Chapter 20 Chapter 18 Animal protein has many benefits

For billions of people in the world, hunger remains the number one problem afflicting their existence in the new millennium.Lack of food means lack of nutrients.Insufficient protein is a typical nutritional deficiency disease in famine areas.Its impact on physical health is enormous, and I won't dwell on it here.The root of the problem lies in the body's inability to convert other nutrients into the protein it needs.For example, the body can also convert carbohydrates into fat, or protein into glucose.However, the human body must constantly take in specific amino acids, so amino acids are indispensable substances for the human body.The most abundant source of amino acids is animal food.An average adult needs at least thirty-five to forty grams of protein per day to obtain all the amino acids the body needs.

In the latest scientific study, we found clear evidence that a lack of the protein leads to dysfunction in the pancreatic islet gland cells.We know that the pancreas is an organ that synthesizes insulin, and insulin secretion is insufficient and its efficacy is not good.If there is a long-term lack of protein, this dysfunction becomes chronic, and even if protein is supplemented, it cannot be recovered.It can be inferred that children with long-term malnutrition are more likely to develop insulin resistance in later years than others, and the probability of developing type 2 diabetes is also relatively increased.This causal relationship may explain why the number of diabetics has soared in recent years as Third World countries urbanize and the caloric supply of food suddenly increases as readily available and cheap carbohydrates and vegetable oils flood the market. .

Those of us who live in advanced industrial countries no longer know the taste of hunger.Even obese people are disproportionately from lower social classes.There is no one around us who does not get enough protein. The average daily intake of German women is nearly 70 grams, and that of men is about 90 grams. The average American intake is about 100 grams per day.In most industrialized countries, the proportion of protein in caloric intake reaches 13%︱17%, and the proportion of animal protein is higher than that of vegetable protein. For a long time, some experts in the field of nutrition believe that such a large intake of protein, especially animal protein, is harmful to health.They even loudly warn that the current high intake is dangerous.A well-known German professional society proposed the first ten principles of health nutrition many years ago, so that German consumers can use this as a reference standard to improve their health.The seventh of them is to eat less animal protein.

Too much protein, especially animal protein, is considered a disease-causing suspect.I couldn't help but ask myself again and again: For whom, or for what, is this too much? How bad is our current intake of protein, especially animal protein, doing us?There are four topics for discussion: first, too much protein has toxic effects; second, too much protein can damage the kidneys; third, too much protein can cause osteoporosis; fourth, protein is saturated with animal Fatty acids and cholesterol are linked together. If there are too many of these things, it will induce heart and circulatory system diseases.

Let me talk about the first point, amino acids are highly active life substances, so people have reason to believe that taking too much will bring relatively adverse side effects.In addition, protein contains nitrogen, which must be excreted by the kidneys as urea, otherwise it will be harmful to the body, and the liver must provide relative enzymes for this.According to theoretical calculations, the maximum limit a man weighing 80 kilograms can bear is 350 grams of protein per day.But in healthy people, the protein's toxic effects have never been demonstrated, only in people who are seriously ill or have a specific medical history.

The second point is about the kidneys.It's an argument that has been touted by nutrition counselors for years, but it's based on speculation and imagination.Here's why: Experts have observed that the blood circulation and filtering function of the kidneys is enhanced after the intake of protein-rich foods.For people who have developed renal dysfunction, their gradually reduced renal units must take over the work of the part that is no longer functioning.In this case, if a large amount of protein is taken in, increasing the working pressure of the kidney will only accelerate its failure, at least people think so.Therefore, this article has become one of the pillars of modern nutrition theory: too much protein damages the kidneys.

A recent meta-analysis looked at the effect of controlling protein intake in patients with kidney disease.As a result, our imaginations have far outstripped reality at this point, and doctors now no longer recommend restricting protein intake in patients with mild renal impairment.For patients with severe kidney disease, it is sometimes beneficial to limit protein, and generally allow them to consume no more than ○.eight grams.This is the same amount recommended for a healthy person. What kind of people will suffer from kidney disease?Diabetics suffer from this rare condition disproportionately.Long-term diabetic patients have high blood sugar concentration for a long time, which will definitely affect kidney function.The national census shows that about 30% of diabetic patients have slightly impaired renal function, and 10% have severely impaired kidney function.But what does this have to do with healthy people?

What about those obese people who are likely to develop insulin resistance sooner or later and suffer from unknown syndromes?Not long ago, a surveillance survey by the University of Copenhagen looked at this question.They found five obese people who were willing to experiment with two different diets for weight loss.Both diets contained less fat, but one contained 25 percent protein and 45 percent carbohydrates, and the other contained 12 percent protein and 58 percent carbohydrates.During the first six months, participants on both diets lost weight, with those eating more protein losing three kilograms more.What about the kidneys?We found that the kidneys of the subjects who ate more protein began to grow, apparently in order to adapt themselves to the increased workload.As a result, their kidney function improved by 10 percent compared to subjects who ate less protein.Experiments found no signs of harm to the kidneys.The alarm can be lifted, as long as you are not a long-term diabetic.As for the idea that protein will cause kidney disease in healthy people, it can be classified as a nutrition fairy tale, or simply thrown into the trash can.

