Relationship between dietary and biochemical measures of nutritional status in HANES I data

Exploring ethnic differences in the distribution of blood test results in healthy adult populations to inform earlier cancer detection: a systematic review

BACKGROUND

In primary care, health professionals use blood tests to investigate nonspecific presentations to inform referral decisions. Reference ranges for the commonly used blood tests in western countries were developed in predominately White populations, and so may perform differently when applied to non-White populations. Knowledge of ethnic variation in blood test results in healthy/general populations could help address ethnic inequalities in cancer referral for diagnosis and outcomes.

OBJECTIVE

This systematic review explored evidence of ethnic differences in the distribution of selected blood test results among healthy/general populations to inform future research aimed at addressing inequalities in cancer diagnosis.

METHODS

We searched PubMed and EMBASE to identify studies reporting measures of haemoglobin, MCV, calcium, albumin, platelet count, and CRP in nondiseased adults from at least 2 different ethnic groups. Two reviewers independently screened studies, completed data extraction and quality assessment using an adapted Newcastle-Ottawa scale. Participants were stratified into White, Black, Asian, Mixed, and Other groups. Data were synthesised narratively and meta-analyses were conducted where possible.

RESULTS

A total of 47 papers were included. Black men and women have lower average values of haemoglobin, MCV, and albumin, and higher average values of CRP relative to their White counterparts. Additionally, Black men have lower average haemoglobin than Asian men, whereas Asian women have lower average CRP values when compared with White women.

CONCLUSIONS

There is evidence of ethnic differences in average values of haemoglobin, MCV, CRP, and albumin in healthy/general populations. Further research is needed to explore the reasons for these differences. Systematic review registration: CRD42021274580.

A thermolyzed diet increases oxidative stress, plasma α-aldehydes and colonic inflammation in the rat

A thermolyzed diet has the potential of providing exogenous oxidative stress in the form of advanced glycation end-products (AGE) and decreased thiamin. There is then a possibility that it could result in intracellular exposure to alpha-oxoaldehydes (glyoxal and methylglyoxal (MG)) with metabolic and genetic consequences. Two groups of Fischer 344 rats were fed the following diets: group A was given an AIN93G diet (control diet), while group B was given a thermolyzed AIN93G diet for 77 days. At the end of 77 days TK activity in red blood cells; glyoxal/MG levels in the plasma; glyoxal/MG HI protein adducts and dicarbonyls in the plasma, liver and colon tissues; glutathione levels of whole blood; and oxidative stress/inflammatory markers in the colon were measured. The thermolyzed diet resulted in: decreased thiamin status, increased plasma levels of glyoxal/MG and their adducts, increased protein dicarbonyls in the liver and plasma, lowered blood glutathione levels, increased infiltration of macrophages and increased colon nitrotyrosine levels. The thermolyzed diet increased the body burden of AGEs and decreased the thiamin status of the rats. This increased endogenous alpha-oxoaldehydes and oxidative stress has the potential to injure tissues that have low levels of antioxidant defenses such as the colon.

Blood thiamin status and determinants in the population of Seychelles (Indian Ocean)

STUDY OBJECTIVE

Micronutrient deficiencies have become rare in industrialised countries as availability of fresh food, supplementation, and fortification have improved but a less favourable situation may still prevail in many developing countries. Blood thiamin status and determinants were therefore investigated in the Seychelles in view of the high incidence of dilated cardiomyopathy and as the staple diet is polished rice that is deficient in thiamin.

DESIGN

This was a cross sectional population study using an age and sex stratified random sample.

SETTING

Seychelles Islands (Indian Ocean).

PARTICIPANTS

A subsample of 206 subjects aged 25-64 years from the population of Seychelles.

MAIN OUTCOME MEASURES

Measurement of total thiamin concentration in whole blood using high performance liquid chromatography. Dietary variables measured using a face to face semi-quantitative food questionnaire.

RESULTS

Mean (SD) whole blood thiamin concentration was 77.9 (22.4) nmol/l and low concentration (< 70 nmol/l) was found in 37% of the subjects (95% CI: 31%, 44%). Blood thiamin was significantly related to education and diet but not to age, sex, smoking, and body mass index. Blood thiamin was associated positively with meat, vegetable, salad, and tea intake and negatively with alcohol and fish intake. However, no combination of the examined variables could explain more than 15% of the observed variance in blood thiamin values.

CONCLUSIONS

These data suggest that the distribution of blood thiamin in the sampled population is shifted to lower values compared with that generally accepted as normal in European populations. Further research should establish the significance of such lower values in this specific population to facilitate clinical and public health action as necessary.

