4 minutes reading time (775 words)

Classic Tale of the African Green Monkeys

African Green Monkey Portrait

Many people love the classics. Swiss Family Robinson. Jane Eyre. Or even Good Night Moon. All genres have their classics. These stories often owe their appeal to an artful exploration of some truth regarding the human condition. There truly is "no place like home;" a family really can survive by pulling together and using their wits; we believe that intellectual independence is compatible with true love, and that simplicity and familiarity can comfort us to sleep at the end of each day. We enjoy repeating timeless truths because they remind us of where we've been and give us insight for where we're going. Did you know that science has beloved classics, too? One of my favorite (tragedies) is a research study that I call "The Tale of the African Green Monkeys."

African Green Monkeys were introduced into the Caribbean during the years of the slave trade. The monkeys flourished and large, roving bands of them became local pests, destroying farm crops and earning themselves a spot on native menus. Eventually, the monkeys came to the attention not only of local hunters, but also of biomedical researchers. Because African Green Monkeys metabolize fat in much the same way as do humans, Dr. Lawrence Rudel of North Carolina's Wake Forest University Baptist Medical Center used monkeys captured from St. Kitts for a study on the effects of fatty acids on heart health.

Rudel divided the monkeys into three groups, feeding each group an identical cholesterol-rich diet, mimicking the average American diet. There was only one important difference in the food of the three groups: each group's diet was high in a particular type of fat. At that time -- in the 1980s -- the public was being nudged toward using monounsaturated fats to replace saturated fats in their diet. However, no research had established that monounsaturated fats were in fact better for heart health. Rudel set out to discover the truth about saturated fat, polyunsaturated fat, and monounsaturated fat. He used palm oil, oleic acid-enriched safflower oil, and safflower oil, respectively. How did they each affect blood cholesterol levels? Did they equally cause coronary plaque buildup? 

After five years, Rudel found that all three groups of monkeys had elevated LDL cholesterol levels. However, the monkeys who had been eating a diet high in monounsaturated fat showed higher levels of HDL (healthy) cholesterol and lower levels of LDL (lousy) cholesterol when compared to the other groups. Ah-ha! Maybe it was true that monounsaturated fats were better for cardiovascular health? Would these favorable cholesterol readings correspond to cleaner, healthier coronary arteries? Like many good stories, the story of the African Green Monkeys takes an unexpected twist . . .

When Rudel autopsied the monkeys (hence the tragedy), these animals with the higher levels of "good" cholesterol and lower levels of "bad" cholesterol had developed the very same amount of plaque build up in their coronary arteries as the monkeys eating saturated fat! The monounsaturated fat hadn't protected the monkeys from heart disease at all. The "good" results on their cholesterol tests hadn't accurately predicted the condition of their arteries. The monkeys were in fact quite ill with cardiovascular disease despite having high HDL levels.

It's not just classic fairy tales that have morals. This story has a moral as well: Monounsaturated fats and saturated fats cause the same amount of cardiovascular disease. Did you know that olive oil is another oil high in monounsaturated fats? Olive oil is not a "heart healthy" oil.

Oh. In case you'd like to read the sequel to the "Tale of the African Green Monkeys," Dr. Rudel also authored another study with a similar sad ending. I call it "Monounsaturated Love: The Tragic Story of a Rat Romance."

For additional information:

(1) Is Olive Oil Really "Heart Healthy?"

(2) Olive Oil Not Heart Healthy

(3) Sharp Cholesterol Crystals Cut - Causing Casualties!

(4) The Mediterranean Diet: A Closer Look

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Comments (9)

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I would love to see a similar study using the same amount of calories from avocado vs saturated fat, since the avocado has slightly more saturated fat than olive oil and most of the remaining fat is monounsaturated.

  Chris Dove
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If you were to compare avocado oil vs olive oil, you would not see much difference with regards to heart health or overall health. However, avocado being a whole food, packed with micronutrients and a decent amount of fiber compared to olive oil would be no contest. This, however, isn't based on any studies, but just my understanding of how things work.

  Marky Yvanovich
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Fat quantity in a meal matters more than which type of oil. With fat, less is more to the extent that we consume plenty even with just the small amounts in all whole plant foods.

https://www.ncbi.nlm.nih.gov/pubmed/9409274

  Deborah
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This study only compares fat from extracted oil, which we know is bad. What it doesn’t compare is fat from whole food sources like nuts, seeds, avocados, etc. That is basically what Chris was hoping to see in a study.

