北京市郊区青春期少年植酸摄入量及其与钙铁锌的摩尔比值研究

目的通过调查农村青春期少年植酸的摄入量及其与钙、铁、锌的摩尔比值,评价其植酸摄入水平,为改善青少年对矿物质的吸收利用提供依据。方法随机选取北京市怀柔区某学校11～16岁中学生304人(男154人、女150人),采用连续3d24h回顾法进行膳食调查,并根据不同食物含量计算植酸及钙、铁、锌的摄入量。结果农村青春期少年植酸摄入量为620.5mg/d(男生670.0mg/d,女生569.6mg/d),性别差异有统计学意义(P<0.05)。植酸与钙、铁、锌的摩尔比值分别为0.1、2.1、4.4,植酸×钙/锌为34.9,性别差异无统计学意义。结论农村青春期少年植酸摄入量低于2002年全国平均水平和其他发展中国家水平,但高于西方发达国家水平,其摄入量可能会影响机体对钙、铁、锌的吸收。     

Phytate intake and molar ratios of phytate to zinc, iron and calcium in the diets of people in China

OBJECTIVE: To assess the phytate intake and molar ratios of phytate to calcium, iron and zinc in the diets of people in China. DESIGN: 2002 China Nationwide Nutrition and Health Survey is a cross-sectional nationwide representative survey on nutrition and health. The information on dietary intakes was collected using consecutive 3 days 24 h recall by trained interviewers. SUBJECTS: The data of 68 962 residents aged 2-101 years old from 132 counties were analyzed. RESULTS: The median daily dietary intake of phytate, calcium, iron and zinc were 1186, 338.1, 21.2 and 10.6 mg, respectively. Urban residents consumed less phytate (781 vs 1342 mg/day), more calcium (374.5 vs 324.1 mg/day) and comparable amounts of iron (21.1 vs 21.2 mg/day) and zinc (10.6 vs 10.6 mg/day) than their rural counterparts. A wide variation in phytate intake among residents from six areas was found, ranging from 648 to 1433 mg/day. The median molar ratios of phytate to calcium, iron, zinc and phytate x calcium/zinc were 0.22, 4.88, 11.1 and 89.0, respectively, with a large variation between urban and rural areas. The phytate:zinc molar ratios ranged from 6.2 to 14.2, whereas the phytate x calcium/zinc molar ratios were from 63.7 to 107.2. The proportion of subjects with ratios above the critical values of phytate to iron, phytate to calcium, phytate to zinc and phytate x calcium/zinc were 95.4, 43.7, 23.1 and 8.7%, respectively. All the phytate/mineral ratios of rural residents were higher than that of their urban counterparts. CONCLUSIONS: The dietary phytate intake of people in China was higher than those in Western developed countries and lower than those in developing countries. Phytate may impair the bioavailability of iron, calcium and zinc in the diets of people in China.     

Phytate, zinc, and calcium contents of 30 East African foods and their calculated phytate:Zn, Ca:phytate, and [Ca][phytate]/[Zn] molar ratios

Representative samples of 30 staple Malawian foods, raw and prepared “as eaten,” were analyzed for phytate using an anion-exchange method, and for calcium and zinc by flame atomic absorption spectrophotometry. Phytic acid contents expressed on a fresh weight (FW) basis ranged from 211–1089 mg/100 g for cereals and 166–1297 mg/100 g for legumes, to 4–97 mg/100 g for leaves, 10–59 mg/100 g for roots, and 11–25 mg/100 g for fruits. In general, leaves had the highest calcium content (81–514 mg/100 g FW), followed by kidney beans (90 mg/100 g FW), and dry pigeon peas (112 mg/100 g FW). The calcium content of other foods analyzed was relatively low. The zinc content of wild blight, cassava leaves, and okra leaves was comparable to that for the less refined cereals and legumes (i.e., > 1.0 mg/100 g FW), but higher than that of highly refined cereals, pumpkin leaves, chinese cabbage, and other foods analysed (i.e., < 1.0 mg/100 g FW). Cooking had no effect on the phytate content of cereals, but milling and fermentation reduced both the phytate and zinc contents of maize flour. The phytate:Zn molar ratios calculated for all cereals and most legumes analyzed were greater than 20:1. Corresponding Ca:phytate molar ratios were low. Fruits, except for mangoes, vegetables, and roots, had low phytate: Zn molar ratios, but their Ca:phytate and [Ca][phytate]/[Zn] molar ratios were high. Mangoes had high phytate:Zn, Ca:phytate, and [Ca][phytate]/[Zn] molar ratios. These analytical results suggest that the bioavailability of zinc in the Malawian diet is probably low, due to the high phytic acid content of the staple foods.     

