Biomedical subjects

J R Turnlund

Publications and source records attributed to J R Turnlund.

48 records · Page 3Linked to original sources

PubMed1985

Zinc utilization in young men fed adequate and low zinc intakes.

Zinc absorption and balances were measured in six young men who were confined while participating in a 75-d metabolic study. A diet of conventional food providing either 16.5 or 5.5 mg Zn/d was fed. Apparent absorption of zinc was calculated from the zinc balance data and from the absorption of a zinc stable isotope added to the diet. The apparent zinc absorption calculated from the isotope data was about 25% when 16.5 mg zinc was fed; it increased to about 53 and 49% after 13 and 42 d, respectively, when 5.5 mg zinc was fed. Total zinc absorption fell from 4.1 mg/d to 2.7-2.9 mg/d during the low zinc period, however. This zinc absorption was sufficient to maintain crude zinc balances in five of the six subjects. Neither serum nor urinary zinc levels changed significantly during the period of feeding low levels of zinc. It appears that zinc absorption readily responds to changes in dietary zinc and that an intake of 5.5 mg Zn/d for about 8 wk does not cause serum or urinary zinc level to fall.

Absorption↗

PubMed1985

Zinc and copper in Asian pregnancies--is there evidence for a nutritional deficiency?

In 92 Hindu Asians, 59% of them vegetarian, and 51 Europeans longitudinal measurements were made during pregnancy of the zinc and copper concentrations in plasma and hair together with urinary zinc excretion, as indices of their zinc and copper status. Maternal diets were assessed once at booking. Zinc intakes ranged from 3.1 to 16.9 mg/day, with average intakes least in vegetarian Hindus and most in Europeans. Average copper intakes ranged between 1.48 and 1.80 mg/day and were similar in the three patient groups. Both ethnic groups showed the pregnancy-associated fall in the plasma concentration of zinc and rise in that of copper but throughout the study Hindus had statistically significant lower levels of zinc and higher levels of copper than Europeans. Urinary zinc excretion was not only significantly lower throughout the study in Hindus than in Europeans but the increase in excretion which occurred after 20 weeks gestation was smaller. There were no ethnic differences in the zinc content of hair. Urinary zinc excretion correlated with both plasma zinc levels and dietary zinc. Mean birthweight in the Hindus was 2912 g and 34% of infants were below the 10th centile, using the Aberdeen standards, compared with 6% of the European babies (mean birthweight 3349 g). No association was found between crude or adjusted birthweight and any of the measures of zinc or copper status in either ethnic group. The Hindus had an apparently lower average zinc status than the Europeans, but there was no evidence that this had acted as a nutritional constraint and was the cause of their slower rate of intrauterine growth.

Adult↗

PubMed1984

A stable isotope study of zinc absorption in young men: effects of phytate and alpha-cellulose.

A 63-day study was conducted with young men confined to a metabolic unit to study the effects of a alpha-cellulose and phytate on zinc absorption. A liquid formula diet was used throughout the experiment. During each of three dietary treatments, (basal diet, basal diet + alpha-cellulose, or basal diet + phytate), 67Zn, a stable isotope of zinc, was added to the diets to measure zinc absorption. Zinc absorption was determined by fecal monitoring of 67Zn, measured by thermal ionization mass spectrometry. Analytical precision of all measurements was within 1%. Average zinc absorption was 34.0 +/- 6.2% from the basal diet and 33.8 +/- 2.9% from the diet with 0.5 g alpha-cellulose per kg body weight added. Zinc absorption fell to 17.5 +/- 2.5% when 2.34 g of phytate as sodium phytate were added to the basal diet. The phytate/zinc molar ratio of the diet was 15. The decrease in zinc absorption was accompanied by increased fecal zinc and decreased urinary zinc. The results suggest that phytate inhibits zinc absorption and high levels of dietary phytate could result in zinc deficiency in man.

Absorption↗

PubMed1983

Use of enriched stable isotopes to determine bioavailability of trace elements in humans.

Use of stable isotopes with analysis by thermal ionization mass spectrometry can determine trace element availability from dietary sources safely and with a high degree of accuracy. Stable isotopes of zinc (70Zn), copper (65Cu) and iron (58Fe) were fed with semipurified diets to humans. Excretion of isotopes was determined by isotope dilution in fecal composites collected for 15 days following the feedings. A thermal ionization, magnetic sector mass spectrometer was used to measure isotopic ratios. Total mineral content of fecal composites was determined by atomic absorption spectrophotometry. Mean absorption of zinc, iron and copper in six elderly men was 17.3, 8.7 and 26.0% respectively. Results agreed closely with absorption determined simultaneously in the same subjects using radioisotopes.

Aged↗

PubMed1983

Copper absorption and retention in pregnant women fed diets based on animal and plant proteins.

Copper absorption was determined by using 65Cu, a stable isotope of copper, in pregnant and nonpregnant women who were confined to a metabolic unit for 21 or 42 days. Absorption and retention of copper were determined from two diets. One diet was comprised primarily of animal protein sources and the other of plant protein sources. The percentage of absorbed copper from the animal protein diet was higher than from the plant protein diet. Copper absorption from the animal protein diet averaged 41.2 and 42.2% in nonpregnant and pregnant women, respectively. Copper absorption from the plant protein diet averaged 33.8% in nonpregnant women and 40.7% in pregnant women. The plant protein diet contained more copper and therefore the absolute amount absorbed was greater from the plant protein diet. The results suggest that either the level of dietary copper or a component of the diet may have an effect on copper absorption. Copper absorption from both diets tended to be higher in pregnant than in nonpregnant women, but the difference was significant only with the plant protein diet. The levels of copper fed in this study, 1.44 and 2.53 mg per day from the animal and plant protein diets, respectively, were sufficient to result in positive balance in all subjects. The amount of copper retained by pregnant women appeared adequate to provide for the increased requirements of pregnancy.

