Search PubMed⌕ Search

Biomedical subjects

W Mertz

Publications and source records attributed to W Mertz.

At least 55 records · Page 3Linked to original sources
PubMed1980

Mineral elements: new perspectives.

Research during the 1970s brought out the importance of interrelationships among trace elements and better definition of human mineral requirements. These have practical implications which are pointed up in this paper. For example, iron absorption (important in meeting requirements of women of child-bearing age) can be improved by co-ingestion of ascorbic acid and/or meat, poultry, or fish products. The interplay between calcium and protein metabolism is also summarized. To accommodate as yet incomplete knowledge, the 1980 revision of the Recommended Dietary Allowances has incorporated the concept of "ranges of safe and adequate intakes" for two minerals and six trace elements. Copper and chromium appear to be of special importance, and their adequacy in the diet cannot be taken for granted. The nutrient density of these two elements per 1,000 kcal can be used in assessing intake in broad terms of "poor," "marginal," or "adequate," although this is by no means a quantitative type of judgment.

Adult↗
PubMed1979

Zinc and copper in self-selected diets.

Levels of zinc and copper in the self-selected diets of twenty-two men and women were determined by atomic absorption spectrophotometry. Sixty-eight per cent of the subjects consumed less than two-thirds of the recommended allowance for zinc (15 mg). Eighty-one per cent consumed less than two-thirds of the suggested level of copper (2.0 mg). Average daily intake of protein exceeded the recommended allowance. However, the mean zinc:calorie ratio for those subjects was only 4.19 mg. per 1,000 kcal. Using the recommended allowances for zinc and for energy, the zinc:calorie ratio would be 6.5 mg. per 1,000 kcal. For copper, the suggested nutrient density is 0.85 mg. per 1,000 kcal vs. the 0.50 mg. per 1,000 kcal observed in this study. These metallo:calorie ratios indicate that the nutrient density of these two trace elements in the diet is low and that diets supplying adequate amounts of energy and protein do not guarantee adequate levels of zinc and copper.

Adolescent↗
PubMed1978

Estimation of available dietary iron.

Dietary iron requirements are dependent on the amount and availability of food iron ingested. On the basis of recent studies of food iron absorption employing extrinsic tag techniques, the availability of heme iron has been defined and estimates of the availability of nonheme iron based on the amounts of enhancing substances appear possible. A model has been developed whereby the availability of iron in a given meal may be estimated. Calculations are made on a meal basis of 1) the amount of heme iron and its availability, and 2) the amount of nonheme iron and its availability as influenced by the meal's content of enhancing factors. Examples of these calculations are provided.

Absorption↗
PubMed1977

A biphasic response of rats to cobalt.

The study was designed to confirm a previous, unexpected observation of a strong growth depressing effect of 1 microgram cobalt/g in rats fed lactalbumin based diets. The addition of 0.25, 0.5, and 1.0 microgram of cobalt/g to the basal diet containing 0.056 microgram/g depressed growth rates of rats progressively with increasing doses. This depression was overcome by increasing the cobalt supplement to 2 microgram/g, and additional weight gain was observed with 3 microgram/g. Higher concentrations were progressively toxic. Hemoglobin concentrations, hematocrits, and thyroid retention of intravenously injected sodium iodide all were lowest in rats fed the diet containing 1 microgram cobalt/g and increased with lower and higher concentrations of cobalt. The opposite was true for fasting serum glucose levels, which were elevated in rats fed the 1 microgram/g diet and low in rats fed the 3 microgram/g diet or control diet. This biphasic response to cobalt is consistent with the hypothesis that cobalt in low concentrations may have an essential function in the rat. However, an alternative explanation, an interaction of cobalt with a toxic constituent of the diet, has not yet been ruled out.

Animals↗
PubMed1977

Urinary chromium excretion and atherosclerotic manifestations in two Finnish male populations.

The urinary exretion of chromium was studied for relationships to atherosclerotic diseases in two rural Finnish male populations, aged 55 to 74; one from eastern Finland, the other from the southwestern part of the country. A 10-year follow-up had shown a particularly high mortality from coronary heart disease in the eastern area where the concentrations of chromium in the drinking water were lower than in the western area. The 24-hr urinary excretions of chromium of the two populations were markedly low (east, mean +/- SEM, 3.60 +/- 0.15 microgram; west, 3.74 +/- 0.13 microgram), suggesting a suboptimal chromium intake in both populations. No consistent differences were found in urinary chromium excretions between groups with atherosclerotic diseases and reference groups. The role of low chromium intake in the pathogenesis of atherosclerosis deserves further study.

Aged↗
PubMed1973

Chromium in refined and unrefined sugars--possible nutritional implications in the etiology of cardiovascular diseases.

It has recently been discovered that chromium is an essential element, particularly in relation to carbohydrate metabolism. Food refinement leads to a loss of chromium as well as of other trace elements. The nutritional significance, particularly in relation to cardiovascular diseases, of the excessive consumption of refined food, poor in trace elements, is not well understood. The first results of a WHO study on the chromium content of different brands of refined and unrefined sugars obtained from various countries are described here. Flameless atomic absorption was used for chromium analysis. Molasses have the highest chromium content (0.266 mg/kg), followed by unrefined (0.162) and brown (0.064) sugars. Refined sugar has the lowest chromium content (0.020 mg/kg). No differences associated with the geographic origin of the sugars were observed.

Carbohydrates↗