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ARE VEGETABLE OILS HEALTHY?

25.09.2014 / By Sonia Raga / Published in NUTRITION

 

Pouring oil into a bowl

 

We always thought vegetable oils are part of a healthy diet but…what does the medical literature have to say about it?

In this post I put some information together about the adverse effects of excess fat consumption but I focus mainly on why it is important to avoid oils or to keep them to a minimum. Everything stated here is not my opinion but data and studies collected from different sources, all cited at the end of the post.

FACTS

Vegetable oils have good reputation because they have less saturated fat than animal fat.

  • They are though, loaded with calories. Since vegetable oils are pure fat, they contain 9 calories per gram, more than twice the content of carbohydrate and protein (4 calories per gram).
  • If your goal is to regain as much insuline sensitivity as possible, you will want to eliminate not only animal fats but also added vegetable oils.
  • For people who suffer from heart disease and/or diabetes, many doctors recommend to follow a low fat diet, avoiding animal products and oils.

 

But aren´t those fats the good kind?

Let´s take olive oil as an example. It doesn´t matter if it´s olive oil, extra virgen olive oil, cold press extra virgin olive oil…The quality won´t change the amount of fat in a tablespoon. 100% fat. Think of how olive oil is made (or any other oil whatsoever). They take a big amount of olives, separate the oil from all the fiber and pulp. And there you have it, 100% fat. We all have heard about the good fats in olive oil. Monounsaturated fats, those that have little or no effect on cholesterol. But there´s something you probably don´t know. Olive oil is around 13% saturated fat. That´s far away from being considered just traces. And for someone with heart problems, cholesterol or diabetes that´s a big deal. This is why experienced doctors in those fields recommend to stay away from it.

Same goes for all other oils. And don´t get me wrong, the problem here is not the fat itself. The problem here is that you have a very concentrated product. Actually, highly concentrated. Let´s think about it:

To make one tablespoon of olive oil you would need between 20 to 40 olives (depending on type and ripeness). Let´s say that you use one tablespoon of oil in your salad and one more to sautée some cauliflower and rice, that´s lunch. Now you use another tablespoon in your dinner salad plus you also sautée some green beans. That´s four tablespoon of olive oil in total. That´s 80 to 160 olives in one day. And that without counting all the added oils in the packaged foods you might also eat that day… like maybe a tomato sauce? Or maybe some oil-packed tomatoes on top of your bread? Or some potato chips? Yes, I think you got the count.

Now let´s think about nuts for example. Everybody knows that nuts are very healthy but that you should eat them in moderation. Why? Easy. They are high in fat and calories. If you ask anyone how many nuts a day you should eat, they would probably tell you not more than a small handful. That´s arround 5-8 nuts, depending on the size. Nobody would eat 80-160 olives a day. But actually we are “pouring” them into our food.

Ok, so we got it. Oils, too concentrated. Too much fat all in once. But…what´s actually the real damage?

Well, there are three important reasons to keep them to a minimum or avoid them all together.

  • Excess omega 6.
  • Damage of the arteries.
  • Diabetes.

Let´s start with the first one:

 

Excess omega 6
Most oils have a high ratio of omega 6 versus omega 3. Omega 6 are the pro-inflammatory essential fatty acids while omega 3 are the anti-inflammatory essential fatty acids. They are called “essential” because you need them in your diet. Your body doesn´t produce them, therefore they should come from the food you eat. They are both just as important. When you hit you knee, inflammation is part of the protection/defence mechanism of the body. Omega 3 will compensate too much inflammation.

But how much do we need? In fact, very little. The body´s need for these essential fats are between 2-3% of your daily calories intake. If you exceed this amount, your body could stay in an inflammation state without actually a good reason for it. Furthermore Omega 6 fatty acids can increase blood pressure, thrombosis, vasospasm, inflammatory and autoimmune diseases and allergic reactions to name some; omega 3 fatty acids have the opposite effects.

Though we need both, we don’t want the omega 6 fatty acids get too high versus our omega 3. So, what´s a healthy ratio? A recommended ratio would be something around 4:1 (omega 6 to omega 3). It´s very common that conventional diets are very high in omega 6, usually 15-1 to 20-1 and sometimes as high as 100:1. You might be wondering how that is possible. The reason is that most of the oils used for packaged foods and for cooking are high in omega 6. Oils such as sunflower, corn, grapeseed, safflower and sesame oil are the most common depending on the country.

