Vitamin D & the Prevention of Colon & Rectal Polyps
By, Robert A. Wascher, MD, FACS
The information in this column is intended for informational purposes only, and does not constitute medical advice or recommendations by the author. Please consult with your physician before making any lifestyle or medication changes, or if you have any other concerns regarding your health.
STRESS & YOUR RISK OF HEART ATTACK
There is a great deal of anecdotal observation linking prolonged levels of increased stress with cardiovascular events such as angina (chest pain due to narrowed coronary arteries), heart attack, stroke, and death due to these conditions. The precise mechanisms whereby chronic psychological stress increase cardiovascular-related disease and death are not completely understood at this time. During this prolonged period of pervasive stress and distress, as our nation confronts the worst economic crisis since the Great Depression, a timely research study on the topic of psychological stress and cardiovascular disease risk has just been published in the Journal of the American College of Cardiology.
In this prospectively conducted study, 6,576 clinically healthy men and women, with an average age of 50 years, were followed for an average of 7.2 years. At the onset of this clinical research study, extensive psychological and physiological and laboratory profiles were obtained on each patient volunteer. These profiles included previously validated psychological, behavioral and physical health questionnaires, as well as laboratory testing for C-reactive protein, cholesterol levels, and other cardiovascular disease risk factors. All patient volunteers were also evaluated for evidence of obesity and high blood pressure. After completing this comprehensive assessment of potential cardiovascular disease risk factors, these 6,576 men and women were carefully observed, for an average of 7 years, for the new onset of acute cardiovascular disease events, including heart attack (myocardial infarction) or the urgent need for angioplasty or coronary artery bypass surgery; as well as for the new onset of heart failure, stroke, or death due to an acute cardiovascular event.
During the course of this study, this cohort of middle-aged men and women experienced 223 acute cardiovascular events, 63 of which were fatal. The results of this clinical study, after analyzing the large amount of data collected, were both intriguing and instructive. First of all, high levels of psychological distress were closely linked with the following behavioral and physiological factors: an increased likelihood of smoking cigarettes, reduced levels of physical activity and exercise, elevated levels of serum C-reactive protein, and high blood pressure. A closer analysis of these same stress-associated factors revealed an even more important finding. The majority of the observed stress-associated risk for acute cardiovascular events was directly related to behavioral activities, while only a minority of the overall stress-related risk was linked to non-behavioral physiological causes.
Altogether, approximately 65 percent of the stress-associated risk for cardiovascular disease events in this large group of patient volunteers was linked to behavioral choices on the part of individuals, including an increase incidence of cigarette smoking and a decreased level of physical activity and exercise. Stress-related hypertension was judged to contribute about 13 percent of the overall risk of acute cardiovascular events observed in this study, while increased levels of the inflammatory C-reactive protein appeared to contribute to approximately 6 percent of the risk (both blood pressure and C-reactive protein levels have long been known to rise in response to stress, as well as in response to smoking).
This study is important, and for several reasons. In this study, the development of cardiovascular events, including death, were carefully followed in a thoroughly evaluated cohort of initially health middle-aged men and women, and this large group of patient volunteers were followed for, on average, the better part of a decade. All patient volunteers were carefully and comprehensively evaluated for both psychological and physiological abnormalities at the onset of the study. These research methods, therefore, provided a very rich and powerful set of data upon which this study’s conclusions are based.
We have long known that prolonged levels of psychological stress directly affect circulating levels of hormones and other stress-response proteins that can accelerate the development of cardiovascular diseases. However, importantly, this study reveals that engaging in risky health-related behaviors appears to underlie the overwhelming majority of the increased risk for cardiovascular disease that is associated with psychological stress, rather than non-behavioral stress-related physiological changes.
