Do Avocados Lower Cholesterol?

Written by Dr. Steve Chaney on . Posted in current health articles, Food and Health, Healthy Living

Should Avocados Be On The Super Fruits List?

Author: Dr. Stephen Chaney

 

super fruits listYou may have seen the recent headlines suggesting that avocados lower cholesterol, are a miracle fruit, and reduce your risk of heart disease. Some of those articles are suggesting that you try to eat an avocado every day. Are those headlines true? Should you be eating more avocados?

If you are like me that would be a bit of a stretch. I prefer my fruits tastier and a bit less greasy, but I won’t let my personal preferences color my analysis of the data. Let’s start by looking at the rationale for testing the effect of avocados on cholesterol levels.

The 2013 American Heart Association Guidelines on Lifestyle Management to Reduce Cardiovascular Risk recommends reducing saturated fats to no more than 5% to 6% of total calories (In the typical American diet about 13% of calories come from saturated fat). The AHA recommends replacing the saturated fat with either monounsaturated fat or polyunsaturated fat (vegetable oils and fish oil).

In addition, a major clinical study has recently shown that a Mediterranean diet supplemented with either olive oil or mixed nuts (walnuts, hazelnuts and almonds) lowers cholesterol and reduces the incidence of major cardiovascular events by ~30% over 5 years in men and women aged 50 to 80 who were at high risk for cardiovascular disease (Estruch et al, N Engl J Med, 368: 1279-1290, 2013).

One avocado has about the same amount of oleic acid (a monounsaturated fat) as 2 tablespoons of olive oil or 1.5 ounces of almonds, so it is logical to suspect that avocados might have a similar effect as olive oil or nuts.

How Was The Clinical Study Designed?

Because there is still a lot of controversy as to whether diets in which the saturated fat is replaced with healthier fat or no fat at all (low fat diets) are better, this study (Wang et al, J Am Heart Assoc, 2015;4: e001355 doi:10.1161/JAHA.114.001355) compared 3 diets:

  • A low fat diet in which most of the saturated fat was replaced with carbohydrate (24% total fat, 7% saturated fat, 11% monounsaturated fat, 6% polyunsaturated fat, 59% carbohydrate, 16-17% protein).
  • A moderate fat diet in which most of the saturated fat was replaced with pure oleic acid (34% total fat, 6% saturated fat, 17% monounsaturated fat from oleic acid, 9% polyunsaturated fat , 49% carbohydrate, 16-17% protein).
  • A moderate fat diet in which most of the saturated fat was replaced with avocado (34% total fat, 6% saturated fat, 17% monounsaturated fat from avocado, 9% polyunsaturated fat , 49% carbohydrate, 16-17% protein).

The study subjects were 45 healthy overweight or obese men and women (age 21 to 70, average = 45). Each subject was put on all 3 diets sequentially for 5 weeks each in a random order. That way each subject served as his or her own control.

The diets were carefully controlled to keep the calories the same so that none of the subjects lost weight during the study (weight loss would have confounded the results because weight loss lowers cholesterol in most individuals). The subjects were also told not to change their exercise habits. In short, it was a small study, but it was very well designed.

When the low fat diet was compared to the moderate (healthy) fat diets, the results were pretty similar to a number of other studies:

  • Total cholesterol and LDL cholesterol (the bad type) were lowered to about the same extent by both types of diets.
  • Triglycerides were higher and HDL cholesterol (the good type) was lower for the low fat diet compared to the moderate (healthy) fat diets.

Because this has been shown in previous studies, I won’t discuss it further here.

Do Avocados Lower Cholesterol?

lower cholesterolWhen the authors compared the diet in which saturated fat was replaced with avocados to the diet in which saturated fat was replaced with oleic acid there were a number of significant differences.

  • Both LDL-cholesterol and non-HDL cholesterol were significantly lower on the avocado diet than the oleic acid diet. The decrease was about 10%. Based on the metrics adopted by the American Heart Association this has the potential to translate into a 20% decrease in heart disease risk.
  • The avocado diet was the only one of the three diets that significantly decreased LDL particle number, small dense LDL cholesterol and LDL/HDL ratio, Many experts think that these parameters are better indicators of hearts disease risk than LDL cholesterol levels.

Do avocados lower cholesterol?  The short answer is yes, eating an avocado a day can lower cholesterol levels and might possibly lower heart disease risk. But to understand the true implications of this study we need to dig a little deeper.