Low zinc,iron, and calcium intakes of Northeast Thai school children consuming glutinous rice-based diets are not exacerbated by high phytate

Phytate, a salt of phytic acid (myo-inositol 1,2,3,4,5,6-hexakisphosphate), is found in certain plant-based foods. It strongly chelates minerals, forming insoluble complexes in the small intestine that cannot be digested or absorbed. Information on the phytate content of rice-based diets of children in Northeast Thailand is limited. In this study 1-day weighed duplicate diet composites were collected from 40 Northeast Thai children (age 6–13 years) randomly selected from participants (n=567) of an efficacy trial in Ubon Ratchathani province. Diet composites were analyzed for zinc, iron, and calcium by atomic absorption spectrophotometry, and for phytate (as inositol penta-phosphate and hexa-phosphate) by high-performance liquid chromatography; the accuracy and precision were established using a certified reference material for the minerals and an inter-laboratory comparison for phytate. The median (1st, 3rd quartiles) zinc, iron, and calcium contents of the diet composites were 4.3 (3.7, 6.1), 4.3 (3.2, 6.5) and 130 (82, 216) mg/day, respectively. The inositol penta-phosphate and hexa-phosphate levels were so low they were below the detection limit, attributed in part to leaching of water-soluble potassium and magnesium phytate from glutinous rice after soaking overnight before cooking. Clearly, phytate will not compromise mineral absorption from these diets. Instead, low zinc intakes are probably primarily responsible for the low zinc status of these children. In contrast, although intakes of dietary iron appear low, the prevalence of biochemical iron deficiency was also low, suggesting that iron absorption may have been higher than previously assumed. Whether the low calcium intakes compromise optimal bone health in these growing Northeast Thai school children is unknown.     

Low zinc, iron, and calcium intakes of Northeast Thai school children consuming glutinous rice-based diets are not exacerbated by high phytate

Phytate, a salt of phytic acid (myo-inositol 1,2,3,4,5,6-hexakisphosphate), is found in certain plant-based foods. It strongly chelates minerals, forming insoluble complexes in the small intestine that cannot be digested or absorbed. Information on the phytate content of rice-based diets of children in Northeast Thailand is limited. In this study 1-day weighed duplicate diet composites were collected from 40 Northeast Thai children (age 6-13 years) randomly selected from participants (n=567) of an efficacy trial in Ubon Ratchathani province. Diet composites were analyzed for zinc, iron, and calcium by atomic absorption spectrophotometry, and for phytate (as inositol penta-phosphate and hexa-phosphate) by high-performance liquid chromatography; the accuracy and precision were established using a certified reference material for the minerals and an inter-laboratory comparison for phytate. The median (1st, 3rd quartiles) zinc, iron, and calcium contents of the diet composites were 4.3 (3.7, 6.1), 4.3 (3.2, 6.5) and 130 (82, 216) mg/day, respectively. The inositol penta-phosphate and hexa-phosphate levels were so low they were below the detection limit, attributed in part to leaching of water-soluble potassium and magnesium phytate from glutinous rice after soaking overnight before cooking. Clearly, phytate will not compromise mineral absorption from these diets. Instead, low zinc intakes are probably primarily responsible for the low zinc status of these children. In contrast, although intakes of dietary iron appear low, the prevalence of biochemical iron deficiency was also low, suggesting that iron absorption may have been higher than previously assumed. Whether the low calcium intakes compromise optimal bone health in these growing Northeast Thai school children is unknown.     

