Best of Dietary Fiber and Heart DiseaseDecember 30, 2010 Written by JP [Font too small?]
Some people like to play board games, watch sporting events or knit in their spare time. Me? I like to browse around the Centers for Disease Control and Prevention web site. I sometimes search around there for statistics that help shape the content that ends up here. The other day I found a few interesting facts and figures. I already knew that heart disease is the “leading cause of death for both women and men in the United States”. But I was still stunned by a few other statistics. In 2005, 7.6 million people’s lives ended prematurely due to coronary heart disease. In 2003, almost 40% of adults exhibited two or more of six risk factors for heart disease and stroke (diabetes, high blood pressure, high cholesterol, obesity, physical inactivity and smoking). These figures have probably only gotten worse in the time since they were compiled. This is evidenced by the most recent figure available: “In 2009, heart disease is projected to cost more than $304 billion dollars, including health care services, medications and lost productivity.”
Several months ago I wrote a column highlighting recent evidence that a high fiber diet can help protect against a variety of cancers. Today I’ll focus on the role that this dietary component can play in helping to reduce the risk of developing cardiovascular disease and all of its related complications.
In July 2010, a study appeared in the Journal of Epidemiological Community Health. 772 volunteers who were at high risk for cardiovascular disease participated in this trial. They were all assigned either a low fat diet or one of two “Mediterranean style diets” for a 3 month period. Dietary questionnaires were administered to determine nutrient intake and blood tests were taken pre and post trial.
- The volunteers who consumed the most fiber (the upper 20%) showed the greatest declines in fasting blood sugar and total cholesterol. They also demonstrated higher HDL “good” cholesterol readings.
- LDL “bad” cholesterol only dropped significantly in those who ate the largest quantities of soluble fiber, which is found in such as foods as berries, broccoli, chia and psyllium seed supplements.
- Reductions in C-reactive protein, an inflammatory marker, were also found in those consuming the largest amount of fiber.
The authors of the trial concluded that, “increasing dietary fiber intake with natural foods is associated with reductions in classical and novel cardiovascular risk factors in a high-risk cohort”. (1)
Another recent study presented in the European Journal of Clinical Nutrition determined that eating foods rich in any kind of fiber (insoluble, soluble or total fiber) may result in a reduced likelihood of stroke by up to 36%. These findings are based on a population study of over 26,000 Finnish male smokers with ages ranging from 50 – 69. This is, again, considered a high-risk group that apparently was afforded potentially life saving support via adequate to optimal fiber consumption. (2)
If dietary fiber does, in fact, protect from cardiovascular disease, then there must be a mechanism behind its ability to do so. Here are some of the proposed ways that roughage may shield against heart disease and strokes.
- Blood Pressure - Both population and scientifically controlled studies frequently find that higher levels of dietary fiber are associated with lower blood pressure (BP) readings – a risk factor for both heart disease and stroke. A current study also discovered that replacing a low fiber, refined bread with a higher fiber bread resulted in decreased systolic BP and pulse pressure. (3,4,5)
- Chronic Inflammation - A recent scientific review of the medical literature examined 7 studies that related to fiber consumption and levels of the inflammatory marker, C-reactive protein (CRP). CRP may contribute to hardening of the arteries (atherosclerosis) and the accumulation of arterial plaque which can lead to heart attacks and stroke. 6 of 7 trials reported 25 – 54% reductions in CRP concentrations in those supplementing with fiber. Another trial, which followed 3,428 men (aged 60 – 79) over the course of 7 years, found that higher fiber intake not only reduced CRP levels, but also lowered other inflammatory markers (interleukin-6 [IL-6]), decreased fat build up in the liver and appeared to reduce the risk of developing diabetes. (6,7,8)
