Lost relation between blood pressure and serum 25-hydroxyvitamin D

Area of Science:

• Endocrinology and Metabolism
• Cardiovascular Health
• Nutritional Science

Background:

• Low serum 25-hydroxyvitamin D (25(OH)D) levels are consistently associated with hypertension.
• A significant, unexplained reduction in blood pressure (BP) has been observed in Western countries over recent decades.
• The relationship between 25(OH)D and BP requires updated investigation in light of these trends.

Purpose of the Study:

• To examine the association between serum 25-hydroxyvitamin D (25(OH)D) levels and blood pressure (BP).
• To analyze changes in the 25(OH)D-BP relationship over time using data from multiple Tromsø study surveys.
• To investigate potential confounding factors influencing the observed relationship.

Main Methods:

• Cross-sectional analysis of data from the 4th (1994/1995), 6th (2007/2008), and 7th (2015/2016) Tromsø surveys.
• Inclusion of 15,951 non-smoking subjects not using BP medication.
• Measurement of blood pressure and serum 25(OH)D levels, with adjustments for age and BMI.

Main Results:

• Unadjusted analyses showed a negative association between serum 25(OH)D and BP, which disappeared after confounder adjustment.
• Age- and BMI-adjusted analyses revealed a significant inverse relationship between BP and 25(OH)D in the 4th survey, a weaker association in the 6th, and no significant relationship in the 7th survey.
• For males, the difference in systolic BP between the lowest and highest 25(OH)D quartiles decreased from 6.2 mmHg in the 4th survey to -0.1 mmHg in the 7th survey.

Conclusions:

• A substantial reduction in population blood pressure occurred between 1994 and 2015.
• The relationship between serum 25(OH)D and BP has diminished over this period.
• The loss of this association is difficult to explain and warrants further research.