On1October 20181kloc-0/6, the top academic journal Science published a special issue consisting of five articles, aiming at summarizing the research progress of human beings in this field and further discussing the development direction of dietary nutrition and health. ?
In this paper, Professor David S. Ludwig of Harvard Medical School and other three experts in the field of nutrition science published a detailed review on dietary fat and chronic diseases, and summarized the main findings and opinions in the field of dietary fat and chronic diseases, hoping to attract more attention and dialectical thinking.
Figure 1: Summary of development events of high-carbon water and low-fat health initiative (produced by the author)?
For a long time, it is generally believed that carbohydrates are healthier than fat, and the American government is also the earliest advocate of this theory. ?
However, in recent years, there have been more and more studies on the intake ratio of three nutrients (sugar, fat and protein) in the diet, and the controversy about which diet mode is healthier is also growing. ?
For example, Amazon's latest ranking shows that among the top ten best-sellers related to weight loss, four books recommend ketogenic diet (i.e. high fat, low carbon water and moderate protein diet). At the same time, more and more big data analysis shows that high-fat diet is more effective than low-fat diet in losing weight and has superior clinical performance in controlling diabetes. ?
So is it better to eat low-fat and high-carbon water or high-fat and low-carbon water? Let's take a look at it for you:
What is the truth of low-fat and high-carbon water diet?
At present, the carbohydrate-based diet is still the main source of human energy, providing more than 50% of the daily energy needed by the human body. ?
Studies have shown that developing countries with rice and flour as their staple foods have higher carbohydrate intake, while the incidence of chronic diseases such as diabetes, obesity and heart disease is significantly lower than that of western developed countries. However, among immigrants from developing countries to western developed countries, the probability of these chronic diseases in the next two generations is on the rise. Is this the result of a change in diet? Let's take a look at the truth of low-fat and high-carbon water diet:
1. Several important reasons to support eating less fat?
1) Compared with carbohydrates, fat tastes better and is not easy to make people feel full, so it is easier to eat more. However, one gram of fat (9 kcal/g) provides nearly twice as much energy as one gram of carbohydrate or protein (4 kcal/g), which is more likely to lead to fat accumulation and obesity. ?
2) In an article published in Cell Metabolism on 20/08/kloc, a research team of China Academy of Sciences found that only mice fed with a high-fat diet were obese when given 29 different macronutrients (fat, carbohydrate and protein). ?
3) Both human and animal experiments show that high fat intake can induce a large number of inflammation-related factors and increase the potential risk of cancer. ?
4) The study also found that high-fat diet affects human intestinal microorganisms and secretes secondary bile acids with cancer risk. ?
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However, whether the facts are so simple and clear remains to be discussed. Types and quality of carbohydrates (degree of processing, cellulose content, glycemic index, etc.). ) is also an important factor affecting health. ?
2. High-carbon-water-low-fat diet and obesity, diabetes and cardiovascular diseases?
At the same time, studies in the past few decades have also found many benefits of a low-fat diet. Many experiments/meta-analyses in history have supported that a low-fat diet is good for health. ?
For example, a low-fat diet is beneficial to the regulation of hormones in human body, for example, for women, it is beneficial to prevent breast cancer and intestinal cancer. ?
WHI-DM test and random free eating test also show that although both low-fat and high-carbon diets can lose weight, low-fat diet is better. ?
Another random study of 3234 adults at risk of diabetes found that the intake of low-fat and high-carbon water diet did play a role in reducing the incidence of diabetes. However, a recent meta-analysis shows that it is the rich fiber in high-carbon diet that really plays a role in the prevention and control of diabetes. ?
The relationship between high-fat diet and cardiovascular disease has been debated for more than 40 years. However, a large number of research results can not directly prove the relationship between heart disease and diet. Meta-analysis of two randomized controlled trials shows that low-fat diet can reduce the content of low-density lipoprotein cholesterol (LDL-C), while low-carbon water intake can reduce triglycerides, which has no adverse effect on high-density lipoprotein cholesterol (HDL-C), so a low-fat, grain-based diet is still beneficial to some extent. ?
3. High carbon water and low fat and cancer?
Cancer is the number one killer of human life, and its pathogenesis and types are very complicated, including 100 disease types and subtypes, so it is impossible to comprehensively evaluate the impact of diet. However, there are still several major experiments that provide evidence of the relationship between dietary fat and cancer. ?