- Elevated Cholesterol - Adding fiber supplements to conventional cholesterol lowering therapy (statin medications) has an additive effect and results in greater reductions in total cholesterol, LDL cholesterol and Apo B. Since I’m not a supporter of statin medications, I was relieved to learn that this same form of fiber (hydroxypropylmethylcellulose – HPMC) can effectively lower cholesterol without any pharmaceutical assistance as well. Other forms of fiber, such as beta glucans derived from oats, are also effective in improving lipid profiles. (9,10,11)
- Metabolic Syndrome and Diabetes - Out of control blood sugar is a major health threat which contributes to many medical conditions. Including plenty of fibrous food and supplements in one’s daily routine can help temper post meal blood sugar response. In essence, it slows the digestion of carbohydrates and simple sugars. This is in turn helps to support arterial function and blood flow which is impaired by a poor diet that promotes cardiovascular disease. One of my favorite studies of late involves a group of American Samoans who replaced their “modern eating habits” with a traditional Samoan meal plan (rich in coconut, fish and various sources of “plant-based fiber”). This dietary shift resulted in numerous heart-healthy changes: an increase in HDL “good” cholesterol, reduced abdominal fat and metabolic syndrome risk factors (elevated blood lipids, high blood pressure and insulin and mid-section obesity). (12,13,14,15,16,17,18)
Chronic Inflammation Impacts Cardiovascular Health and More
- Weight Management - Over the last few years, numerous studies have determined that pre-loading with fiber or consuming more fiber rich foods tends to decrease appetite and promote a healthier weight. Obesity is one of the strongest established risk factors associated with cardiovascular disease. Consuming dietary fiber can promote feelings of satiety by expanding in the stomach (creating a full feeling), calming blood sugar response to food and even modifying the levels of gut hormones that relay hunger and satisfaction signals to the brain. (19,20,21,22,23,24)
There are likely to be other factors involved in the fiber-heart connection. For instance, it was recently noted that high fiber diets were inversely related to an unhealthy thickening of the arteries or carotid intima-media thickness. One theory why is that dietary roughage appears to help regulate calcium levels in the body. Calcium build up in the arteries is now believed to be a major factor in the progression of cardiovascular disease. Those who do not have significant calcium accumulation in the circulatory system appear to be at very low risk of having a heart attack or stroke. (25,26,27,28,29)
The statistics at the beginning of this column are certainly cause for alarm. Heart disease is, in fact, a real threat to worldwide wellness. But what’s also true is that most of the risk factors for cardiovascular disease seem to be modifiable. Thankfully, many of these necessary changes are available to us all. They don’t require a doctor’s prescription pad or a high tech hospital to proceed. But as with all things in life, there are trade-offs. Changing diet and living a protective lifestyle requires a conscious effort. I hope the evidence presented today will provide you with the necessary incentive to make that effort and reap the rewards that I believe it will bring. (30)
Update: December 2010 - The positive news about dietary fiber and cardiovascular disease continues its forward march. New research presented in three separate medical journals helps to bolster the case for including more roughage in your diet in relation to heart health. The December issue of Applied Physiology, Nutrition and Metabolism describes how the addition of soluble fiber to fruit juice can lead to meaningful changes in body fat percentage, body weight and waist circumference in obese individuals. The supplemental fiber appears to accomplish this feat by improving glucose metabolism. As a bonus, the added fiber also resulted in a reduction in LDL (“bad”) cholesterol and triglycerides and a welcome elevation in HDL (“good”) cholesterol. Two other publications in the journals Magnesium Research and Nutrition offer up an indirect pathway by which dietary fiber may improve cardiovascular wellness: by simultaneously increasing magnesium intake. Recent findings indicate that choosing foods that are rich in fiber also tends to elevate dietary exposure to heart-friendly minerals including magnesium. A large body of evidence suggests that a lack of this essential mineral can lead to chronic inflammation which can damage the heart. (31,32,33)
Note: Please check out the “Comments & Updates” section of this blog – at the bottom of the page. You can find the latest research about this topic there!
Tags: Cholesterol, Fiber, High Blood Pressure
Posted in Food and Drink, Heart Health, Nutrition