Nutritional status and phytate:zinc and phytate x calcium:zinc dietary molar ratios of lacto-ovo vegetarian Trappist monks: 10 years later

A nutrition assessment of 16 members of a community of lacto-ovo vegetarian Trappist monks was conducted in 1977. Plasma zinc was found to be low-normal, which was attributed primarily to high intakes of phytate-containing foods. Individual and group counseling were instituted over a 10-year period in an attempt to emphasize the importance of wise food selection within the constraints of lacto-ovo vegetarianism. In 1987, a more comprehensive nutrition assessment of 21 members of the same community was performed. Food composites were analyzed, and 3-day instead of 24-hour dietary records were kept. Intakes of phytate-containing foods had decreased from 4,569 to 972 mg/day; intake of dietary zinc had increased from 7.4 to 9.7 mg/day; and the phytate:zinc molar ratio had decreased from 67 to 14 for the years 1977 and 1987, respectively. An analyzed phytate:zinc molar ratio of 9.8 and an analyzed phytate x calcium:zinc molar ratio of 0.3 were representative of the 1987 community. Both were within normal ranges. Plasma zinc had risen to upper-normal levels. The 1987 nutrition assessment showed that it is possible to be adequately nourished with a lacto-ovo vegetarian diet provided one has proper knowledge of the phytate-containing foods and the methods for compensating with foods of greater mineral density (primarily zinc).     

Phytate:zinc and phytate X calcium:zinc millimolar ratios in self-selected diets of Americans, Asian Indians, and Nepalese

The literature indicates that phytate:zinc and phytate X calcium:zinc millimolar ratios of a diet may provide useful indexes of the bioavailability of dietary zinc. However, there is little information on the phytate:zinc and phytate X calcium:zinc millimolar ratios for total human diets. We have therefore determined the phytate:zinc and phytate X calcium:zinc millimolar ratios of self-selected diets of 29 American omnivores, 23 American vegetarians, 30 Asian Indian immigrant vegetarians, and 26 Nepalese lactating vegetarians. Criteria for selection of subjects were: good health, no extreme dietary habits, and no intake of nutrient supplements. According to the limited literature, the suggested critical values for phytate:zinc and phytate X calcium:zinc millimolar ratios in animal diets and retrospective calculations from human diets are greater than 10 and greater than 200, respectively. The mean phytate:zinc and phytate X calcium:zinc millimolar ratios of American omnivorous diets in the present study were less than 10 and 200, respectively. Confirmation of the critical molar ratios as indexes of the bioavailability of zinc in human diets has not been established by experimentation. However, if the data from animal studies are applicable to human diets, the present study suggests that phytate has little influence on zinc bioavailability of most American diets. In contrast, the mean phytate:zinc and phytate X calcium:zinc millimolar ratios of all vegetarian diets were above the proposed critical levels. Those data, therefore, suggest that phytate might increase the risk of impaired zinc bioavailability for vegetarians consuming a relatively high level of calcium.     

Determination of phytate, iron, zinc, calcium contents and their molar ratios in commonly consumed raw and prepared food in malaysia

The inhibitory effect of phytate on the bioavailability of iron, zinc and calcium was determined by measuring their molar ratios. A total of 29 food samples consisting of 12 rice and rice products, 5 wheat and wheat products, 5 grains and cereal based products and 7 different popular varieties of cooked rice and rice products were selected. The phytate content was analysed using anion-exchange chromatography whereas mineral contents were analysed using atomic absorption spectrophotometry(AAS). One-way ANOVA test was used to statistically analyse the mean difference between the phytate and mineral contents between the food group samples. In general, results show that cooked products have lower content of phytate and minerals as compared to raw products. This could be due to the influence of the cooking method on phytate and mineral content in the food. Based on one-way ANOVA test, there were no significant difference in phytate and zinc content between four food groups (p >0.05). Significant differences were found only in iron and calcium content (p <0.05). Of the 29 food samples, 25 food samples had a phytate/iron molar ratio > 1, 5 food samples had a phytate/zinc molar ratio > 15 and 23 food samples had a phytate/calcium molar ratio of 0.24. These results show that although many of the food samples analysed had high mineral content, the high phytate content may impair the bioavailability of the mineral in the body.     

