Weight loss study (VII)
Whenever we talk about low carb diets and protein and fat supplementation, we always hear the question: What about elevated cholesterol? Those who have updated their nutrition knowledge will ask more specifically: What about elevated LDL cholesterol? The topic of cholesterol is quite complex, and it is not easy to make it clear, just thinking about how to write about it gives me a headache, so I just keep avoiding and delaying it. Now that I’ve come to chapter 7, there’s really no room for dodging and retreating, so I’ll just have to write a little bit of the information I’ve collected and organized.
For the record, the topic of cholesterol is a very specialized medical field, far beyond my knowledge and experience. Therefore, unlike the first six chapters, my understanding and explanation in this chapter may have some deviations due to my limited personal ability, so I hope that readers from medical and nutrition professions will give me advice in the comment section and improve the inappropriate or even wrong places in the text through interactive comments.
End of statement.
Whatever your impression of cholesterol is at this moment, you need to know one thing: cholesterol is one of the components of blood lipids and a substance that our body needs. It is involved in more than 300 chemical reactions in our body and is also an important component of the cell membranes that make up our body. Therefore, our entire body needs cholesterol. Especially the brain, which consumes more than 20% of the cholesterol in the whole body. So there is nothing largely wrong with the statement that the brain loves fat. In addition, cholesterol assists in the synthesis of vitamin D, as well as various steroids. Steroids alone contain sex hormones, so it may be true that a long-term vegetarian diet without steroids is good for concentrating on spiritual practice.
The previous sentence is a joke, don’t take it seriously. Cholesterol is extremely useful for the body, and there is a second thing to know about this: cholesterol is so important to the body that our bodies cannot pretend to be someone else’s. The body gets 80% of its cholesterol from the liver and only 20% from food, which is absorbed into the body through the small intestine. In other words, a very small percentage of cholesterol comes from food. What happens when we have too much cholesterol in our food? The body will allow the excess cholesterol to be excreted, rather than entering the bloodstream indefinitely. This balance is controlled by the brain, and if there is not enough cholesterol in the body, then the brain allows the liver to synthesize more. If it is not consumed, it is returned to the liver for breakdown.
So, how much cholesterol you eat is not causally related to how much cholesterol you have in your body. Your body will synthesize it on its own, whether you eat it or not.
But where did this perception come from, when many people believe there is a direct correlation between dietary cholesterol and cardiovascular disease? Back in 1913, the Russian pathologist Nicolai Anitschkow injected pure cholesterol into rabbits in an experiment, after which he found the same damaged lesions in the rabbits’ blood vessels as in human blood vessels. Based on this, the American physiologist Ancle Keys proposed the famous saturated fat causes heart disease hypothesis in 1952. This hypothesis was adopted by WHO and governments and became popular in the following decades.
However, Nicolai’s experiments were conducted on animals such as rabbits and chickens. The problem was that rabbits and chickens were vegetarians and did not eat meat, nor were they in the habit of consuming cholesterol from food. It was not convincing that Nicolafi would inject someone with a tube of cholesterol and then develop a lesion. Anyway, by 1997, Ansell expressed his opinion this way, saying, “There is no correlation between cholesterol in food and cholesterol in the blood, and we’ve always known that. Unless you’re a chicken or a rabbit, there’s nothing wrong with the cholesterol in your blood.”
In Framingham, Massachusetts, a small white middle-class town just 50 miles from Boston, a large epidemiological study extending 72 years has been conducted from 1948 to the present. Because of the collection and preservation of detailed physical data from three generations of residents, much valuable statistical knowledge about lung and cardiovascular disease has been derived. In a 1992 analysis, it was pointed out that the more saturated fat a person eats, the more cholesterol he eats, and the more calories he eats, the lower his serum cholesterol is. Also, the people who ate the most were the healthiest.
A related paper in the American Journal of Epidemiology in 2006 also noted that higher amounts of total serum cholesterol significantly lowered the risk of Parkinson’s disease. The same journal claimed in a 2012 paper that the rise in Alzheimer’s disease was associated with high-carbohydrate foods and its decline was associated with high-saturated-fat foods.
So does that flip the script on cholesterol? Nope. The latest American Association of Cardiovascular Medicine and European Cardiovascular Society guidelines on the subject both state that cholesterol contributes to cardiovascular disease. For its part, the U.S. has even expanded the population for which lipid-lowering statins are indicated, based on cardiovascular disease risk assessment scores, to allow more nationals to use them to reduce the incidence of cardiovascular disease. The American College of Cardiology recommends that all white men over the age of 62, black men over the age of 65, white women over the age of 70, and black women over the age of 69 take a Statin class. Because Statin is so commonly used today, people have even coined the word “vitamin S” to refer to Statin.
What is the reason for this? Why does the mainstream medical opinion still insist that cholesterol causes cardiovascular disease? Because as human research has progressed, it has become clear that cholesterol is a very complex substance and it takes a lot of work to explain it.