What Is the Significance of This Study?

This study has one important take home lesson and raises two important questions.

Take Home Lesson: Foods Are More Important Than Fats We often hear about the benefits of including more monounsaturated fats in our diet, but when you actually make a direct comparison, such as was done in this study, it turns out that it is the foods that contain monounsaturated fats that make the difference, not the monounsaturated fats themselves. The oleic acid diet was only marginally better than the low fat diet at lowering total and LDL cholesterol.

This was the major conclusion of the authors of the study. Everything else was made up by the non-experts who write the articles that you see in the papers and on the internet. It is yet one more example of the headlines getting ahead of the science.

The authors admitted that we have no idea why avocados are more effective at lowering cholesterol than an equivalent amount of oleic acid. They speculated that it could be due to the high content of phytosterols in avocados. However, while the 114 mg of plant sterols in an avocado makes it an excellent source of plant sterols, it is far below the 2,000 mg of plant sterols that the NIH considers optimal for lowering cholesterol levels.

The authors also mentioned soluble fiber and specialized sugars in an avocado, but none of those was present in sufficient quantities to explain the cholesterol-lowering effect of avocados by itself. It is likely that all of those constituents plus others that we have not yet identified are what make avocados more effective than oleic acid at lowering cholesterol.

Question 1: Do We Really Want To Eat An Avocado a Day?

We need to keep in mind that a single avocado weighs in at around 234 calories. That is:

  • 2.5 times the calories in an apple
  • 4.7 times the calories in a peach or a cup of strawberries
  • 5.7 times the calories in a half cup of blueberries
  • 7.3 times the calories in a half cup of raspberries or blackberries

You get the point. What made this study so effective is that all three diets were designed to provide exactly the same number of calories so that nobody gained or lost weight. If you are thinking of adding an avocado a day to your diet, you are going to need to significantly cut back on calories somewhere else, or your weight gain will drive your cholesterol levels in the wrong direction.

Question 2: What Are The Long Term Implications of This Study?

The bottom line is that this and previous studies suggest that avocados should rightfully be included along with olive oil and nuts as healthy sources of monounsaturated fats that can help you lower cholesterol levels and may reduce your risk of heart disease.

However, we need to keep in mind that while a major clinical study has shown that adding either olive oil or nuts to your diet can reduce heart disease risk, we don’t have a comparable study showing that adding avocados to your diet will have the same benefit. It is plausible, but has not yet been demonstrated.

 

The Bottom Line

  • A recent clinical study has shown that eating an avocado a day was more effective at lowering bad cholesterol than adding an equivalent amount of the monounsaturated fat oleic acid to the diet. This suggests that it is the foods that contain the monounsaturated fats that make the difference, not the monounsaturated fats themselves.
  • This and previous studies suggest that avocados should rightfully be included along with olive oil and nuts as healthy sources of monounsaturated fats that can help you lower cholesterol levels and may reduce your risk of heart disease.
  • However, we need to keep in mind that while a major clinical study has shown that adding either olive oil or nuts to your diet can reduce heart disease risk, we don’t have a comparable study showing that adding avocados to your diet will have the same benefit. It is plausible, but has not yet been demonstrated.
  • You also need to keep in mind that a single avocado contains 234 calories. What made this study work so well is that each diet was carefully designed to provide exactly the same number of calories. If you are thinking of adding an avocado a day to your diet, you are going to need to significantly cut back on calories somewhere else, or your weight gain will drive your cholesterol levels in the wrong direction.
  • Finally, the American Heart Association Guidelines are to reduce saturated fats to no more than 6-7% of total calories. So while the low-carbohydrate, butter, bacon, and steak diet may give you temporary weight loss, it is definitely NOT recommended if you want to reduce your risk of heart disease. For more on this important topic, see my previous health tip “Are Saturated Fats Good For You?

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

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Comments (4)

  • Merlena Cushing

    |

    Good article…helpful, as usual. Please tell me if I needed to sign up again for these weekly updates. Nothing came through today – even checked my SPAM filter – so I came to your site and VIOLA! Here is today’s article.

    Thanks for letting me know if I need to do sign up again.