Dietary calcium and phosphorus intakes of a sample of Canadian pre-menopausal women consuming self-selected diets

Daily energy protein, calcium and phosphorus intakes of 100 women aged 30.3 ± 6.1 years (mean ± SD) living in a University community and consuming self-selected diets were assessed by calculation from threeday dietary records and food composition data, and by analysis of one-day food composites. The daily calculated intakes were 1803 ± 386 kcal (7544 ± 1615 kj), 74 ± 18 g protein, 943 ± 342 mg calcium and 1398 ± mg phosphorus with a mean Ca:P ratio of 1:1.5 (range = 1.1 to 1.6). Analyzed intakes were 1406 ± 396 kcal (5883 ± 1657 kj), 694 ± 292 mg calcium and 967 ± 335 mg phosphorus with a mean Ca:P ratio of 1:1.3 (range = 1:2.3 to 1:1). Mean calculated calcium, phosphorus and protein intakes exceeded the Canadian Dietary Standard (CDS) recommendation and only 8% of the subjects received calcium intakes less than two-thirds of the CDS recommendation. In contrast, the mean energy intake was below the CDS recommendation for women of comparable ages and activity patterns, 14% of the subjects obtaining less than two-thirds of this level. Six percent of the subjects had high phosphorus intakes (>2000 mg/day) and 8% had Ca:P ratios wider than 1:2. Milk and milk products were the major food sources of both calcium (66.7%) and phosphorus (37.1%), and breads and cereals (25.4%) followed by meat and meat substitutes (20.7%) were important sources of energy. Highly significant correlations (P<0.001) were noted between analyzed intakes of energy, calcium and phosphorus and those calculated from the corresponding record day. Mean calculated intakes and the calcium and phosphorus densities were higher than corresponding mean analyzed intakes (energy: 20.8%, calcium: 28.2%, phosphorus: 37.8%), (P<0.01), but Ca:P ratios were very similar — calculated Ca:P ratio = 1:1.5, analyzed Ca:P ratio = 1:1.3. The calcium content and Ca:P ratios of the majority of these diets appeared to pose no risk to accelerated bone loss in later life.     

Studies on the phytate: zinc molar contents in diets as a determinant of Zn availability to young rats

1. Studies were carried out in vitro to examine the effects of phytate on the solubility of the trace elements zinc, copper and manganese. Appropriate volumes of a solution of sodium phytate were added to a mineral solution to achieve phytate: Zn values of from 0 : 1 to 45 : 1. In a second series the same values for phytate: Zn were achieved by varying the amount of added Zn at a fixed phytate concentration. 2. In both experiments greater than 85% of the Zn was rendered insoluble at pH 6.5 even at the lowest value for phytate: Zn (5 : 1). The effect of phytate on Zn solubility was greater than effects on Cu or Mn. 3. In a dietary study, rats were offered a semi-synthetic egg-albumin-based diet with added phytate. Two series of diets were prepared, the first had a constant Zn content (18.5 mg Zn/kg) and the amount of sodium phytate varied so as to achieve values for phytate: Zn of from 0 : 1 to 40 : 1 (series 1). In the second series, the same values for phytate: Zn were achieved by adding a fixed amount of phytate (7.4 g phytic acid/kg) while the amount of Zn was varied (series 2). 4. Dietary phytate caused significant reductions in growth rates, plasma Zn concentrations and hair Zn concentrations and greying of the coat at values for phytate: Zn of 15 : 1, 10 : 1, 15 : 1 and 15 : 1, respectively. 5. While phytate was apparently slightly more effective in reducing Zn status when phytate: Zn values were achieved at the lower absolute levels of phytate and zn (series 1 diets), the differences at equivalent phytate: Zn values were small. It was concluded that phytate: Zn values can be used as an indicator of Zn availability from phytate-rich diets. 6. Rats offered three diets containing soya-bean-based textured-vegetable-protein (TVP) exhibited low rates of weight gain compared with rats offered an egg-albumen-based diet of similar Zn content (14.5 mg Zn/kg). Additional Zn supplied in drinking-water (25 mg Zn//l) was without effect on rats consuming the egg-albumin diet but significantly improved the weight gain of rats on the TVP diets. 7. It was concluded that phytate naturally present in TVP behaves similarly to phytate added to an otherwise phytate-free diet and that the reduced availability of Zn in TVP diets can be accounted for entirely by their phytate contents.     

