Classic Tale of the African Green Monkeys

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