    Reply

  • Sheri

    |

    Hi, thanks for that important info. 2 ?? I heard that beef from cows that are grass fed & not given growth hormones etc don’t have healthier saturated fat than those that are not. I take a flax seed supplement because I read that in addition to omega 3 fats it also has omega 6 & 9 both said to be beneficial. are there studies on that? Thanks Sheri

    Reply

    • Dr. Steve Chaney

      |

      Dear Sheri,

      Those are very interesting questions and illustrate the incorrect information that abounds on the internet. It may be true that the saturated fat in grass fed beef is no healthier than corn fed beef, but the levels of omega-3 fatty acids are significantly higher so grass fed beef is a bit better for you.

      As for flax seeds, they are a healthy food, but they are no miracle food. Let’s look at each of the fatty acids in flax seed supplements individually. The American diet is generally deficient in omega-3s so they are an important component of the supplement. Unfortunately, the omega-3s in flax seed are short chain, most of the health benefits are from the long chain omega-3s, and conversion of short chain omega-3s to long chain omega-3s in the body is only around 10%. Fish oil supplements are a much better source of omega-3s because they provide predominantly long chain. In contrast, Americans generally get plenty of omega-6 fatty acids. They are found in seeds and most vegetable oils. Omega-9s are the monounsaturated fatty acids. They are found in avocados, nuts, nut oils, nut butters and olive oil. Our bodies can also make them from saturated fats. We get lots of them from our diet. A little more wouldn’t hurt, but the amount we get from a flax seed supplement is fairly insignificant compared to what we already get from our diet.

      Dr. Chaney

      Reply

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Latest Article

Emergency Treatment For Calf Cramps

Posted October 17, 2017 by Dr. Steve Chaney

To Stretch or Not To Stretch

Author: Julie Donnelly, LMT – The Pain Relief Expert

Editor: Dr. Steve Chaney

 

calf crampsA calf cramp is caused by several different conditions, such as dehydration and mineral deficiency.  These each need to be addressed to prevent future calf cramps, but when your calf spasms wake you with a jolt at night or send you crashing to the ground in agony, you need a solution NOW!

And, stretching is definitely NOT the first thing to do.

 

Emergency Treatment for Calf Cramps

A muscle always contracts 100% before releasing.  Once started, a calf cramp will not partially contract and then reverse because you stretch, as it may cause the muscle fibers to tear, which will cause pain to be felt for days afterward.

As a result, it is most beneficial to help your muscle complete the painful contraction before you try to stretch it.  It sounds counter-intuitive, but it cuts the time of the calf cramp down, and enables you to start flushing out the toxins that formed during the sudden spasm.

Your muscle will be all knotted up, screaming in pain, so it’s good to practice this self-treatment when you are not having a calf cramp.

Grab your calf muscles as shown in this picture.  Hold it tightly, and then as hard as you can, push your two hands together.

The intention is to help the muscle complete the contraction as quickly as possible.  During an actual calf cramp it won’t be as “neat” as the picture shows, but anything you can do to shorten the muscle fibers will hasten the completion of the spasm.

Follow These Steps To Release Your Calf Cramps

  • Hold your hands and continue pushing the muscle together until you can begin to breathe normally again.  Continue holding it another 30 seconds, bringing in as much oxygen as possible with slow, deep, breathing.
  • Release your hands and keep breathing deeply.
  • Repeat #1.  This time it won’t hurt, but you are helping any last muscle fibers to complete the contraction before you move to release the spasm.
  • Begin to squeeze your entire calf as if you were squeezing water out of a thick towel.  Move from the top of your calf and go down toward your ankle.  This will feel good, so do it for as long as you can.
  • It is now safe to stretch your calf muscle because the cramp has completed and you have flushed out the toxins.  Stretch slowly, and don’t go past the point of “feels so good”.  You don’t want to overstretch.

This calf cramps emergency treatment has been proven successful by endurance athletes who have written to me saying how they could continue their race (or training) without any further pain.

This is a very important tip to share with all athletes.  Please tell your friends on Facebook and Twitter, it helps athletes prevent injury and pain.

 

Wishing you well,

Julie Donnelly

 

These statements have not been evaluated by the Food and Drug Administration. This information is not intended to diagnose, treat, cure or prevent any disease.

 

About The Author

Julie DonnellyJulie Donnelly is a Deep Muscle Massage Therapist with 20 years of experience specializing in the treatment of chronic joint pain and sports injuries. She has worked extensively with elite athletes and patients who have been unsuccessful at finding relief through the more conventional therapies.

She has been widely published, both on – and off – line, in magazines, newsletters, and newspapers around the country. She is also often chosen to speak at national conventions, medical schools, and health facilities nationwide.

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