As mentioned earlier, cholesterol is a blood lipid. For it to be transported throughout the body, it needs to be combined with proteins to form lipoproteins. If we continue to break it down, it can be divided into high-density lipoprotein cholesterol (HDL), medium-density lipoprotein cholesterol, low-density lipoprotein cholesterol (LDL) and very low-density lipoprotein cholesterol. The HDL cholesterol and LDL cholesterol are the ones we need to focus on. For the sake of memory, you can think of it this way: we usually call people “low” when we say they are despicable and mean, and Low is the English word for low, which is the L at the beginning of LDL; we usually call people “high” when they are drunk and happy. In this way, it is easy to distinguish the two different kinds of lipoprotein cholesterol.
Through research, doctors have found that HDL is good for cardiovascular disease, so they call it “good cholesterol”; the higher the LDL level, the greater the risk of cardiovascular disease, so they call it “bad cholesterol”. This is still a very crude classification, and the researchers went on to find at a more granular level that
Low-density lipoprotein cholesterol (LDL) is not a single species, but a group of tiny particles with different densities. If you break it down further, you’ll find that LDL can be divided into several types, one small and dense and one large and loose. The former can greatly increase the risk of cardiovascular disease, but the risk of cardiovascular disease caused by the latter is unchanged.
Why does small, dense LDL contribute to cardiovascular disease? As research continues, medical doctors are focusing on Apo-B, the structural protein in LDL, and Apolipoprotein B. If Apo-B is oxidized, abnormalities occur. It can be deposited across the blood vessel wall, forming macrophages that try to engulf cholesterol, only to turn into foam cells because of the large amount of fat absorbed, eventually causing lesions in the vessel wall. Therefore, it is the oxidized Apo-B in LDL that causes cardiovascular disease, not the whole LDL.
Let’s stop here for the complicated medical knowledge and return to the consideration of the medical report. Since the problem is Apo-B, it is a bit wrong to check for high and low LDL. Because as said before, LDL is a group of small particles, and it is the small particles that are in trouble now. Looking at the total amount alone, not to say wrong, at least the indicator is not sensitive and accurate enough, right? Therefore, in recent years, some doctors have recommended the use of Apo-B as an auxiliary LDL measurement standard, the higher the value of Apo-B, the higher the risk of cardiovascular disease is. Specifically, your doctor will ask you to measure a ratio: Apo-B/Apo-A1, where Apo-A1 is the structural protein of HDL, which is beneficial for your cardiovascular disease. This ratio is much more sensitive; a larger ratio means you are at greater risk, and a smaller ratio means you are at less risk.
Remember the town of Framingham mentioned earlier? Medical doctors have also done historical data statistics to study the correlation between HDL and LDL. The conclusion is this: if HDL is low, then the risk of cardiovascular disease will spike with a random increase in LDL; but if HDL is high, then the impact on the risk of cardiovascular disease is consistent with how your LDL increases (not that it doesn’t, but that it doesn’t spike). This is one side of the story that proves the value of Apo-B/Apo-A1.
The human body is such a complex system that it would be inappropriate to discuss one indicator alone and then say that its value is associated with cardiovascular disease. It is necessary to correlate some core data and make a judgment from the whole panorama. The mainstream medical community, as mentioned earlier, believes that LDL is associated with cardiovascular disease, but it does not say that this is the only factor. Other factors are blood glucose, blood pressure, acid triglycerides, genetics, exercise, blood flow shear stress, etc.
Medical doctors then studied the association between acid triglycerides and LDL and found that the body’s acid triglycerides varied little in LDL values between the three different states of high and low acid triglycerides, but that the corresponding LDL structures varied greatly. In the case of medium and low acid triglycerides, the LDL structure was similar and the Apo-B values were both low; however, in the case of high acid triglycerides, the Apo-B values became high. In other words, the more acid triglycerides there are in the body, the less safe LDL is.
If the cholesterol number is high, we can say this: don’t be afraid of cholesterol, it is needed by our body; cholesterol intake through food is limited, don’t be afraid of eggs and meat; if the cholesterol number is high, analyze the value of HDL and LDL, the value of HDL is high enough, then LDL is high enough not to worry too much; HDL cannot be raised by taking medicine, it can only be synthesized by the body. If the LDL value is high, then you need to consider whether your blood pressure is normal, whether your blood sugar is normal, whether your acid triglycerides are normal, if all of the above are normal and only LDL is high, then there is no need to worry too much, but if blood pressure is high, blood sugar is high, acid triglycerides are also high, and LDL is also high, then you really need to pay attention. So, if you are high LDL, you need to lose weight and exercise to bring down your blood pressure, blood sugar and acid triglycerides. Instead of doing nothing, just open your mouth and ask: what if I exercise, what if I eat meat, what if I eat eggs and my cholesterol gets high? What if it threatens my heart and brain vessels?
If you really don’t want to do anything, then you can also consider studying the structure of your daily intake of fats and oils. Balancing the ratio of omega-3 to omega-6 fatty acids, working towards a 1:1 ratio and avoiding various vegetable seed oils whenever possible, may be helpful in lowering the fat in your body. But that’s your homework, not mine.
Anyway, bring back the scrambled eggs with butter and let the olive oil with vegetable leaves appear, all glory to the movement!
(to be continued)
Title photo photography by Joshua Hoehne
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