Published December 18, 2011
If there’s something Americans understood, it is the message to avoid saturated fat if you want to prevent cardiovascular disease (CVD). However, nowadays there is more literature saying we were wrong. Were we?
The American Journal of Clinical Nutrition wrote: “During 5–23 y of follow-up of 347,747 subjects, 11,006 developed CHD or stroke. Intake of saturated fat was not associated with an increased risk of CHD, stroke, or CVD”, results from “ a meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease.”
What’s not in this message is one of the most powerful culprits of the rise of cardiovascular disease is the outrageous sugar consumption that prevails in the typical American diet. Given all the seemingly conflicting information out there, there’s still a lot that needs to be understood on the relationship between saturated fat and the incidence of cardiovascular disease.
When looking at the heart, nothing is quite simple. This proves to be right even after interviewing three renowned experts on this topic: Barry Sears, Ph.D., author of The Zone Diet; Erin Palinski, RD,CDE, LDN, CPT, nutritionist specializes in cardiovascular health; and Shana Maleef, MA, RD, CDN. Here’s what they have to say:
Hearty round table
Some experts who say that the evidence between saturated fat and CVD may have been biased because research didn’t take into account the sugar content of the diet. So can we think that sugar is the real culprit of developing CVD and not necessarily saturated fat intake.
Sears: Carbohydrates, especially high-glycemic carbohydrates, will increase insulin, and if the diet is rich in omega-6 fatty acids, the combination of these two events will increase cellular inflammation via the increase in pro-inflammatory hormones known as eicosanoids. These powerful inflammatory hormones are derived from arachidonic acid, which is an omega-6 fatty acid. It is cellular inflammation caused by increased arachidonic acid levels that is the real culprit for CVD. This is why aspirin is effective for preventing a heart attack even though it doesn’t lower cholesterol.
Palinski: Although new studies do show the saturated fat may not have as big an impact on CVD as once thought, foods high in saturated fat may increase inflammation in the body, increasing the risk for CVD. Foods high in saturated fat also tend to be higher overall in calories. Excessive caloric intake can increase visceral fat in the abdomen, which can increase CVD risk.
Maleef: Both sugar and saturated fats (in addition to other harmful nutrients, like trans fats, cholesterol, and sodium) contribute to the development of CVD. CVD can develop and progress for various reasons and the causes are different for each individual. CVD develops as a result of a person’s genetic risk factors in addition to other risk factors, like cholesterol levels, smoking, weight, activity level, etc. So sugar may play a role in the development of CVD (especially for people who are overweight, insulin resistant, or diabetic, for example) but saturated and trans fats absolutely play a role for all in increasing risk.
Likewise, new studies are showing that eating cholesterol doesn’t necessarily increase blood cholesterol levels. We see that nowadays there is more support to eat eggs as a part of a healthy diet. Does eating cholesterol really impact cholesterol level?
Maleeff: Eating dietary cholesterol does impact cholesterol levels, however not as much as saturated and trans fats impact cholesterol levels. Therefore, we encourage people to look at these harmful dietary fats more than at dietary cholesterol. Both are important to be aware of, though.
Sears: Dietary cholesterol has little effect on CVD. However, oxidized cholesterol found in LDL – popularly known as “bad cholesterol”- particles has a significant impact on the development of CVD. Eating egg whites is a great dietary choice, but egg yolks that are very rich in arachidonic acid should be avoided since that will generate increased cellular inflammation.
Palinski: Dietary cholesterol has a minimal intake on total cholesterol levels. A diet higher in processed foods high in refined carbohydrates and trans fats may raise cholesterol levels higher than total cholesterol. I also always tell my patients many times cholesterol is high due to what we are NOT eating rather then what we are eating. A diet high in healthy, unsaturated fats including monounsaturated fats and omega 3 fatty acids as well as a diet high in soluble fiber will help to regulate cholesterol levels.
Will the impact of cholesterol depend on other nutrients that the food contains?
Sears: If the meal is rich in polyphenols (the chemicals that give fruits and vegetables their color), then they reduce the oxidization of cholesterol rendering the amount of cholesterol in the diet to be virtually meaningless.
Palinski: Yes, the intake of B vitamins will help to lower homocystine levels, omega 3 can help to lower triglyceride levels, and limiting foods high in refined carbohydrates can help to reduce triglycerides –TG- levels as well. Also, foods high in soluble fiber, such as vegetables, fruits, oats, etc can also help to reduce bad cholesterol levels.
Some experts agree that the role of assessing total blood cholesterol as an important indicator when looking for CVD risk is no longer one of the best values. What are the best indicators then?
Sears: One of the best common markers is the ratio of TG/HDL – popularly known as “good cholesterol”- as it is an indicator of insulin resistance. A much better marker than LDL cholesterol is oxidized LDL cholesterol which is rarely tested. However, the best marker maybe the ratio of the molecular building blocks for pro-inflammatory and anti-inflammatory eicosanoids. This is tested by the ratio of two fatty acids (arachidonic acid and eicosapentaenoic acid) in the blood that can analyzed from a simple finger prick.
Maleeff: Total cholesterol is not a very reliable indicator of CVD risk, because total cholesterol is a formula derived from LDL, HDL, and triglyceride levels. Therefore, someone can have a high total cholesterol simply because they have a very high level of HDL “good” cholesterol, and conversely they may have a seemingly normal total cholesterol level when their HDL is low, but LDL and/or triglycerides are high. It is best to look at each marker individually – HDL, LDL, and triglycerides. In addition, there are a number of advanced risk markers which indicate size of HDL and LDL particles, inflammatory markers (like CRP and LPPLA2), insulin, and genetic markers.
Palinski: Visceral fat in the abdomen can be a big indicator of CVD, so waist and waist to hip ratio measurements are important. Inflammatory markers such as C-reactive protein and homecystine levels may also indicate increase risk of CVD.
After this overview on the relationship between saturated fat and cholesterol intake and CVD, if something looks clear is that there’s still a lot to be studied to get a consensus on which dietary habits have the most impact on the risk of heart disease and on how to asses CVD. Meanwhile, proceed with caution when eating certain types of fats and avoid sugary processed food. And, don’t be afraid to ask your doctor to check other blood values that go beyond the traditional total cholesterol.
When in doubt on how to approach fat intake, this is what Sears advises as the correct health ranking of fats from best to worst: Long-chain omega-3 fats (EPA and DHA) > short chain-omega-3 (flaxseed oil) > monounsaturated fats (olive oil) > long-chain saturated fats (stearic acid) > short chain saturated fats > medium chain saturated fats (lauric, myristic, and palmitic) > omega-6 fats > arachidonic acid. (usually found in dressings, chips, fast food and some oils like vegetable and soy oils.).
Marta Montenegro is an exercise physiologist, certified strength and conditioning, coach and master trainer who is an adjunct professor at Florida International University. Marta has developed her own system of exercises used by professional athletes. Her personal website martamontenegro.com, combines fitness, nutrition and health tips, exercise routines, recipes and the latest news to help you change your life but not your lifestyle. She was the founder of nationally awarded SOBeFiT magazine and the fitness DVD series Montenegro Method.