How much are percents for general risk factors of atherosclerosis?Physiologic factors that increase risk
Various anatomic, physiological & behavioral risk factors for atherosclerosis are known. These can be divided into various categories: congenital vs acquired, modifiable or not, classical or non-classical. The points labelled '+' in the following list form the core components of "metabolic syndrome":
* Advanced age
* Having Diabetes or Impaired glucose tolerance (IGT) +
* Dyslipoproteinemia (unhealthy patterns of serum proteins carrying fats & cholesterol): +
o High serum concentration of low-density lipoprotein (LDL, "bad if elevated concentrations and small"), and / or very low density lipoprotein (VLDL) particles, i.e., "lipoprotein subclass analysis"
o Low serum concentration of functioning high density lipoprotein (HDL "protective if large and high enough" particles), i.e., "lipoprotein subclass analysis"
o An LDL:HDL ratio greater than 3:1
* Male sex
* Tobacco smoking
* Having high blood pressure +
* Being obese (in particular central obesity, also referred to as abdominal or male-type obesity) +
* A sedentary lifestyle
* Having close relatives who have had some complication of atherosclerosis (eg. coronary heart disease or stroke)
* Elevated serum levels of triglycerides +
* Elevated serum levels of homocysteine
* Elevated serum levels of uric acid (also responsible for gout)
* Elevated serum fibrinogen concentrations
* Elevated serum lipoprotein(a) concentrations
* Elevated serum C-reactive protein concentrations
o Chronic systemic inflammation as reflected by upper normal WBC concentrations, elevated hs-CRP and many other blood chemistry markers, most only research level at present, not clinically done.
* Stress or symptoms of clinical depression
* Hyperthyroidism (an over-active thyroid)
Dietary risk factors
The relation between dietary fat and atherosclerosis is a contentious field. The USDA, in its food pyramid, promotes a low-fat diet, based largely on its view that fat in the diet is atherogenic. The American Heart Association, the American Diabetes Association and the National Cholesterol Education Program make similar recommendations. In contrast, Prof Walter Willett (Harvard School of Public Health, PI of the second Nurses' Health Study) recommends much higher levels, especially of monounsaturated and polyunsaturated fat.Writing in Science, Gary Taubes detailed that political considerations played into the recommendations of government bodies. These differing views reach a consensus, though, against consumption of trans fats.
The role of dietary oxidized fats / lipid peroxidation (rancid fats) in humans is not clear. Laboratory animals fed rancid fats develop atherosclerosis. Rats fed DHA-containing oils experienced marked disruptions to their antioxidant systems, as well as accumulated significant amounts of peroxide in their blood, livers and kidneys. In another study, rabbits fed atherogenic diets containing various oils were found to undergo the greatest amount of oxidative susceptibility of LDL via polyunsaturated oils. In a study involving rabbits fed heated soybean oil, "grossly induced atherosclerosis and marked liver damage were histologically and clinically demonstrated".
Rancid fats and oils taste very bad even in small amounts; people avoid eating them. It is very difficult to measure or estimate the actual human consumption of these substances. In addition, the majority of oils consumed in the United States are refined, bleached, deodorized and degummed by manufacturers. The resultant oils are colorless, odorless, tasteless and have a longer shelf life than their unrefined counterparts. This extensive processing serves to make peroxidated, rancid oils much more elusive to detection via the various human senses than the unprocessed alternatives. |
