One reason is enough to advise you to eat more apples!

An apple a day keeps the doctor away. I'm sure everyone has heard this health motto, but is there any scientific basis behind it?

Apples don't have a high vitamin A content, nor are they as good for eyesight as carrots. They are not an important source of vitamin C, and they don't help the body fight colds like oranges.

However, apples contain a variety of bioactive substances . These are natural substances that occur in small amounts in food and are not considered nutrients (such as vitamins), but have biological effects on the human body that promote health . For this reason, apples are considered a "functional" food.

How to define functional food

The term "super food" is popular in the West. Capital likes to label foods such as kale, spinach, and blueberries as "super" in order to attract public attention and increase sales.

By definition, superfoods are foods that are high in nutrients and have exceptional nutritional value . For example, salmon and tuna are considered superfoods because they contain omega-3 fatty acids, which are good for heart health.

Advertisements claim that consuming superfoods can improve certain aspects of your health. The problem is that most of these claims are not based on scientific research – which is the fundamental difference between superfoods and functional foods.

Functional foods contain many bioactive substances, each of which plays a unique role in the body. Bioactive substances can be naturally present in food or added during processing.

As research expands, scientists are discovering more and more bioactive ingredients in food. These substances themselves are not new discoveries, but scientific studies have confirmed their health benefits.

Carotenoids are the most prominent class of biologically active substances. They are a group of 850 different pigments that give fruits and vegetables their yellow, orange, red, and other colors. The main function of carotenoids is to act as antioxidants, promoting health by helping to prevent cell damage. Different carotenoids may work in different ways.

Foods rich in carotenoids are typically brightly colored fruits and vegetables, such as colorful bell peppers.

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Beta-carotene is the most well-known carotenoid because it is found in very high concentrations in carrots. When the body consumes beta-carotene, it is converted into vitamin A in the body - essential for maintaining vision.

Lutein and zeaxanthin also provide key vision protection, especially for the elderly. As the name implies, they give fruits and vegetables their yellow color, and foods such as corn and peppers are rich in these yellow carotenoids.

Research suggests that carotenoids and other classes of bioactive compounds found in food may help prevent certain cancers and improve heart health . Notably, fruits and vegetables rich in carotenoids have been linked to a lower risk of cardiovascular disease and certain cancers, but carotenoids in supplement form offer fewer benefits.

Functional food trend

Although the famous saying "Apple Doctor" originated in the 19th century, nutrition is a young discipline, and the concepts of "functional foods" and "bioactive ingredients" are even younger.

From the early 20th century until the 1970s, nutrition research focused on vitamin deficiencies. Officials encouraged the public to eat more processed foods that were "fortified" with vitamins to prevent deficiency diseases such as scurvy, caused by severe vitamin C deficiency, and rickets, caused by long-term vitamin D deficiency.

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However, the practice of emphasizing certain diets to correct nutritional deficiencies often leads people to pay too much attention to certain nutrients and over-consume certain foods. Coupled with the popularity of processed foods, there is a clear trend of weight gain, and the risks of diabetes, high blood pressure, and heart disease will increase.

In 1980, the U.S. government issued its first dietary guidelines, advising residents to eat less fat, sugar and salt. Public health authorities encouraged people to replace high-fat foods with starchy foods such as bread and pasta.

This type of nutritional advice has led to even worse consequences: Obesity and diabetes rates have continued to soar, and there is no sign of that stopping .

Bioactive ingredients in apples

Pectin is a natural dietary fiber in apples, mainly found in the pulp. As a bioactive ingredient, pectin is one of the reasons why apples are classified as functional foods . Intake of pectin can reduce the body's absorption of sugar and fat, helping to reduce the risk of diabetes and heart disease.

Apple peels are also high in fiber — a good thing to have if you need a laxative.

In addition, apples contain a lot of polyphenols , which can promote health and reduce chronic diseases. According to the literature, scientists have identified more than 8,000 types of polyphenols in various plant foods. Since polyphenols are mainly found in the peel, it is believed that eating the whole apple directly can maximize the intake of polyphenols compared to drinking juice or eating jam.

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Anthocyanins are polyphenols that give apple skin its red color. A diet rich in anthocyanins may help improve heart health, and some researchers are trying to use anthocyanins to treat Alzheimer's disease.

Another key polyphenol in apples is called phlorizin. Scientists have been studying the role of phlorizin in controlling blood sugar for more than 100 years. Recent work has shown that this polyphenol plays an important role in regulating blood sugar levels by reducing the amount of glucose absorbed by the small intestine and increasing the amount excreted by the kidneys.

How many apples a day?

So, if apples are indeed functional foods that promote health, can they really keep the doctor away? Scientists also want to get the answer to this question.

A research team once analyzed the apple eating habits of more than 8,000 adults and their number of visits to the doctor, of whom about 9% ate an apple a day. Scientists found that those who ate an apple a day used slightly fewer prescription drugs than those who did not eat apples, but the number of visits to the doctor for both groups was roughly the same.

If one apple a day isn't enough to stay healthy, how about two or even three?

European researchers found that 40 adult volunteers improved their heart health by eating two apples a day, and Brazilian scholars found that eating three apples a day helped 40 overweight women lose weight and lower their blood sugar levels.

While an apple a day may not significantly reduce prescription medication or doctor visits, this dietary habit is indeed richer in fiber and more naturally healthy.

References

Does an apple a day really keep the doctor away? A nutritionist explains the science behind 'functional' foods

Planning and production

Source: World Science

Editor: Cui Yinghao

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