Dietary intakes of urban, high body mass index, African American children: family and child dietary attributes predict child intakes

ObjectiveTo identify family and child nutrition and dietary attributes related to children's dietary intakes.DesignAfrican American children (ages 8-11 years, n = 156), body mass index > 85th percentile, from urban, low-income neighborhoods. Baseline, cross-sectional data collected as part of an ongoing diabetes prevention intervention. Dietary intakes were collected by 3-day food diary to assess total energy, percent fat, discretionary fat, added sugar, whole grains, vegetables, fruit, meat, and dairy. Questionnaires on nutrition and dietary attributes administered to children and parents were used to develop 5 diet-related indices: child knowledge, child preferences, child snack habits, child beverage habits, and family food habits.ResultsA higher child nutrition knowledge score was significantly related to a lower starchy vegetable intake. Higher scores on the child snack habits index were significantly related to higher intakes of fruit, total fruits and vegetables, total fruits and nonstarchy vegetables, and to lower intakes of added sugars. A higher score on the family food habits index was significantly related to lower intakes of total energy and discretionary fat.Conclusions and ImplicationsTargeting both child and family food and nutrition attributes may be used to promote more healthful eating among urban, low-income, overweight African American children.     

Dietary calcium intakes of urban children at risk of lead poisoning.

Dietary calcium is well known to decrease gastrointestinal lead absorption and thereby reduce the risk for lead poisoning. Because children in economically deprived urban centers are especially likely to have excessive lead exposure, we surveyed dietary calcium intakes of 314 children from the greater Newark, New Jersey, area. The areas of Newark and adjacent communities studied had been previously identified as containing significant sources of environmental lead by geographic information systems technology. An abbreviated National Cancer Institute Health Habits and History Questionnaire, modified to focus on foods high in calcium, was used to determine dietary calcium. Calcium intakes were then compared to the new Dietary Reference Intake (DRI) guidelines. The respondents were primarily the parents of African-American and Hispanic children ranging in age from 1 to 8 years, with a mean age of 3.5 years. The most recent blood lead concentration was 11.4 +/- 0.8 microg/dL (mean +/- standard error), and 48.6% had concentrations at or above the current guideline of 10 microg/dL. Quintiles of calcium intake were: 221 +/- 13; 488 +/- 9; 720 +/- 6; 885 +/- 6; and 1,389 +/- 49 mg/day. Fifty-five of 175 (31.4%) children aged 1-3 years had calcium intakes below the DRI, as did 82 of 139 (59.0%) children aged 4-8 years. The percentage of mothers reporting lactose intolerance in their children was 2.5%. The observation that the children in the highest quintile easily exceeded the DRIs for calcium suggests that urban parents who include dairy foods in their childrens' meals can provide a diet that meets the DRI guidelines. Children in the lowest quintiles are at risk of increased absorption of the environmental lead to which they are inevitably exposed, as well as other problems associated with a low intake of dietary calcium. The data suggest that both lead exposure and low dietary calcium continue to pose significant health risks to urban minority children.     

Dietary intakes and activity levels of stunted and non-stunted children in Kingston, Jamaica. Part 1. Dietary intakes

The dietary intakes of stunted and non-stunted children were measured on enrollment to a longitudinal study of growth and development. Children aged 9-24 months were recruited by house to house survey of several poor areas of Kingston. All children with height for age less than -2 SD of the NCHS standards and weight for height below the standard median were enrolled. Alternate stunted children were matched for age and sex with the non-stunted child (height for age greater than -1 SD) living nearest. Dietary information was obtained by two 24-h recalls. Mean trainer-interviewer reliability was greater than 90 per cent throughout the study. Correlation between energy intakes on the 2 days was 0.68 (P less than 0.001). Stunted children had a significantly less varied diet, fewer dairy products and fruit than non-stunted children. Protein intakes met requirements. Energy intakes were similar in both groups and approximately 200 kcal below the recommended intake. Energy and protein intakes per kg were significantly higher in the stunted children than in non-stunted children (energy P less than 0.001, protein P less than 0.005). Greater morbidity in the stunted children could account for some, but not all, of this difference. Children with lower weight for height had lower intakes (energy P less than 0.05, protein P less than 0.01). Intakes were greater in children who lived in better housing, with more household possessions and whose mothers had more skilled occupations. Good reliability and the above associations indicate that the data are valid.     