WHI-DM study found that the overall incidence of breast cancer in the low-fat diet group did not change significantly. However, after 8. 1 year follow-up, it was found that the incidence of special er-positive and PR-negative breast cancer decreased by 36%. ?
In another study with a follow-up time of 10 year, the researchers found that the low-fat and high-carbon water diet had no significant effect on the incidence of invasive breast cancer. However, in the female nutrition intervention study, the risk of cancer recurrence of breast cancer patients assigned to the low-fat diet group was reduced by 24% within five years. ?
However, a prostate cancer prevention test found that omega-3 fatty acids (N-3) and docosahexaenoic acid (DHA) contained in popular nutritional supplements fish oil may be related to the increased risk of prostate cancer. ?
This finding is strikingly similar to previous studies, which found that a diet rich in N-3 fatty α -linolenic acid would lead to an increase in PSA. Although there is no clear evidence to prove the clinical significance of this special fat for cancer, more research is needed. ?
What is the truth of low-carbon water and high-fat diet?
Restricting carbohydrate diet mainly refers to reducing the proportion of carbohydrate in diet and increasing the proportion of fat (≥40%). Emerging research evidence shows that ketogenic diet, as a special type of low-carbohydrate diet, usually accounts for more than 70% of fat, which may have a unique therapeutic effect compared with other traditional diets. ?
Fig. 2: The diversified effects of ketogenic diet on human body?
(source: science)?
1, high-fat and low-carbon water and obesity, diabetes and cardiovascular diseases?
The 40-year-old high-carbon and low-fat diet and traditional drug treatment have not played a good role in inhibiting obesity and type 2 diabetes. Today, three-quarters of American adults are overweight or obese. ?
Recent reviews and related meta-analysis found that carbohydrate-restricted diet is actually better than low-fat diet, especially ketogenic diet, for short-term and medium-term weight loss. ?
The study also found that restricting carbohydrate diet has beneficial effects on human metabolism, gene expression, inflammation and oxidative stress. It can even improve some metabolic syndromes, including central obesity, high triglyceride, low HDL-C, hypertension, abnormal glucose tolerance, fatty liver, chronic inflammation and a series of clinical risk factors that easily lead to diabetes and CVD. ?
A two-year experiment found that ketogenic diet can significantly reduce serum triglyceride, increase HDL cholesterol concentration, reduce inflammatory markers and reduce circulating saturated fatty acid concentration. ?
According to a recent survey, 365,438+06 children and adults with type I diabetes have been significantly controlled by low-carbohydrate and high-fat diet intervention for more than two years, with low incidence of complications and good metabolic indicators. ?
In another case, 226 patients with type II diabetes who only took metformin for hypoglycemic therapy received ketogenic diet intervention with remote support. The results showed that the average weight of the population decreased by 12%, and the HbA 1c (glycosylated hemoglobin-a response index of human blood sugar control) decreased by 1.3%. ?
Ketogenic diet is not perfect, for example, low-carbohydrate diet usually contains a lot of saturated fatty acids. It is also necessary to comprehensively consider the increase of LDL-C caused by ketogenic diet (this will happen to about half of the population in ketogenic diet). ?
2. High-fat and low-carbon water and cancer?
Restricting carbohydrate intake can inhibit specific oxidative stress, inflammation and cell signal transduction involving metabolic hormones, thus preventing or treating specific cancers. Well-known applications include the use of ketogenic diets to enhance the effectiveness of PI3K inhibitors in cancer treatment. However, due to the small sample size and lack of high-quality randomized controlled trials, the relationship between cancer and ketogenic diet is still uncertain. ?
Different types of dietary fat and their effects on common chronic diseases?
In addition to the content of fat in the diet, the effects of different types of fat on health have also been controversial. Based on a number of feeding control studies, long-term epidemiological studies and randomized trials, a large number of results prove that the types of dietary fat will also affect human health. ?
1, Fat Types and Obesity and Diabetes?
There are many studies on total fat intake and obesity, but there are few studies on the influence of specific types of fat on weight control. ?
A seven-week diet control study found that the increase of trans fat and saturated fat intake was positively correlated with weight gain, but the intake of monosaturated fatty acids and polyunsaturated fatty acids had no effect on weight. At present, there is no randomized control that lasts more than one year.