The results of this study suggest that the majority of stress-related cardiovascular disease risks can probably still be prevented simply by maintaining a healthy lifestyle and, most importantly, by refraining from unhealthy behaviors that tempt us when times are tough, and when we are feeling stressed. Even when you are feeling stressed, as much of nation is currently experiencing during the ongoing economic crisis, please abstain from tobacco, minimize red meat and other fatty foods in your diet, and avail yourself to whatever forms of moderate and frequent exercise are available to you (at least 4 to 5 times per week). If you have high blood pressure, or elevated serum levels of C-reactive protein or cholesterol, then ask your doctor to develop a treatment plan for you, and stick with this plan! If you are one of the estimated 48 million people in this country who, shamefully, do not have health insurance (or one of the many millions more who have completely inadequate healthcare insurance), you can still improve your blood pressure, and serum cholesterol and C-reactive protein levels, by cutting the fat and excess calories from your diet, and by exercising regularly and frequently, and by avoiding tobacco and excessive alcohol. As an added benefit, engaging in these relatively modest healthy lifestyle behaviors, you will also increase your ability to psychologically and emotionally cope with the high levels of stress that many of us are feeling these days.
VITAMIN D & THE PREVENTION OF COLON & RECTAL POLYPS
As most readers of this column already know, I have a very strong interest in disease prevention through dietary and other and holistic lifestyle strategies. As an oncology physician, I have especially been interested in lifestyle and dietary approaches to cancer prevention (my new book, “A Cancer Prevention Guide for the Human Race,” should be available in the fall or winter of 2009).
Recently, several very large prospective, randomized, placebo-controlled cancer prevention trials have published their results regarding antioxidant vitamins and related dietary supplements, and the news from these large trials has been, uniformly, disappointing. However, while the putative cancer prevention properties of Vitamin E, Vitamin C, Vitamin A, beta-carotene and selenium are now in serious doubt, Vitamin D, which actually functions more like a hormone than a vitamin, continues to merit serious study as a potential cancer prevention aid (I should note, however, that a recent prospective randomized clinical trial has called into question a role for Vitamin D as a breast cancer prevention agent).
The two most important areas where Vitamin D continues to show some ongoing promise, in addition to its vital role in preserving skeletal health, are in the prevention of colorectal cancer and cardiovascular diseases. While the research data in this area remains somewhat contradictory, there are still several high-quality clinical research studies available that suggest a potential role for Vitamin D in reducing the risk of cancers of the colon and rectum (unfortunately, however, most of these studies rely upon relatively low-powered research methods).
Now, a newly published summary in the journal Cancer Epidemiology Biomarkers & Prevention provides important additional information regarding Vitamin D’s potential role in preventing the colon and rectal polyps that give rise to the vast majority of colorectal cancers.
In this meta-analysis study from Harvard University, 17 previously published epidemiological studies were reviewed and statistically evaluated. In particular, these 17 clinical studies evaluated the serum levels of Vitamin D, dietary intake of Vitamin D, and the incidence of precancerous adenomatous colorectal polyps in healthy patient volunteers.
Based upon the results of this meta-analysis, on average, patients with the highest levels of Vitamin in their blood were 30 percent less likely to be diagnosed with colorectal adenomas. When considering more advanced adenomas, which are much more likely to progress to colorectal cancer, patients with the highest levels of Vitamin D in the blood were 36 percent less likely to be diagnosed with this more aggressive type of polyp.
Increased dietary Vitamin D intake was also associated with a decrease in the risk of developing new or recurrent adenomatous polyps of the colon and rectum. However, the protective effect of increased dietary Vitamin D intake was not as robust as was observed in patients with measured high levels of this vitamin in their blood, and only a marginal decrease in colorectal polyp incidence was identified among patients who consumed higher levels of Vitamin D in their diet.
While the 17 previous research studies that were analyzed in this new report tended to rely upon lower-powered research methods, the findings of this analysis are in agreement with multiple other epidemiological studies that have identified a modest-to-moderate potential protective role against colorectal cancer for Vitamin D. However, I must caution readers that Vitamin D, like almost everything else in our diet, can be toxic in large quantities (or even in smaller quantities if you have kidney disease, parathyroid gland abnormalities, or other preexisting health conditions involving abnormal calcium or Vitamin D metabolism). Excessive intake of Vitamin D can result in serious health problems, and so I recommend that you only consider taking Vitamin D supplements above the current recommended range following consultation with your primary physician or an endocrinologist.