Absorption↗

PubMed1983

Effect of dietary zinc sources and pregnancy on zinc utilization in adult women fed controlled diets.

Five nonpregnant and 10 pregnant women participated in 21-day confined metabolic studies. Two diets each providing 16 mg of zinc per day were fed. In one diet 70% of the total zinc was provided by animal products and 30% was contributed by plant sources. In the second diet the proportions were reversed. Apparent absorption of zinc was determined using the balance technique. During the last 15 days of the study, zinc intake was only slightly greater than the amount of zinc excreted in feces. Mean apparent absorption values did not exceed 5% and did not vary due to diet or pregnancy. Zinc bioavailability was also assessed by measuring the apparent absorption of a stable isotope of zinc (70Zn) added to the diet. There was no significant effect of either diet or pregnancy on 70Zn absorption, which averaged about 25%. Serum zinc values were normal throughout the study and did not change significantly as a function of diet. The pregnant women, however, maintained values that were 19-27% lower than those of the nonpregnant women. In summary, the substitution of animal sources of zinc by plant products did not reduce zinc bioavailability or alter zinc utilization.

Adult↗

PubMed1983

Hospital dietetics and food service in developing countries: I. The Middle East.

A survey of hospital food service and dietetics was conducted in the largest hospitals of six Middle Eastern countries: Bahrain, Jordan, Kuwait, Lebanon, Saudi Arabia, and Syria. There were very few individuals with training in food service and dietetics in any of the countries. The effect of this lack of training on hospital food service and dietetics is discussed. Recommendations are made that would result in improvements in hospital food service and dietetics in the Middle East.

Developing Countries↗

PubMed1983

Hospital dietetics and food service in developing countries: II. Lebanon.

A survey of 15 hospitals in Lebanon revealed that food service personnel in most hospitals had no training in nutrition, dietetics, or food service management. Kitchen sanitation was inadequate. Therapeutic diets were usually incorrectly planned and seldom used. The need for training food service personnel was recognized only in hospitals with some trained persons on the staff.

Data Collection↗

PubMed1983

Hospital dietetics and food service in developing countries: III. Bangladesh.

A survey of 11 hospitals in Bangladesh revealed that most heads of hospital food service had little or no training in nutrition and dietetics, hospital diets were usually inadequate, therapeutic diets were seldom used, and kitchen sanitation was poor. However, in three hospitals in which the heads of food service had some education in nutrition, conditions were markedly better. Even though the results of this survey suggest that major improvements are needed in hospital food service and dietetics in Bangladesh, extensive training programs are probably unrealistic because of the limited economic base of the country. Short-term inservice training programs could result in marked improvement in the quality of food service, sanitation, and the use of therapeutic diets.

Bangladesh↗

PubMed1982

Use of enriched stable isotopes to determine zinc and iron absorption in elderly men.

The absorption of zinc and iron was determined in seven elderly men using the enriched stable isotopes 70Zn and 58Fe. Analyses of isotopic ratios were done using thermal ionization magnetic sector mass spectrometry on chloride solutions of zinc and of iron after separation of zinc from fecal samples by ion exchange and of iron by solvent extraction. Mean apparent zinc absorption in the seven subjects was 17.3 +/- 3.1% (mean +/- SEM) and mean iron absorption was 7.9 +/- 2.5% (mean +/- SEM) when fed a semipurified diet containing 15 mg of zinc and 10 mg of iron daily. Quantities absorbed were equivalent to an average of 2.6 mg of zinc and 0.8 mg of iron per day. These average zinc and iron values are close to previous estimates of endogenous losses of zinc and iron.

Absorption↗

PubMed1982

Copper absorption in elderly men determined by using stable 65Cu.

The apparent absorption of copper was determined in seven elderly men using the stable isotope 65Cu. Analysis of isotopic ratios of copper was done using thermal ionization, magnetic sector mass spectrometry after separation of copper from fecal samples by ion exchange chromatography. Mean apparent copper absorption during the first metabolic period in five men was 23.9 +/- 1.4% (mean +/- SEM) when fed a semipurified diet containing 3.3 mg of copper daily and 9 to 19 g nitrogen from egg albumin. Mean apparent copper absorption in five men during the second metabolic period was slightly but significantly higher, 27.7 +/- 0.31% (mean +/- SEM) when their diet contained 3.3 mg of copper per day and 4.0 to 5.7 g of nitrogen from egg albumin. The quantity of copper absorbed was equivalent to 0.8 mg per day in the first metabolic period and 0.9 mg during second metabolic period and was sufficient to maintain copper balance in these elderly men.

Aged↗

PubMedDate not supplied

Copper absorption in young men fed adequate and low zinc diets.

Copper absorption was measured at two levels of dietary zinc in six healthy young men who were confined to a metabolic unit for a 75 d study of zinc utilization. A diet of conventional foods was fed, providing either 16.5 or 5.5 mg zinc and 1.3 mg copper daily. Copper absorption was determined by feeding 65Cu, a stable isotope of copper, once during the 16.5 mg Zn diet and near the beginning and end of the 5.5 mg Zn diet. Apparent copper absorption averaged 48.1% when the 16.5 mg Zn diet was fed. This was significantly higher than the averages of 37.2 and 38.5% when the 5.5 mg Zn diet was fed. Absorption also differed significantly among subjects. Fecal copper did not differ between diets or among subjects. All subjects were in positive copper balance at both levels of dietary zinc. These results suggest that a dietary zinc intake slightly above the Recommended Dietary Allowance of 15 mg/d does not increase fecal copper loss and does not interfere with copper absorption.

Absorption↗