The third point is that it is better to be cautious about the risk of osteoporosis.Under experimental conditions, we have often observed that the loss of calcium in bones is exacerbated by the intake of large amounts of pure protein.Some studies cannot prove this.It is possible that if sufficient calcium is ingested at the same time, intestinal absorption increases to compensate for the loss of calcium.In addition, the increase or decrease of calcium is also related to many other factors, including the supply of phosphate, magnesium, vitamin D, the intake of grains and their phytates, which inhibit mineral absorption, and the amount of exercise.We still don't fully understand this issue.Experts who study osteoporosis have been arguing for a long time, raising one unanswered question after another, but no one can come up with a specific answer.

We can think that under realistic conditions, if you use close to natural raw materials, eat a variety of dietary ingredients, eat more vegetables and dairy products, and ensure that you have an appropriate amount of exercise every day, the possibility of bone calcium deficiency is unlikely.In conclusion, most epidemiological studies have failed to prove that high intake of protein causes osteoporosis.A new long-term observational study even shows that a large intake of protein can reduce the incidence of bone fractures. Fourth, and finally, the danger of heart and circulatory disease.What would happen to our blood sugar, insulin and fat metabolism if we consumed more protein than the current average?For people with insulin resistance and unknown symptoms, in order to reduce carbohydrate intake, it is best to look for relative alternatives.As discussed in Chapter 15, a little more fat has been shown to have beneficial effects.So what if we replaced some carbohydrates with protein?

The extent to which protein causes blood sugar to rise is limited, and the protein in beef and fish causes the lowest extent.But regardless of the blood sugar response, protein raises insulin concentrations to moderate levels in healthy people and even higher levels in diabetics.Why this is so, we don't yet know.The significance and effect of this discovery on health is still unknown, but from the general trend, protein can control blood sugar at a lower level. We have observed in animal experiments that taurine, a protein mainly derived from beef, can improve insulin sensitivity.Monitoring studies in insulin-resistant humans have also shown that a low-calorie, protein-rich (30% to 45%) diet significantly improves insulin sensitivity compared with a carbohydrate-rich diet.Other than that, there is no further understanding of this issue. Under the condition of being able to choose food freely, taking in more protein can also help the initial stage of weight loss.That's because, of all the nutrients, protein quenches hunger the fastest and keeps you feeling less hungry for the longest time.In addition, the metabolism of protein will consume up to 30% of the energy it contains. Therefore, a weight-loss diet with high protein content will prevent the body's basal metabolism from falling so low when hungry.In the long run, whether high protein is an effective weight loss method is another question, and I am more skeptical about it.This has not been proven so far.In my opinion, it is more realistic that, because of the above characteristics, a diet rich in protein will at least help control the weight and not continue to gain. What about fat metabolism?Regarding this issue, Professor Bernard Wolfe of the University of Western Ontario in Canada has conducted breakthrough research in recent years.In multiple closely monitored metabolic studies, he replaced a portion of carbohydrates with calorie-equivalent protein, while keeping the fat ratio constant.The proportion of protein in the diet increased to 22% to 27%, and the relative proportion of carbohydrates decreased to 40%︱45%.He primarily chooses animal protein as his protein source, including lean meat, poultry, less fatty fish, and low-fat dairy.He administered the same diet to women and men with high cholesterol and to healthy subjects. All of his experiments yielded the same result: an increase in protein and a decrease in carbohydrates in the diet resulted in a significant decrease in all important blood fat indices and a rise in HDL cholesterol.Professor Wolf's latest research on subjects with normal blood lipids showed that total cholesterol dropped by 5%, low-density lipoprotein cholesterol dropped by 9%, and triglycerides dropped by 26%. Density lipoprotein triglycerides dropped 35 percent and HDL cholesterol rose 5 percent.The ratio of total cholesterol to HDL cholesterol dropped by 10%, and the ratio of triglycerides to HDL cholesterol even improved by 30%.Seeing such a result, we have nothing to say. Does such a successful result match the data of epidemiological studies?To date, a total of seven human long-term observational studies on the effect of protein intake on the incidence of myocardial infarction have been conducted.One showed that protein increased the risk of disease, but the analysis of this study did not take into account some other important influencing factors.Five studies showed no causal relationship.The Harvard Department of Nutrition recently released the results of the Nurses' Health Survey, the most detailed study to date on this question. They observed 80,000 women over a period of fourteen years, taking into account all conceivable influences and confounds caused by medical and dietary conditions.The results are still clear: a large intake of protein, not only plant protein, but also animal protein can significantly reduce the possibility of myocardial infarction!Women who consumed the most protein, with a moderate protein content of 24% in their diet, had a 26% lower incidence of myocardial infarction than those who consumed less (15%).It made no difference whether their protein-rich diet was high-fat or low-fat.A closer look shows that especially animal protein is associated with a lower incidence of myocardial infarction, because among the protein sources, beef accounts for 20%, which is the largest source of supply, followed by chicken 15%, fish 1%, Low-fat milk 10%, cheese 10%, brown bread 8%, white bread 7%, breakfast cereal 5%. Any more scary news about protein?An impression obtained by experts through epidemiological studies seems to be that consuming large amounts of protein is associated with lower blood pressure.This may explain why, in the largest long-term observational study in Japan, people who ate the most protein, especially through meat and dairy products, had the lowest rates of death from stroke.Finally, I would like to mention a result of the Nurses' Health Survey: Women who developed breast cancer during the survey had a significantly improved chance of survival when they increased their protein intake, especially animal protein. It sounds harsh to everyone who is involved in the field of nutrition. The seventh article of healthy nutrition issued by the German Professional Nutrition Organization in 2000 is still: eat less animal protein.