What we usually call leguminous plants, peas or beans, is the third largest family of flowering plants, consisting of more than 20 thousand species. Leguminosae is a nutritious staple food in the world. They are low-cost sources of protein, vitamins, complex carbohydrates and fiber [1].

Many people may ignore beans in vegetables. In fact, as an independent vegetable different from leafy vegetables, beans also make a unique contribution to our health.

Internationally, although the three words "beans", "beans" and "beans" can be used interchangeably, their meanings are different. Leguminosae refers to any legume, including its leaves, stems and pods. Beans refer to the edible seeds of leguminous plants, including beans, lentils and peas. For example, pea pods is a bean, and peas in pods are beans. Beans are usually used in agriculture (as feed or fertilizer for crops or livestock), and seeds or beans usually appear on our plates. Various forms of beans (kidney beans, black beans, spotted beans, navy beans, chickpeas, etc. ) is just a kind of pulse.

Leguminous vegetables are rich in:

protein

folic acid

Fiber (insoluble and soluble)

iron

phosphorus (P)

Polyunsaturated fatty acids and monounsaturated fatty acids, including linoleic acid and oleic acid.

Several components in leguminous plants may be beneficial to heart health, including fiber, folic acid and phytochemicals. The content of saturated fatty acids and sodium in raw legumes is low. Fiber in leguminous plants is especially helpful for lowering blood cholesterol (even if the weight has not changed), and it can also prevent blood sugar from rising sharply. Cholesterol and blood sugar are both risk factors for cardiovascular diseases [4].

A meta-analysis of most observational studies found that eating leguminous plants four times a week can reduce the risk of coronary heart disease 14%[4].

1 1 Another meta-analysis of clinical trials studied the effects of pulse on two kinds of cholesterol (high density lipoprotein and low density lipoprotein). The results showed that the intake of beans could reduce fasting total cholesterol by about 7%, low-density lipoprotein (bad) cholesterol by 6% and high-density lipoprotein cholesterol (bad) sterol by 2.6. The author points out that soluble fiber, oligosaccharide (a carbohydrate) and phytochemicals in beans may be the reasons for this effect [5].

A cohort study on beans and heart health followed 9632 men and women without cardiovascular disease in the national health and nutrition examination survey. After the discovery of 19, people who eat beans four or more times a week have a 22% lower risk of heart disease and a lower risk of cardiovascular disease (stroke and heart disease) 1 1%[6].

A meta-analysis of 36 randomized controlled trials involving 1 803 participants found that replacing red meat with vegetable proteins such as beans can reduce the risk factors of cardiovascular diseases (cholesterol, triglycerides, blood pressure) [7].

According to animal and cell studies, the fiber, phytochemical composition and mineral content of leguminous plants may have anti-cancer effects. For example, nutrients in leguminous plants, such as zinc, are related to improving immune function and reducing oxidative stress in cells. Selenium and phytic acid have been found to inhibit tumor growth in mice. However, there is no conclusive evidence about human studies on beans and cancer prevention.

Nevertheless, because beans as a high-fiber diet can reduce the risk of some cancers (such as colorectal cancer), the World Cancer Research Foundation (WCRF) and the American Cancer Institute put forward a public health goal in the report "Food, Nutrition and Cancer Prevention: A Global Perspective", that is, adding beans to most diets to help them achieve the goal of eating at least 30 grams of dietary fiber every day. However, the World Cancer Research Foundation specifically pointed out that "foods containing dietary fiber can reduce the risk of colorectal cancer", which indicates that there may be other ingredients in high-fiber foods that will affect the development of cancer, such as promoting the production of a short-chain fatty acid called butyric acid, which is very important for the health of our intestinal flora.

Leguminous plants contain fiber, resistant starch and indigestible carbohydrates, such as oligosaccharides. Resistant starch, sometimes called slowly digestible starch, will not be digested by gastrointestinal tract. After entering the colon, it acts like fiber, promotes the formation of feces, and serves as probiotic food for beneficial bacteria such as Bifidobacterium [9]. When these bacteria decompose and produce anti-fermentation starch and oligosaccharides, they will produce gas, which will lead to bloating and abdominal cramps in some people. Soaking dried beans for at least three hours and then cooking may help reduce this side effect. But in the long run, these beneficial bacteria support normal intestinal function and may reduce the level of carcinogens [9]. During fermentation, bacteria also produce a short-chain fatty acid called butyrate, which may be related to the prevention of colorectal cancer [10].

Leguminous plants have low glycemic index, high fiber content and slow digestion resistance, which may be helpful to prevent diabetes. Despite these beneficial ingredients, the research results are complicated, and there is no clear answer that beans can help prevent type 2 diabetes or lower blood sugar. A limited number of small randomized controlled trials did not produce consistent beneficial conclusions, and large-scale cohort studies were inconclusive. [ 1 1]

A cohort study of 35,988 elderly women in the United States who did not have diabetes at the baseline found that after 6 years of follow-up, there was no obvious correlation between bean intake and diabetes risk compared with those who ate the most beans and those who ate the least.

Another cohort study of 64,277 middle-aged women in China who did not have diabetes at baseline found that after 4.5 years, the risk of developing type 2 diabetes decreased by 38% compared with those who ate beans the most (about 40 grams per day) and the least. [12] It is worth noting that in this study, leguminous plants include soybeans and peanuts in addition to beans, which were not included in previous American studies.

Beans contain dietary ingredients that help to lose weight. Their protein and soluble/insoluble fiber content can increase satiety and moderately increase calorie consumption through heat production. In this process, only about 40% fiber in food is decomposed, thus reducing the total calorie intake. Fiber takes longer to chew, which will slow down a person's eating speed and stomach digestion speed, both of which may lead to satiety.

A study based on the data of 8229 adults from the National Health and Nutrition Inspection Bureau found that people who eat beans are lighter and have smaller waistlines than those who don't. People who eat beans have an increased waist circumference and a reduced risk of obesity by 23% and 22%, respectively.

References:

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