Associations of 25-Hydroxyvitamin D With the Blood Pressure Response to Maximal Exercise Among Healthy Adults

Evaluation of normal range of serum 25 hydroxyvitamin d in iraqi healthy adults: demographic and socioeconomic effects

OBJECTIVE

Aim: To determine the normal range of serum levels of total 25(OH)VD in Iraqi healthy adult subjects and to relate its level with demographic profile and socioeconomic status..

PATIENTS AND METHODS

Materials and Methods: This cross sectional study was carried out at Iraq and the samples were collected during the period from August 2019 to January 2020. It included 649 adult subjects apparently healthy, from three governorates (Baghdad, Al-Anbar and Al-Basrah), Investigations included serum measurement of total 25(OH)D in all included individuals by using ELISA technique. Age, gender, marital state, blood pressure, smoking, sunshine exposure (%), hours of exposure/day, percentage of body surface area exposed, body mass index (BMI) subgroups, waist circumference (WC) subgroups, diet type, sport type and time, geographic factor (governorate) were measured and / or calculated and the levels of 25(OH)D were studied according to each of these factors.

RESULTS

Results: The mean ± SD level of 25(OH)D in total (n=649) studied Iraqi subjects was (16.29 ± 8.22 ng/ml), with women were significantly deficient than men (15.76 ± 6.89 ng/ml, 17.14 ± 6.85 ng/ml; p < 0.01 respectively). However, there was no significant differences in mean values of serum 25(OH)D levels among studied governorates, subgroups of BMI, WC, marital status, smokers and nonsmoker and subgroups of age. The mean value of serum 25(OH)D was found to be decreased in January, October and November as well as according to diet and sport types. There was significant positive correlation between total 25(OH)D and sun exposed surface area, sun exposure duration and with sun exposure area.

CONCLUSION

Conclusions: The mean (±SD) value of serum total 25(OH)D in Iraqi healthy subjects was 16.29 ng/ml (±8.22) reflecting the actual body status of this vitamin with lower concentration in women than in men. Type and time of sport and diet type were the major vitamin D dependent factors.

Association of 25-hydroxy vitamin D level with the blood pressure response to a maximum exercise test among professional indoor athletes

Purpose

Low vitamin D levels have been associated with elevated blood pressure (BP) in the general population. However, whether there is an association of vitamin D insufficiency with BP changes during maximum exercise in athletes is currently unclear.

Methods

A total of 120 male professional indoor athletes (age 26 ± 5 years) were examined. BP was measured at rest and during a graded cycling test. We assessed the BP response (BPR) during maximum exercise and the respective load. BP and BPR (peak-baseline BP) were analysed with respect to 25-OH vitamin D levels, with levels < 30 ng/mL defining vitamin D insufficiency.

Results

35 athletes were classified as being vitamin D insufficient. BP was not different between sufficient and insufficient vitamin D groups (122 ± 10/75 ± 7 vs. 120 ± 12/77 ± 9 mmHg). At maximum exercise, however, systolic BP (198 ± 17 vs. 189 ± 19, p = 0.026) and the pulse pressure (118 ± 18 vs. 109 ± 21 mmHg, p = 0.021) were higher in the sufficient group; the BPR was not different between groups (76 ± 20/5 ± 6 vs. 69 ± 22/3 ± 6 mmHg, p = 0.103). Athletes with sufficient levels had a higher maximum power output (3.99 ± 0.82 vs. 3.58 ± 0.78 W/kg, p = 0.015) and achieved higher workloads (367 ± 78 vs. 333 ± 80 W, p = 0.003). The workload-adjusted BPR (maximum systolic BP/MPO) was not different between athletes with sufficient and insufficient vitamin D levels (51 ± 10 vs. 56 ± 14 mmHg × kg/W, p = 0.079).

Conclusion

Athletes with sufficient vitamin D achieved a higher maximum systolic BP and a higher maximum power output. The workload-adjusted BPR was not different between groups, which suggests that this finding reflects a better performance of athletes with sufficient vitamin D.

Association of Serum Levels of Vitamin D with Blood Pressure Status in Northern Iranian Population: The PERSIAN Guilan Cohort Study (PGCS)

Background

Evidence in the last decades has indicated an association between vitamin D and cardiovascular risk factors including blood pressure. The present study aimed to determine whether serum 25-hydroxyvitamin D is independently associated with blood pressure in a large population-based study.

Methods

The study was based on subjects from PERSIAN Guilan Cohort Study (PGCS), a prospective, population-based cohort study in Guilan, Iran. In 9520 men and women, aged 35-70 years, serum 25-hydroxyvitamin D, systolic and diastolic blood pressure were measured. Multiple logistic and linear regression analyses were conducted with adjustments for demographic factors (age and gender), anthropometric characteristics (waist circumference and body mass index), lifestyle variables (physical activity, alcohol, and smoking consumption), and renal function (serum creatinine).

Results

Fully adjusted linear regression analyses revealed a weak but statistically significant negative association between serum 25-hydroxyvitamin D levels and systolic blood pressure (β = -0.02, 95% CI= -0.052 to -0.0001, P-value=0.04), whereas vitamin D status was not significantly associated with diastolic blood pressure (β = -0.01, 95% CI= -0.026 to 0.009, P-value=0.3). Serum 25-hydroxyvitamin D status showed no significant association with the presence of hypertension (OR 1.09, 95% CI=0.94 to 1.25 for the lowest (25OHD <12 ng/mL) versus the highest (25OHD ≥20 ng/mL) category).

Conclusion

Lower serum vitamin 25 (OH) D levels were associated with higher systolic blood pressure; however, it was not associated with diastolic blood pressure and presence of hypertension.