New risk factors and protective factors for cardiovascular diseases

Abstract

The prevalence of cardiovascular diseases (CVDs) has been increasing steeply due to various reasons, including both modern life style and ancient genes. Traditional risk factors for CVDs, such as obesity, lack of physical activity and smoking, are well known. These known risk factors do not explain a lot of the variance. We need to look at other things. Newer ideas include Human cytomegalovirus (HCMV) infection, hay fever, allergy and fatty acids, which may have potential influence on CVDs. Therefore, I study these related risk factors and protective factors.

Inflammation plays a important role in hypertension. Infection, inflammation and allergy are closely related to each other. In my study, the association of hypertension with HCMV infection and hay fever were investigated. HCMV seropositivity is associated with hypertension in women in NHANES population. This association between HCMV infection and hypertension is largely explained by the association of hypertension with age and the increase in past exposure to HCMV with age. In another study, previous diagnosis of hay fever was not associated with hypertension in adults overall. There is an association in subgroup of women aged 20–39 years before or after adjustment but not in other groups.

Hay fever is a kind of allergic rhinitis. Allergy was further studied. In both obesity and allergy, inflammation occurs. I explored the association of allergy with obesity. Serum IgE level is associated with waist circumference/body mass index (BMI). The attenuation in the association between IgE and waist circumference/BMI after controlling for liver enzymes and C-reactive protein suggests that hepatic inflammation may account for part of the association. Although allergy may not be the most consequential health risk for adult obesity, it does provide additional motivation to undertake the difficult challenge of fighting obesity.

Stroke is a severe outcome in CVDs and prevalent in the hypertensive population. After studying hypertension, I further studied the association of stroke with fatty acids including saturated fatty acids (SFAs) and unsaturated fatty acids (USFAs). The serum levels of the fatty acids including both USFAs (linoleic acid and nervonic acid) and SFAs (behenic acid and lignoceric acid) tested in our study were inversely associated with recent stroke. The inverse association of palmitoleic acid and palmitic acid levels with recent stroke was not significant after controlling for TC and TG, indicating these lipids may play a role in the association.

There are several clinical implications to have these new CVD factors-related studies performed. Knowing risk factors of CVDs may help people to avoid them and knowing protective factors may help people to adopt them, which may further reduce the prevalence of CVDs and save the healthcare burden. For example, if there is a causal link between obesity and allergy, efforts to control body weight may also be beneficial for the associated allergic diseases. Knowing both USFAs and SFAs may have beneficial effects in the reduction of stroke risk in the hypertensive population, people are suggested to adopt a balanced diet with both USFAs and SFAs.