High blood pressure (Hypertension) is a common problem with a reported prevalence of around 30%. It is a common underlying cause of heart attacks, strokes and chronic kidney disease. What is the effect of winter on blood pressure has been an interesting subject of discussion.
It is a well-known fact that BP is invariably higher in colder months than in summer. This is true for both persons with hypertension and those with normal BP.
The reasons for this are multiple: Activation of body hormones like catecholamines (adrenaline, nor-adrenaline, etc) during cold, leads to increase in heart rate and constriction of blood vessels. In addition, the production of healthy hormones like nitric oxide which relaxes the arteries goes down.
The other factor linked to it is lower vitamin D levels because of less exposure to sunlight which leads to hormonal imbalance and activating kidney factors leading to higher BP readings. This combines with the other mechanisms leading to BP getting out of control even in those where it was well maintained during the summer months. Vitamin D supplements in winters are therefore recommended.
Raised levels of cholesterol even with a modest increase is an independent cause of increased BP, irrespective of age and the diabetic status etc. This again leads to the blood vessels getting constricted with reduction in the levels of protective hormones coming out from the blood vessel walls.
Physical activities in winter in general are considerably reduced and this again leads to increased BP. Exercise and the stress produced by this is very healthy for the blood vessels in the form of releasing good hormones.
Air pollution coming out of increased particulate materials, wood and fuel burning in particular to give warmth is an important factor which is injurious to the vessel walls leading to their getting constricted. This happens often when there are stagnant air columns in very low temperatures with low wind speed.
