The human body is the most complex machine on Earth. Like any machine, it requires an input of fuel to run along with a variety of chemicals for proper maintenance. In this case, these requirements are met by food. But food is incredibly complex, even a simple meal is made up of hundreds of compounds. It’s crazy to think that simple predictions can be made about what might happen when something as complex as food is introduced into an organism as complex as a living body, especially given that the living bodies in question may differ in genetics , gender, age and health. been However, simple nutritional advice is routinely given!
For example, to reduce the risk of heart disease, we are told to replace saturated fats, such as those found in red meat, dairy products, and tropical oils such as coconut, with unsaturated fats found in in seed oils. Unfortunately, the story is much more complicated. (A quick chemistry lesson here: Saturated fats contain no carbon-carbon double bonds in their molecular structure, while unsaturated fats contain one or more double bonds.)
This discussion was prompted by a study I came across in which researchers in Nigeria determined the fat composition of insects, specifically bees, winged termites, soldier termites, and mopane worms. Since these insects are eaten in some parts of Africa, their nutritional content is interesting. What caught my attention in this report was the following statement: the higher the ratio of polyunsaturated fatty acids (PUFA) to saturated fatty acids (SFA), the more nutritionally useful a dietary oil and the PUFA/SFA ratios in the present study. good enough to discourage the atherosclerotic tendency. Atherosclerosis is the buildup of plaque in the arteries that can lead to cardiovascular disease. The implicit message of this study is that eating insects is heart-healthy.
This study really has no practical relevance to us, as insects are not an option in the Western diet. But portraying polyunsaturated fats as angels and saturated fats as demons is too simplistic. For example, a large study conducted in nine European countries found no strong association between dietary saturated fat and heart disease. Neither did the incidence of heart disease decrease by substituting saturated for unsaturated fats. However, the situation turned out to be different when the sources of saturated fat were considered. Saturated fat from red meat or butter increased the risk of heart disease, but saturated fat from yogurt or cheese reduced it.
The standard advice for years has been to replace saturated fats with unsaturated vegetable fats. This seems justified when we consider the heart-healthy Mediterranean diet in which unsaturated fats come mostly from olives, nuts and fish. But the story is different when saturated fats are replaced with oils from seeds such as soybean, sunflower, cottonseed or corn, as is common in the Western diet. The prominent fatty acid in these oils is linoleic acid (a so-called omega-6 fatty acid due to the presence of a double bond at the sixth carbon from the end of the molecule).
Awkwardly, studies have shown that replacing saturated fats with vegetable oils containing linoleic acid actually increases the risk of heart disease. This is despite the fact that total cholesterol and LDL cholesterol are reduced! This is surprising, since lowering blood cholesterol is generally thought to be desirable. In fact, numerous studies have shown that lowering high cholesterol with the use of drugs such as statins reduces the risk of heart disease, but studies that have focused on lowering cholesterol through diet have been inconclusive. . This may be because statins also have an antioxidant effect that can mitigate the risk of heart disease.
The problem with linoleic acid is its susceptibility to oxygen attack, that is, to being oxidized. When linoleic acid is incorporated into LDL particles, as with fatty acids, it undergoes a reaction with oxygen and breaks down to form oxidation products such as malondialdehyde and 4-hydroxynonenal. When LDL containing these oxidation products is deposited on artery walls to form plaque, it causes inflammation which in turn makes the plaque prone to rupture. When this happens, a blood clot can form, precipitating a heart attack or stroke. Conversely, omega-3 fats, as found in fish, are also polyunsaturated fats, but they are not prone to oxidation, and replacing saturated fats with these appears to be protective.
Now back to the insects. Its fat content is mostly linoleic acid. Therefore, the suggestion that eating insects may reduce the risk of heart disease due to a favorable PUFA/SFA profile is incorrect. If the polyunsaturated fatty acids are mostly linoleic acid, the profile is not favorable.
Obviously, the link between diet and heart disease is frustratingly complex, but labeling polyunsaturated seed oils, which are increasingly found in processed foods, as healthy is wrong. So is labeling all saturated fat as unhealthy. Although they generally raise cholesterol, the extent to which they do so depends on their molecular structure. Those containing 14 or 16 carbon atoms, specifically myristic and palmitic acids, raise cholesterol, while lauric and stearic acids with their 12 and 18 carbon chains are relatively harmless.
To further complicate the picture, saturated fat also increases HDL cholesterol, the so-called good cholesterol. In fact, the best measure of risk is not LDL, but the ratio of total cholesterol to HDL. To insert some practical numbers here, total cholesterol should be less than 5.2 mmol/L and HDL should be more than 1.5 mmol/L, meaning the ratio should ideally be less than 3.5. However, a diet in which saturated fat is replaced with linoleic acid-rich seed oils may decrease this ratio but still increase the risk of heart disease!
If that’s not complicated enough, determining the number of LDL particles in the blood is a better measure of risk than just measuring LDL cholesterol levels. Apolipoprotein B, or ApoB, is a protein found in LDL particles, and the extent of its presence is indicative of the number of LDL particles. Levels above 1.2 grams/L are considered high.
Now let’s try to uncomplicate things. Talking about the total intake of saturated and unsaturated fats makes no sense because fatty acids differ in their effects, and the effects also depend on the food matrix in which they are present. Therefore, it is much more meaningful to talk in terms of foods than specific nutrients. Here it goes. Limit red meat, white flour, sugar, salt, soft drinks and be careful with everything that comes in a box. Use oils such as canola, olive, safflower or avocado that are low in linoleic acid and low in saturated fat. Eat 5-7 servings of fruits and vegetables a day with at least one serving of berries. Cheese and yogurt are fine. Emphasize fish and whole grains. Exercise 30 minutes at least five times a week. Not so complicated. And yes, choose your parents carefully.
@JoeSchwarcz
#Disclosure #dietary #fat
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