High LDL Cholesterol in Young Adults and Heart Disease Risk in Middle Age
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HIGH LDL CHOLESTEROL IN YOUNG ADULTS AND HEART DISEASE IN MIDDLE AGE
Most young adults look upon heart disease as an “old person’s” disease, and many young people therefore assume that they do not need to be concerned with their diet, or with their cholesterol profile, during this early stage of their adult lives. However, a newly published prospective public health study, which appears in the current issue of the Annals of Internal Medicine, should certainly cause young adults to reconsider the relevance of these two very important health-related factors to them.
In this study, 3,258 men and women between the ages of 18 and 30 enrolled in the Coronary Artery Risk Development in Young Adults (CARDIA) study between 1985 and 1986. All of these research volunteers underwent blood tests for LDL cholesterol (the “bad cholesterol”), HDL cholesterol (the “good cholesterol”), and triglycerides (fat in the blood, which is also linked to cardiovascular disease risk). Subsequently, these blood lipid tests were repeated throughout the 20-year course of this prospective public health research study. Twenty years later, these now middle-aged adults underwent special scans of their hearts in order to detect and quantify calcium deposits in their coronary arteries (the “coronary calcium score” is used to predict a patient’s risk of experiencing future cardiac events like angina or heart attack).
The findings of this study are cause for considerable concern. First of all, fully 87 percent of these volunteers were found to already have one or more abnormalities in their HDL, LDL or/and triglyceride levels, which are associated with an increased risk of cardiovascular disease. Thus, nearly 90 percent of these young adults, who were recruited into this research study from nearby communities at 4 different locations in the United States, already had abnormal blood lipid test results at the time they entered into this clinical study!
After 20 years of observation, coronary calcium scores were obtained on each of these more than 3,000 study participants. Once again, the results were striking (and concerning). When the average LDL levels of these study volunteers were compared with their calcium scores, it quickly became apparent that elevation of LDL levels in the blood during young adulthood is associated with a rising and significant risk of coronary artery disease during middle age (based upon coronary calcium score results). Among the volunteers who maintained normal LDL levels (<70 mg/dL, or <1.81 mmol/L) during their young adult years, there was an 8 percent incidence of coronary artery calcification (coronary artery atherosclerosis) 20 years later. However, among the patients with elevated average LDL levels (160 mg/dL or higher, or 4.14 mmol/L or higher), the incidence of coronary artery disease was 44 percent.
Even relatively mild increases in LDL levels during young adulthood were found, in this study, to be associated with an increased risk of coronary artery disease in mid-life. When compared to patients with LDL levels <70 mg/dL (<1.81 mmol/L), patients with LDL levels of 70 to 99 mg/dL (1.81 to 2.56 mmol/L) were 50 percent more likely to have detectable coronary artery disease. Patients with LDL levels between 100 and 129 mg/dL (2.59 to 3.34 mmol/L) were found have a 140 percent increased risk of coronary artery calcifications. Patients with LDL levels between 130 and 159 mg/dL (3.37 to 4.12 mmol/L) experienced a 230 percent increased risk of developing coronary artery disease in middle age. Finally, those patients with LDL levels of 160 mg/dl or higher (4.14 mmol/L or higher) had a whopping 460 percent increase in the risk of developing coronary artery disease by the time they reached middle age!
While the finding of coronary artery calcifications in these volunteers does not mean that every one of them will go on to experience heart attacks, or other serious complications of coronary artery disease, coronary artery calcium deposits (due to atherosclerosis) have been proven to significantly increase the risk of angina and heart attack, as well as other complications of cardiovascular disease.
This is a powerful public health study, because of its long-term follow-up of a relatively large group of patient volunteers. Its findings tell us at least two very important things that we all should know regarding the risk of developing cardiovascular disease during middle age. The first is that a strikingly large majority of young adults in the United States are already overweight, and already have abnormal blood lipid levels (and which are known to be associated with an increased lifetime risk of cardiovascular disease). Secondly, even relatively mild increases in the level of LDL cholesterol in the blood during early adulthood are associated with a significant increase in the likelihood of having heart disease by middle age. Moreover, significantly elevated LDL levels, over time, are associated with a huge increase in the risk of developing coronary artery disease by mid-life.
Based upon the findings of this important study, it is may be necessary to revisit the recommended age at which the routine annual testing of LDL cholesterol levels is initiated, particularly for young adults who are obese, or who have a family history of cardiovascular disease. I also cannot stress enough the direct linkages that exist between diet and weight, on the one hand, and LDL cholesterol levels on the other had. We are facing a true epidemic of obesity in this country, with two-thirds of the population already categorized as overweight or obese (and the proportion of the American population that is overweight or obese continues to rise every year). The results of this study add to other prior research data regarding the lifetime health effects of poor lifestyle and diet choices, even when these poor choices are made during the very early years of our adult lives.
For a disturbing look at the links between obesity and cancer risk, watch for the publication of my new landmark evidence-based book, “A Cancer Prevention Guide for the Human Race,” in late August of this year.
Disclaimer: As always, my advice to readers is to seek the advice of your physician before making any significant changes in medications, diet, or level of physical activity
Dr. Wascher is an oncologic surgeon, a professor of surgery, a cancer researcher, an oncology consultant, and a widely published author
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