Long-term effect of low-dose combined steroid contraceptives on body iron status

The present study was aimed to evaluate iron metabolism in active and healthy adult women having taken oral contraceptives (OC) long-term. Mean dietary iron intake in age-matched control and experimental groups was adequate. Serum ferritin used as a marker for body iron stores was marginal in both groups underlying a high prevalence of deficient-iron reserves among subjects. This parameter was not correlated to the iron content of the diet. The serum iron concentration was significantly higher in OC users than control subjects (p less than 0.001). Biochemical results commanded a discussion on the pertinence of evaluating the total dietary iron intake and on the sensitivity of biochemical methods used to assess the iron status.

Influence of aging on vitamin A transport into the lymphatic circulation

Vitamin A is a lipid soluble essential dietary micronutrient. Because aging individuals have elevated serum levels of vitamin A, we tested the intestinal absorptive capacity of the vitamin in aging rats by measuring the appearance rate of vitamin A in the lymphatic circulation as a measure of intestinal absorption. We infused the vitamin in a physiological concentration of 350 nM into the proximal jejunum of groups of Sprague-Dawley rats 2 to 23 months of age. Lymph was collected for 6 h and vitamin A radioactivity was measured. Lymph flow rate over 24 h ranged from 16 +/- 3.1 ml in the oldest to 21.5 +/- 2.4 ml in the youngest animals. Vitamin A transport into lymph was highest at 23 months of age, reaching 7869 +/- 154 pmol/6 h as compared to 6732 +/- 106 pmol/h at 2 months (p less than .01). The increase in vitamin A absorption with aging represented an increase from 35.6% of the infused vitamin at 2 months to 41.6% at 23 months of age. Because of the cumulative storage of vitamin A in the liver this increase in absorption and lymphatic appearance is of nutritional and metabolic significance. Increased lymphatic appearance of the vitamin could explain its higher absorption and serum levels in aging individuals.

Diet, nutritional status, and cancer risk in American blacks

About 35% (10-70%) of all cancers may be associated with nutritional causes (1). However, while natural or added substances in foods may be carcinogenic, nutritional deficiencies or excesses may promote carcinogenesis. We compared data from blacks and whites using dietary and nutritional status surveys in the United States to determine whether the poorer dietary patterns and nutritional status of American blacks may be associated with their higher incidence and mortality from certain cancers (compared with whites). Our review indicates that blacks eat more nitrate and animal foods and not enough fiber in relation to protein, fat, and carbohydrate. Blacks also have poorer nutritional status with respect to getting enough thiamine, riboflavin, vitamins A and C, and iron, to being obese (females), and to being underweight (males). This is in agreement with hypotheses regarding the interactions between diet and cancer (associations found in whites) and dose-response relationships reported for some cancers for which blacks have a higher incidence and mortality than whites. More large-scale prospective case-control and cohort studies are needed in both blacks and whites to elucidate the contribution of specific dietary and nutritional factors to the risk of specific cancers in these population groups. However, such studies must be preceded by methodological research to obtain more valid measures of dietary and nutritional status.

A study of inter- and intrasubject variability in seven-day weighed dietary intakes with particular emphasis on trace elements

In this study of inter- and intrasubject variance of trace element (TE) dietary intake data, 14 female university students recorded weighed, self-selected food intakes for seven consecutive days, starting on a randomly selected day of the week. Daily intakes of energy, dietary fiber, macronutrients, 7 vitamins, and Fe, Zn, Cu, Mn, and Se were calculated using food composition tables and literature values. Analysis of variance showed a significant weekend effect for energy and TE intakes that was reduced when data were expressed on the basis of nutrient densities. No day of the working week or training effect was noted for energy or any nutrient. The ratios of the inter- to intrasubject coefficient of variation for all the nutrients were surprisingly constant. However, the overall coefficients of variation-Fe, 36.5%; Zn, 45.7%; Cu, 43.7%; Mn, 58.2%, and Se, 52.7%-were markedly lower than for vitamin A (109.0%), Vitamin D (117.1%), and linoleic acid (82.2%), but slightly higher than those for energy (27.2%) and carbohydrate (30.1%). The widespread distribution of TE in the diets results in comparable reliability for dietary studies of TE and macronutrients. The 95% confidence intervals for mean individual TE intakes ranged from 25% (Zn) to 40% (Se). These relatively large uncertainties make it essential that any assessment of the significance of correlations between dietary TE intakes and biochemical indices takes into account the intra-individual variation associated with both variables.

Assessment of nutritional status: functional indicators of pediatric nutriture

The author speaks to the need to update our conceptual approach and our technical capacities for nutritional status assessment and to devise innovative ways to apply them to pediatric practice. The article discusses and evaluates conventional, static indices of nutriture and the importance of history and the physical examination. Focus is then placed on the concept of the functional assessment of nutritional status and its potential for clinical use.