The double burden of obesity and iron deficiency on children and adolescents in Greece: the Healthy Growth Study

BACKGROUND

Some small cohort studies have noted that obesity co-exists with lower serum iron levels. The present study aimed to examine the association between being overweight and iron deficiency (ID) in a large cohort of Greek children and adolescents.

METHODS

A representative sample of 2492 primary schoolchildren aged 9-13 years old was examined. Anthropometric, biochemical, clinical, dietary intake and physical activity data were collected.

RESULTS

The prevalence of ID and iron deficiency anaemia (IDA) was higher in obese boys and girls compared to their normal-weight peers (P < 0.05). Serum ferritin was higher in obese compared to normal-weight boys (P = 0.024) and higher in obese compared to normal-weight and overweight girls (P = 0.001). By contrast, a negative association was found between transferrin saturation and adiposity in both boys and girls (P = 0.001 and P = 0.005). Furthermore, obese girls had significantly higher fibre intake than normal-weight girls (P = 0.048) and also overweight and obese boys and girls recorded significantly fewer pedometer steps than their normal-weight peers (P < 0.001). Finally, obesity more than doubled the likelihood of ID in both boys (odds ratio = 2.83; 95% confidence inteval = 1.65-4.85) and girls (odds ratio = 2.03; 95% confidence interval = 1.08-3.81) after controlling for certain lifestyle and clinical indices as potential confounders.

CONCLUSIONS

The present study shows that obese children and adolescents were at greater risk for ID and IDA than their normal-weight peers. Low grade inflammation induced by excessive adiposity may be a reason for the observed low iron levels. This is also strengthened by the elevated serum ferritin levels, comprising an acute phase protein that is plausibly increased in inflammation.

Imbalanced nutrition of top-level swimmers

The aim of the present study was to monitor the nutritional status of 9 Greek national top-level swimmers during a competitive season of eight months. The swimmers were assessed through recording of food and supplement intake, blood sampling, and anthropometry at four landmarks: in the beginning of the season (baseline), after completing a phase of intensive and voluminous training (at 10 weeks), at a minor taper (19 weeks), and during the major taper (32 weeks). Energy and macronutrient intake did not change significantly over time, and only a few significant changes were found in micronutrient intakes. Low carbohydrate and high fat intakes (e.g., 36 and 42 % of total energy, respectively, in males), inadequate intake of some micronutrients, and improper use of supplements indicated suboptimal dietary habits. Blood hemoglobin fluctuated significantly during the season. No significant changes in parameters indicative of the iron stores (transferrin saturation and ferritin) were found, although iron intake increased by supplementation with the onset of training. Serum markers of training stress were not significantly altered. In conclusion, Greek top-level swimmers should be guided toward a balanced diet and a rational use of supplements. Monitoring of dietary intakes during a competitive season is highly recommended.

Changes of plasma fibrinogen and fibrinolysis in response to competition stress in swimming coaches

AIM

The aim of the paper is to investigate the effects of competition stress in swimming coaches.

METHODS

The effect of competition stress on fibrinogen and t-PA antigen concentrations was studied in 14 coaches during an international swimming meeting. Three blood samples were collected at the 1st day of the swimming meeting: a) 30 min before the start of the 1st event of the morning session, b) 10 min before the start of the most important event, and c) during the event itself. These were analyzed for plasma fibrinogen and t-PA antigen.

RESULTS

An increase of plasma fibrinogen and t-PA antigen was observed during the race compared to 30 min before the start of the 1st day's event and 10 min before the race.

CONCLUSION

It is concluded that competition stress in a very important event has significant effects on plasma fibrinogen and t-PA antigen concentrations.

Effects of Iron Intake Through Food or Supplement on Iron Status and Performance of Healthy Adolescent Swimmers During a Training Season

Maintenance of a normal iron status is important for swimming performance during training and competition. The purpose of this study was to investigate whether 1) the iron status of healthy adolescent swimmers changes during a training season of six months, and 2) increasing daily iron intake affects iron status or performance. Forty-two (21 male and 21 female) swimmers, aged 12 - 17, without anemia or iron deficiency were divided into three equal groups. Group A received an iron supplement of 47 mg per day, group B followed a dietary plan rich in iron (providing, on average, 26 mg per day), and group C had a regular diet. Blood samples were taken before the beginning of the study and at the end of each of three training phases (moderate intensity training, high intensity training, and tapering) for the determination of hematological and iron status parameters. To evaluate performance, swimming tests at different distances were conducted along with blood sampling. The results showed significant fluctuations of iron status during the training season, including an increase in erythrocyte parameters during moderate intensity training. No significant differences in iron status or performance were found among the three groups. In conclusion, iron status and performance of healthy adolescent swimmers were affected by training irrespective of iron intake ranging from one to over five times the RDA over a period of six months.

Hematologic and biochemical profile of juvenile and adult athletes of both sexes: implications for clinical evaluation

The aim of the present study was to compare the values of seventeen hematologic and biochemical parameters between juvenile and adult athletes and non-athletes of both sexes. 579 athletes and 241 non-athletes participated in the study. We measured packed-cell volume, hemoglobin, red blood cell count, white blood cell count, platelet count, iron, glucose, urea, triacylglycerols, total cholesterol, high-density lipoprotein cholesterol, total/high-density lipoprotein cholesterol ratio, calcium, magnesium, creatine kinase, as well as alanine and aspartate aminotransferases. We found significant differences according to age, sex, and physical activity in the majority of the parameters. The effect size of physical activity on most parameters was small (< 0.5); however, that on packed-cell volume, glucose, urea, calcium, magnesium, and creatine kinase was moderate to high (0.5 to 0.8). It is remarkable that three of the highest effect sizes of physical activity appeared on parameters thought to be under tight homeostatic control (i. e., glucose, calcium, and magnesium). We conclude that physical training influences most of the biochemical parameters routinely measured in athletes, although, in some cases, its effect appears to be of limited biological importance. Therefore, clinical assessment on the basis of blood tests has to take into account not only the age and sex, but also the training status of individuals.