residents of five rural Utah communities. Measurements were also taken of height, weight, and blood pressure. The sample included 58 men and 129 women, with a mean age of 69 years. No deficiencies were observed for hemoglobin, hematocrit, and serum iron levels, although approximately 15% of the men had low levels for the first two indices. Serum mineral status for zinc, copper, sodium, potassium, magnesium, and calcium was adequate for most of the participants. Of the women 40% and of the men 21% had low serum total protein levels. No low serum levels of vitamin A and carotene were observed. Urinary excretion of riboflavin and thiamine was high for approximately 90% of the participants. Of the women 46% and of the men 37% had serum cholesterol values above 249 mg/100 ml of serum. One half of the women and 30% of the men were determined to be obese. Approximately one-fourth of both sexes had systolic pressures above 160 mm Hg.

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)

Utilization of dietary calcium by iron-deficient rats.

Iron deficiency causes cytological and enzymic changes in the gastrointestinal mucosa of animals and man that can be expected to impair the digestion and absorption of other nutrients. In experiment 1, healthy, weanling, female rats were grouped into pair-mates and pair-fed either an iron-deficient or an iron-supplemented diet for 19 weeks. In experiment 2, iron-deficient offspring reared by iron-deficient females were grouped into pair-mates and pair-fed either an iron-deficient or an iron-supplemented diet for 15 weeks. In experiment 1, apparent absorption of calcium was significantly depressed in week 9 (p less than 0.001) and slightly depressed in weeks 10 and 11. In experiment 2, the apparent absorption of calcium was significantly (p less than 0.001) depressed in weeks 6, 13, and 14. Absorption was not measured in other weeks in these experiments. The concentrations of calcium and magnesium were consistently higher in the fecal dry matter of the iron deficient rats in both experiments. It was concluded that any defects in digestion and absorption by the iron-deficient rats was confined primarily to the mineral nutrients because in both experiments apparent absorption of dry matter was consistently higher in these animals compared to their iron-supplemented pair-mates.

Effect of dietary iron level on efficiency of converting food iron into hemoglobin by the anemic rat.

The effects of varying the dietary levels of ferrous sulfate or ferric orthophosphate on the efficiency of the conversion of dietary iron into hemoglobin iron, was evaluated with the anemic rat. Weanling male rats were made anemic by feeding a semipurified diet containing 8.4 mg iron/kg, and by bleeding. They were divided into nine groups so that hemoglobin levels and body weights were similar. The rats were fed the basal diet or basal diet plus 12, 24, 36 and 48 mg iron/kg diet provided as ferrous sulfate or ferric orthophosphate. The rats were fed 10 g daily of the respective diets for 10 consecutive days. The efficiency of the conversion of dietary iron into hemoglobin iron was not significantly affected by dietary level of either iron salt. It was determined that ferric orthophosphate was 51% as efficient as ferrous sulfate for hemoglobin regeneration in the anemic rat.

Effects of calcium solubility on adsorption by rats with induced achlorhydria.

Gastric X-irradiated, achlorhydric rats and sham-operated controls were fed diets containing very soluble calcium chloride or calcium gluconate or slightly soluble calcium carbonate or tricalcium phosphate for 3 weeks. Calcium was absorbed more efficiently by achlorhydric rats from the very soluble salts from the slihtly soluble salts. The control rats absorbed calcium from the very soluble and slightly soluble calcium salts with similar efficiency. Achlorhydric rats fed slightly soluble calcium salts developed weaker bones with a lower mineral content than did those fed very soluble calcium. Apparently, the very soluble dietary calcium offset the impaired calcium absorption of achlorhydric rats. Calcium solubility had no significant effect on the bones of control animals.

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)

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.

Effects of cerebral intraventricular magnesium injections and a low magnesium diet on nonspecific excitability level, audiogenic seizure susceptibility and serotonin.

Cerebral intraventricular injections of 17 and 50 microgram magnesium in artificial cerebrospinal fluid progressively depressed the Non-specific Excitability Level of permanently cannulated 150--200 g rats fed a low magnesium diet for 21 days. Compared with control diet, a low Mg diet caused an increase in brain serotonin. Weanling rats fed a low Mg diet for 2 weeks, then injected with 25 microgram Mg via acute cannulations, displayed reduced audiogenic seizure susceptibility compared with sham-injected controls.

Fasting and ketogenic diet effects on audiogenic seizures susceptibility of magnesium deficient rats.

Because fasting and ketogenic diets decrease seizure susceptibility in epileptics, their anticonvulsant effects were studied using sound-induced seizures in the magnesium-deficient rat. Fasting markedly depressed seizure incidence and severity but did not affect latency (sec to seizure onset). High-fat diet increased incidence of audiogenic seizures and seizure severity, and decreased latency. Gavage of medium chain triglyceride, beta-hydroxybutyrate or glucose did not affect seizure incidence, seizure severity or latency. Nonspecific excitability level was not associated with treatment nor with seizure incidence, severity or latency time.

Effect of magnesium deficiency on nonspecific excitability level (NEL) and audiogenic seizure susceptibility.

Magnesium deficiency in weanling rats caused an increase in NEL and in audiogenic seizure susceptibility. These behavioral effects were apparent after eight days of magnesium restriction and could be reversed by dietary rehabilitation. Serum magnesium declined rapidly from 1.87 +/- 0.10 mEq/L to 0.91 +/- 0.24 mEq/L in two days. Cerebrospinal fluid (CSF) magnesium decreased gradually from 1.86 mEq/L, becoming significantly lower (1.44 +/- 0.23 mEq/L) after eight days. When deficient rats were injected IP with MgCl2, raising the serum magnesium concentration to 6.6 mEq/L, NEL decreased to normal while audiogenic seizure susceptibility remained. Both NEL and audiogenic seizure susceptibility in rats reflect central nervous system magnesium concentration, except when serum magnesium concentration is very high. Very high serum magnesium concentration lowers NEL but does not reduce audiogenic seizure susceptibility if CSF magnesium is low.

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.

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.

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.

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).