The concentrations of iron,calcium, zinc and phytate in cereals and legumes habitually consumed by infants living in East Lombok,Indonesia

There is a paucity of analysed data on contents of minerals and phytate in Asian complementary foods. Thus, cereals and legumes (n=27) consumed by Indonesian infants were analysed for iron, zinc and calcium using flame Atomic Absorption Spectrophotometry and for phytate using high performance liquid chromatography (HPLC). Results (per 100 g dry weight) showed unfortified cereals had lower concentrations of zinc (1.5–3.2 mg/100 g vs. 3.2–5.8 mg/100 g), iron (0.3–5.4 mg/100 g vs. 2.9–17.4 mg/100 g), calcium (5–48 mg/100 g vs. 41–926 mg/100 g) and phytate (hexa- and penta-inositol phosphates; 70–246 mg/100 g vs. 177–1042 mg/100 g) than legumes and lower phytate: mineral molar ratios. Tempe had the lowest concentration of phytate (236–366 mg/100 g vs. 763–1042 mg/100 g), and the lowest molar ratios of phytate: zinc (6.3–12.6 vs. 14.3–21.1) and phytate: iron (1.6–4.0 vs. 5.0–11.3) compared to other soybean products. Milling increased concentrations of iron and calcium in rice (1.2 vs. 0.4 mg/100 g, p=0.002; and 8.1 vs. 5.1 mg/100 g, p=0.029, respectively); but reduced zinc (1.6 vs. 1.7 mg/100 g, p=0.013). Boiling increased calcium concentrations in rice and rice flour (5.1–16.7 mg/100 g, p=0.004; and 8.1–31.4 mg/100 g, p<0.001, respectively); whereas frying decreased iron concentrations in tempe (13.3–6.1 mg/100 g, p=0.038). When expressed per infant portions, fortified cereals and tempe were the best sources of zinc, iron, and calcium, because of their relatively high mineral and low phytate contents.     

[Phytate][calcium]/[zinc] ratios in Asian immigrant lacto-ovo vegetarian diets and their relationship to zinc nutriture

Lacto-ovo vegetarians often have low zinc intakes coupled with concomitant high intakes of dietary fiber, phytate and calcium. The latter two dietary components appear to exert a synergistic inhibitory effect on zinc absorption. In this study 30 1-day diet composites were prepared for analysis from 3-day weighed diet records completed by 112 Asian immigrants consuming predominantly lacto-ovo vegetarian diets and compared with 30 omniverous diet composites. Analysed mean (±S.D.) daily intakes were: energy (kcal) 1892±445, calcium (mg) 1093±467, zinc (mg) 8.5±4.5, phytate (mg) 1487±791, neutral detergent fiber (g) 26.8±13.2. Median phytate: Zn molar ratio for Punjabi diets was 17.7 (range=5-50) and median [phytate][Ca]/[Zn] molar ratio was 475.4 (range=48-1150) compared with median values of 8.3 and 130.9 respectively for omniverous diets. Thirty-seven percent of the Punjabi diets had phytate:Zn ratios>20 and 80% had [phytate][Ca]/[Zn] ratios>200, levels shown to jeopardize zinc status in man. Thirty-two percent of the Punjabi subjects had low serum zinc levels (ie<70 g/dl) which may be associated with the unusually high dietary [phytate][Ca]/[Zn] ratios. The latter are attributed to high intakes of unleavened wholemeal chapatti bread, dairy products, and low intakes of flesh foods.     

Effects of dietary phytate, calcium and magnesium levels on zinc bioavailability to rats

Young rats were fed diets containing 12 mg Zn/kg and varied levels of sodium phytate for 21-day ad libitum feeding periods. In experiment 1, Ca levels were 0.3, 0.5, 0.8 and 1.0%, and phytate:Zn molar ratio varied between 0 and 50. In experiment 2, Ca was maintained at 0.3%, Mg levels were 0.07, 0.22 and 0.37%, and phytate:Zn molar ratios were 0, 10, 20 and 30 at each Mg level. Major response criteria were body weight gain and tibia Zn accumulation. Weight gain was not influenced by Ca level in the absence of phytate or by phytate at 0.3% Ca; it was increasingly depressed as phytate was increased and by each increase in Ca in the presence of phytate. Total tibia Zn content was decreased at the highest Ca level in the absence of phytate; increasing the phytate progressively depressed tibia Zn at all Ca levels. Mg and phytate additions did not affect weight gain. Tibia Zn tended to be depressed by Mg and by phytate but these effects were significant only at the highest levels of the combined additions. These data corroborate and extend previously published findings on Ca and phytate effects on Zn utilization and show bone Zn accumulation to be a more sensitive criterion than weight gain in this connection. They also indicate that Mg exerts a less pronounced effect on Zn utilization in phytate-containing diets than does Ca.     

