Lower adiponectin is associated with higher anthropometry and insulin resistance but not with low cardiorespiratory fitness in adolescents

PURPOSE

The aim of this study was to analyze the relationship between adiposity, cardiometabolic risk and cardiorespiratory fitness (CRF) according to different groups of adiponectin concentration.

METHODS

255 adolescents of both sexes, aged 11-17 years old, participated. Anthropometric and biochemical parameters such as body mass, height, abdominal circumference (AC), waist circumference (WC), fat mass, fat-free mass, total cholesterol (TC), high-density lipoprotein (HDL-c), low-density lipoprotein (LDL-c), triglycerides (TG), glucose, insulin, adiponectin, blood pressure, peak oxygen consumption (VO2peak) were measured. Body mass index (BMI), z-score BMI (BMI-z), triponderal mass index (TMI), waist-to-height ratio (WHtR), homeostasis model to assessment insulin resistance (HOMA-IR), and quantitative insulin sensitivity check index (QUICKI) were calculated. Adiponectin was categorized: low adiponectin concentration (LAC  ≤ 5.18 µg/mL-1), intermediate (IAC = 5.18 and 7.63 µg/mL-1) and high (HAC ≥ 7.63 µg/ml-1).

RESULTS

LAC showed higher BMI, BMI-z and TMI than the other groups (p < 0.05) and higher AC, WC and WHtR that the HAC (p < 0.05). IAC showed lower values of TC, LDL-c and TG, and the LAC presented the highest values of insulin, HOMA-IR and QUICKI (p < 0.05) to the IAC and HAC. HAC presented the lower VO2peak than the other groups (p < 0.01). BMI, TMI, glucose, insulin, HOMA-IR showed inverse, and QUICKI a direct and weak correlation with adiponectin (p < 0.05). No significant association was found between adiponectin and VO2peak (p > 0.05).

CONCLUSION

The LAC group had higher means in the anthropometric variables and the worst results related to insulin resistance and sensitivity. Thus, adiponectin may play an important role in obesity and reduced concentration may be a factor in the development of obesity-associated morbidities.

VITATOPS, the VITAmins TO prevent stroke trial: rationale and design of a randomised trial of B-vitamin therapy in patients with recent transient ischaemic attack or stroke (NCT00097669) (ISRCTN74743444)

BACKGROUND

Epidemiological studies suggest that raised plasma concentrations of total homocysteine (tHcy) may be a common, causal and treatable risk factor for atherothromboembolic ischaemic stroke, dementia and depression. Although tHcy can be lowered effectively with small doses of folic acid, vitamin B(12) and vitamin B(6), it is not known whether lowering tHcy, by means of B vitamin therapy, can prevent stroke and other major atherothromboembolic vascular events.

AIM

To determine whether the addition of B-vitamin supplements (folic acid 2 mg, B(6) 25 mg, B(12) 500 microg) to best medical and surgical management will reduce the combined incidence of stroke, myocardial infarction (MI) and vascular death in patients with recent stroke or transient ischaemic attack (TIA) of the brain or eye.

DESIGN

A prospective, international, multicentre, randomised, double blind, placebo-controlled clinical trial.

SETTING

One hundred and four medical centres in 20 countries on five continents.

SUBJECTS

Eight thousand (6600 recruited as of 5 January, 2006) patients with recent (<7 months) stroke (ischaemic or haemorrhagic) or TIA (brain or eye).

RANDOMISATION

Randomisation and data collection are performed by means of a central telephone service or secure internet site.

INTERVENTION

One tablet daily of either placebo or B vitamins (folic acid 2 mg, B(6) 25 mg, B(12) 500 mug).

PRIMARY OUTCOME

The composite of stroke, MI or death from any vascular cause, whichever occurs first. Outcome and serious adverse events are adjudicated blinded to treatment allocation.

SECONDARY OUTCOMES

TIA, unstable angina, revascularisation procedures, dementia, depression. STATISTICAL POWER: With 8000 patients followed up for a median of 2 years and an annual incidence of the primary outcome of 8% among patients assigned placebo, the study will have at least 80% power to detect a relative reduction of 15% in the incidence of the primary outcome among patients assigned B vitamins (to 6.8%/year), applying a two-tailed level of significance of 5%.

CONCLUSION

VITATOPS aims to recruit and follow-up 8000 patients between 1998 and 2008, and provide a reliable estimate of the safety and effectiveness of folic acid, vitamin B(12), and vitamin B(6) supplementation in reducing recurrent serious vascular events among a wide range of patients with TIA and stroke throughout the world.

Sustained Homocysteine-Lowering Effect over Time of Folic Acid-Based Multivitamin Therapy in Stroke Patients despite Increasing Folate Status in the Population

BACKGROUND AND AIMS

It is uncertain what impact increasing voluntary folate fortification may be having on the statistical power of randomized trials testing the homocysteine hypothesis of atherothrombosis. The objective of this study was to determine whether there has been a change in folate status between 1998 and 2002 in stroke patients randomized into the VITAmins TO Prevent Stroke (VITATOPS) Study at a single center in Perth, Australia, and what impact this may have had on the magnitude of the homocysteine-lowering effect achieved over time with folic acid-based multivitamin therapy.

METHODS

We conducted a randomized, double-blind, placebo-controlled study involving 285 patients with stroke or transient ischemic attack who were recruited between 1998 and 2002 and randomized to long-term folic acid 2.0 mg/day, pyridoxine 25 mg/day and cobalamin 0.5 mg/day (active VITATOPS medication) or placebo. Fasting plasma total homocysteine, red cell folate, serum cobalamin and serum pyridoxine levels were measured at baseline and 6 months, and the change in blood levels over 4 time quartiles and differences in levels between the two randomized treatments were examined.

RESULTS

Between 1998 and 2002, there was a significant rise in baseline mean red cell folate levels over 4 time quartiles among the entire stroke cohort (723.3, 780.1, 922.6 and 1,023.7 nmol/l in the first, second, third and fourth quartiles, respectively; p < 0.0001), but this was not associated with a spontaneous reduction in mean baseline total homocysteine levels during the same time period (12.7, 14.3, 12.1 and 12.8 micromol/l in the first, second, third and fourth quartiles, respectively; p = 0.55). The homocysteine-lowering effect of the active VITATOPS trial medication at 6 months after randomization also did not change significantly between 1998 and 2002 (difference between randomized groups: -4.1, -4.1, -3.1 and -3.6 micromol/l in the first, second, third and fourth quartiles, respectively; p = 0.56).

CONCLUSIONS

The homocysteine-lowering effect of the active VITATOPS trial medication has not attenuated significantly in the past 5 years despite increasing voluntary fortification of foods with folic acid as reflected by a progressive rise in baseline folate status. These data suggest that in the continuing absence of a program of mandatory folate fortification of food in populations served by centers participating in the VITATOPS trial, the study will remain adequately powered to test the homocysteine-lowering hypothesis for which it was designed.