Another reason why a high intake of omega 6 could be harmful is because they compete with omega 3 for enzymes in order to complete their final product. So an excess of omega 6 could compromise the activity of the omega 3, and this can harm your health and cause disease.

A prevention study of cardiovascular disease found out that:

  • “A ratio of 4/1 was associated with a 70% decrease in total mortality.”
  • “A ratio of 2.5/1 reduced rectal cell proliferation in patients with colorectal cancer.”
  • “The lower omega-6/omega-3 ratio in women with breast cancer was associated with decreased risk.”
  • “A ratio of 2-3/1 suppressed inflammation in patients with rheumatoid arthritis, and a ratio of 5/1 had a beneficial effect on patients with asthma, whereas a ratio of 10/1 had adverse consequences.”
  • “A lower ratio of omega-6/omega-3 fatty acids is more desirable in reducing the risk of many of the chronic diseases of high prevalence in Western societies “

(Source: http://www.ncbi.nlm.nih.gov/pubmed/12442909)

So how can you get enough omega 3 while avoiding excess of omega 6? Here are some tips:

  1. Increase the amount of omega 3 in your diet eating green leafy greens, flaxseeds, hempseeds, chia seeds and walnuts. But be aware you need a small amount, so don´t over do them.
  2. Avoid high omega 6 oils: sunflower, corn, grapeseed, safflower and sesame oil.
  3. Beans, vegetables and fruits are very low in fat overall, but the traces they do contain are relatively rich in good fats- that is, alpha-linoleic acid. This is the basic omega-3 fat that your body uses to produce other good fats.( 1)

 

two bottles of olive oil

 

Now, let´s move on and talk about why they are not good for your arteries.

Damage of the arteries
Monounsaturated oils (such as olive oil) are considered to be “heart healthy”. But that´s far from the truth. They are not “heart healthy”. In olive oil, between 13 to 17 percent of its fats are saturated. It is artery clogging fat just as agressive as fat in meat. And that´s the thing. Saturated fat is saturated fat, no matter where it comes from.

Medical literature is filled with evidence of the harmful effects of monounsaturated oil. Dr. David H. Blanknhorn of the University of Southern California School of Medicine compared baseline angiograms with one-year follow-up angiograms in persons with coronary artery disease. He found that the disease had progressed just as much in those consuming monounsaturared fats as it had in those eating saturated fat.(2)

Foods high in fat, oils and caffeinated coffee damage our endothelial cells. Robert Vogel, the University of Maryland School of Medicine researcher, found that eating bread dipped in olive oil reduces the dilatation in the brachial (forearm) artery.(3) This suggested temporary injury to the endothelial cell, compromising their ability to produce nitric oxide.

Serial angiograms of people’s heart arteries show that all three types of fat—saturated (animal) fat, monounsaturated (olive oil), and polyunsaturated (omega-3 and -6 oils)—were associated with significant increases in new atherosclerotic lesions over one year of study.(4) Only by decreasing the entire fat intake, including poly- and monounsaturated-oils, did the lesions stop growing.

One of the most important clotting factors predicting the risk of a heart attack is an elevated factor VII. All five fats tested—canola oil, olive oil, sunflower oil, palm oil, and butter—showed similar increases in triglycerides and clotting factor VII.(5)

You can have heart disease and still have no symptoms: Blockages of 10-70% have no symptoms but are very unstable and dangerous. You might be exercising, have good cholesterol numbers and a healthy weight…and still have heart disease without even knowing it. According to the PDAY Study it all starts in adolescence: Atherosclerosis begins in youth. Fatty streaks and clinically significant raised lesions increase rapidly in prevalence and extent during the 15- to 34-year age span. Primary prevention of atherosclerosis, as contrasted with primary prevention of clinically manifest atherosclerotic disease, must begin in childhood or adolescence. 100% of the autopsies done on 15-34 year old accident victims showed fatty streaks in the aorta and 50-75% showed streaks in the coronary artery–all precursors to later coronary artery disease. (Sources: http://www.ncbi.nlm.nih.gov/pubmed/8364013 and http://www.ncbi.nlm.nih.gov/pubmed/10052443)

On the contrary, eliminating animal fats reduces the viscosity of the blood, meaning, the blood becomes more fluid making it easy to flow through the arteries and therefore causing a drop on blood pressure. The potassium content in fruits and vegetables also heps reduce blood pressure and other characteristics of plant foods increase this benefit.