  Comment was last edited about 11 months ago by Marky Yvanovich Marky Yvanovich
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As I said, the primary point is about fat quantity. It is certainly easier to eat way too much fat when adding oil (even a little bit can add a lot of fat) because as we probably all know, only 1 tablespoon of oil adds 14 grams of fat to a meal. That almost doubles the amount of fat we consume in a whole day when we eat our day's calories from low-fat whole plant foods.

So yes, while we are all agreed that eating whole plant foods is better for many reasons, even the high fat whole plant foods are very high in fat. For example, the fat in avocado is 80% of it's calories. (USDA figure) Oil is 100% fat but 80% is still very high considering that most fruits, vegetables, whole grains & legumes average around 10% fat. :-) The amount of fat in nuts varies a bit between varieties but on average, they are also approximately 80% fat.

One of the negatives that oil, avocado & nuts all have in common is that they are all higher in omega 6 fatty acid than omega 3. The following figures are from registered dietitian Jeff Novick.
https://www.drmcdougall.com/forums/viewtopic.php?f=22&;t=6067&start=30

Here are some of them for your convenience. The ratios describe how much...

As I said, the primary point is about fat quantity. It is certainly easier to eat way too much fat when adding oil (even a little bit can add a lot of fat) because as we probably all know, only 1 tablespoon of oil adds 14 grams of fat to a meal. That almost doubles the amount of fat we consume in a whole day when we eat our day's calories from low-fat whole plant foods.

So yes, while we are all agreed that eating whole plant foods is better for many reasons, even the high fat whole plant foods are very high in fat. For example, the fat in avocado is 80% of it's calories. (USDA figure) Oil is 100% fat but 80% is still very high considering that most fruits, vegetables, whole grains & legumes average around 10% fat. :-) The amount of fat in nuts varies a bit between varieties but on average, they are also approximately 80% fat.

One of the negatives that oil, avocado & nuts all have in common is that they are all higher in omega 6 fatty acid than omega 3. The following figures are from registered dietitian Jeff Novick.
https://www.drmcdougall.com/forums/viewtopic.php?f=22&;t=6067&start=30

Here are some of them for your convenience. The ratios describe how much more omega 6 the food has than omega 3.

English Walnuts 4:1
Macadamia 6:1
CA Avocados 15:1
Black Walnuts 16:1 (16 times more omega 6 than 3)
FL Avocados 17:1
Pecans 20:1
Pistachio 37:1
Hazelnut 88:1
Cashews & pumpkin seeds 117:1
Coconut 293:1
Pine Nuts & sunflower seeds 300:1 (300 x more omega 6 than 3)
Brazil Nut 1000:1
Almonds 1800:1

On the other hand, consuming a daily spoonful of ground flax seed and/or a spoonful of chia seed can improve the omega balance in our daily diet.... plus add important trace minerals, fiber & protein to our diet.

Flaxseed 1:3.9 (4 times more omega 3 than 6)
Chia Seed 1:3 (3 times more omega 3 than 6)

As Jeff also explains in his original article at the above link, the more high fat foods we consume, the more saturated fat we consume. Most plant foods only have a little saturated fat but when our goal is to minimize our intake of it, eating even high fat plant foods may be sabotaging that effort.

It is my understanding that these reasons are partly why Dr. Carney recommends a diet of low-fat whole plant foods for people needing to lose excess weight and reverse chronic disease.

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  Deborah
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I'm in 100% agreement with you regarding fat consumption, especially saturated fat. I try to keep my fat calories at around 10% of my total calories.

  Marky Yvanovich
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I understand the oil vs the whole food thing, but I would still like to see a study done on the avocado. It is still alot of mono and saturated fat hitting the bloodstream.

  Chris Dove
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Chris, did you find the numbers I posted above, about avocado, useful?

The studies that have been done on avocado (as far as I know) seem to be largely paid for by the growers, so caution is warranted when the study concludes only positive results.

Of what I have seen, this report makes the most sense to me. Bottom-line: "...avocados are as fattening as margarine, mayonnaise, and oil, if you’re eating the same amount of fat."

https://nutritionfacts.org/video/are-avocados-fattening/

  Deborah
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Thanks Deborah, I am very familiar with the poor fatty acid profiles of avocados and the vast majority of nuts and seeds. And I take the unpopular opinion that avocados aren't the superfood they are credited for. IMO, they give the illusion that they are heart healthy because of the positive lipid panels while a slow coronary pathology is taking place.The difference between 100% fat and 80% fat is still excessive no matter how "good" it is.

  Chris Dove
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