Dietary iron, zinc, and calcium and the risk of lung cancer

BACKGROUND: Iron, zinc, and calcium are all involved in the metabolism of reactive oxygen species and may compete with each other for similar binding sites. Dietary intakes of these micronutrients have been associated with altered risks of colorectal, breast, and prostate cancers. METHODS: In this Massachusetts hospital-based case-control study of 923 patients with lung cancer and 1125 healthy controls, we studied the associations between dietary iron, zinc, and calcium intake and the risk of lung cancer. Dietary intake was assessed at the time of recruitment (1992 to 2000) with the use of a 126-item semiquantitative food-frequency questionnaire. We analyzed the data using multiple logistic regression models adjusting for smoking history and other potential risk factors. RESULTS: The adjusted odds ratios of dietary iron, zinc, and calcium from food sources were 1.45 (95% confidence interval=1.03-2.06), 0.71 (0.50-0.99), and 1.64 (1.17-2.29), respectively, for the highest quintile versus the lowest quintile of each micronutrient. Stronger associations between micronutrients and lung cancer risk were found when iron, zinc, and calcium were included together in the same model. The associations between dietary micronutrients intake and lung cancer risk were stronger among current smokers than among former smokers. When we examined intake from supplements as well as diet, associations were similar to those for diet alone. CONCLUSIONS: Dietary iron, zinc, and calcium may play an important role in the development of lung cancer, especially among current smokers. These results need to be confirmed in large prospective studies.     

Dietary fiber content of a simulated American diet and selected research diets

Few studies accurately report total-dietary-fiber (TDF) content of current and alternative diets. In this study we analyzed and calculated TDF content of a simulated American diet with household Nationwide Food Consumption Survey data. We also analyzed the fiber content of four research diets: control; bean; high fiber, maintenance (HFM); and high carbohydrate, high fiber (HCF). Analyzed and calculated fiber values for the simulated diet were similar. The simulated, control, bean, HFM, and HCF diets provided 5.6, 8.1, 12.2, 17.4, and 22.8 g TDF/1000 kcal, respectively. Soluble-fiber content ranged from 1.7 g/1000 kcal for the simulated diet to 6.1 g/1000 kcal for the HCF diet. Cereal products contributed the most to total fiber content of the simulated diet, followed in order by vegetables, legumes, fruits, and miscellaneous foods. Fiber content of the simulated diet was below recommended levels. The HFM diet is suggested for individuals desiring to increase their dietary fiber intake.     

Dietary quality and adequacy of micronutrient intakes in children

Presented are longitudinal studies, extending from infancy (n 180) to 2 years of age (n 130) and 6 years of age (>70% participation) of diet and Fe status in a population with high birth weight, high frequency of breast-feeding and, at the time of the study, high intake of cow's milk during the weaning period. The association between socio-demographic and dietary factors was also studied, together with Fe status in early childhood and developmental status at 6 years. Fe status was found to be poorer than in the neighbouring Nordic countries. Every fifth 1-year-old was Fe-deficient (serum ferritin <12 microg/l and mean corpuscular volume <74 fl). It was demonstrated by regression analysis that Fe status was negatively associated with cow's milk consumption at 9-12 months (significant at >460 g/d) and was weakly positively associated with fish, meat and Fe-fortified cereal consumption. Fe-deficient infants had a shorter duration of breast-feeding, and breast-feeding was related to slower growth, which can protect from worsening Fe status. Fe deficiency was less common at ages 2 and 6 years. Maternal factors associated with lower adherence to the recommended infant diet were less education, lower age and smoking. In a multiple stepwise regression analysis that included food factors, socio-demographic factors were not found to be associated with Fe status. Fe-depleted and Fe-deficient 1-year-olds had lower fine motor scores when they were 6 years old than those who were not Fe-deficient or Fe-depleted. The findings of these studies have already led to changes in the local recommendations for diet in infancy. The results suggest that Fe deficiency at 12 months of age affects development at 6 years of age. The studies indicated that mothers with less education, who smoked and who were younger needed more guidance concerning recommendations about diet in infancy.