(Source: S. Berkow and N.D. Barnard, “Blood Pressure Regulation and Vegetarian Diets,” Nutrition Reviews 63 (2005): 1-8.)

In 1990, Dean Ornish, MD (a Harvard trained physician) tested a low-fat, vegetarian diet in patients with heart disease. Certain lifestyle changes were added too such as exercise, stress control and smoking cesation. Each patient had an angiogram (special x-ray of the heart) before starting the program and another one after a year on it. Both were compared. The results made medical history. The coronary arteries of 82 of those patients (which were previously blocked) were opening again. No drugs, surgery or cholesterol-lowering medications were used.

(Sources: D. Ornish et al., “Can Lyfestyle Changes Reverse Coronary Heart Disease?” Lancet 336 (1990): 129-33. and D.Ornish et al., “Intensive Lifestyle Changes for Reversal of Coronary Heart Disease,” Journal of the American Medical Association 280 (1998): 2001-7.)

Dr. Caldwell Esselstyn, also published his results of patients who had had an average of three previous cardiac events before he put them on a plant-based diet with no added fat – no oil either – and not one patient ever had another cardiac event in twelve years. (6)

 

Diabetes

And finally…what is its relationship with diabetes? Why are people with diabetes recommended to follow a low fat plant-based diet?

High-fat foods increase insulin resistance. Following a low-fat diet will improve insulin’s sensitivity, reduce blood sugar, aid weight loss, and lower your cholesterol.

But wait…I thought sugar was the cause of diabetes! Well, that assumption is inacurate. But that´s another long post. If you are interested in the relationship between fat and diabetes and the reason why sugar is not the evil here, don´t worry, I´ll be writing a post about that soon.

So, what is the real “heart healthy” diet? That is a diet compose of fruit, vegetables, whole grains, legumes and small amounts of nuts and seeds. And that´s the diet many doctors around the world are giving to their patients to prevent and reverse many diseases, but most important ones: obesity, coronary heart disease, cancers and diabetes.

Well, I hope this post gave you a first inside-out about oils and the reasons why it´s smart to keep them to a minimum or avoid them all over. But keep one thing in mind. The important thing is not only to avoid oils, but to keep fats in general low.

 

References:

(1) Dr. Neal Barnard´s Program for Reversing Diabetes by Neal D. Barnard, MD.

(2) D.H.Blankenhorn,R.Johnson. : “The Influence of Diet on the Appearance of New Lesions in Human Coronary Arteries.” Journal of the American Medical Association, March 23,1990

(3) R.Vogel, M. Corretti, and G. Plotnick, “The Postprandial Effect of Components of the Mediterranean Diet on Endothelial Function”. Journal of the American College of Cardiology, 2000.

(4) D.H.Blankenhorn,R.Johnson. : “The Influence of Diet on the Appearance of New Lesions in Human Coronary Arteries.” Journal of the American Medical Association, March 23,1990

(5) Larsen LF, Bladbjerg EM, Jespersen J, Marckmann P. Effects of dietary fat quality and quantity on postprandial activation of blood coagulation factor VII. Arterioscler Thromb Vasc Biol. 1997 Nov;17(11):2904-9.

(6) Esselstyn CB Jr. Updating a 12-year experience with arrest and reversal therapy for coronary heart disease (an overdue requiem for palliative cardiology).Am J Cardiology. 1999 Aug, 84(3):Pages 339-341)

Sources:

  • Prevent and Reverse Heart Disease by Caldwell B.Esselstyn, Jr., M.D.
  • Dr. Neal Barnard´s Program for Reversing Diabetes by Neal D. Barnard, MD.
  • The Starch Solution by John A. McDougall, M.D.  www.drmcdougall.com/misc/2007nl/aug/oils.htm
  • Website Physicians Commiitte of Responsible Medicine http://www.pcrm.org/health/diabetes-resources/frequently-asked-questions-about-diabetes
  • The New Vegan Health Issue: Omega 6 : Omega 3 Fatty Acid Ratio by Sarah Taylor. http://www.vegsource.com/sarah-taylor/the-new-vegan-health-issue-omega-6-omega-3-fatty-acid-ratio.html
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