Stir-fried pork liver, marinated pork liver, sneaked pork liver, spicy pork liver, cold mixed pork liver, pork liver porridge, pork liver soup, pork liver mud, pork liver fried rice…
The saying that pig liver can improve eyesight has been circulating among the people.
The well-done pork liver is tender and delicious, and melts at the entrance. The pork liver has a very special taste, mellow and delicious, which makes people drool.
So, can pork liver really improve eyesight? Can carrots and medlar, which are also highly praised, [improve eyesight]?
Dr. Clove told you carefully one by one.
Pig liver improves eyesight? Take it easy!
1. Average intake [one bite] is enough
Liver is an important organ for storing vitamin A in animals. 100 grams of pig liver contains about 5,000 micrograms of vitamin A.
One of the important physiological functions of vitamin A is to maintain the normal structure of cornea and the normal function of retina, which plays an important role in maintaining normal vision.
If vitamin A is lacking, symptoms such as dry eye and night blindness will occur.
Therefore, for people who lack vitamin A, pig liver can indeed help supplement vitamin A quickly and has certain effect on maintaining eyesight health. From this perspective, the statement of pig liver [improving eyesight] also has some truth.
However, the more vitamin A is eaten, the better. Vitamin A is fat soluble and is not easily excreted from the body. Excessive intake of vitamin A may bring toxicity, lead to abnormal bone growth, and has a greater impact on pregnant women. The upper limit for adults to consume vitamin A is not more than 3,000 micrograms per day.
The Dietary Nutrition Guidelines for Chinese Residents recommend that the recommended daily vitamin A intake (RNI) for adult males is 800 micrograms and that for adult females is 700 micrograms, which translates into the weight of pig liver, which is about 14 ~ 16 grams, which is about the amount of one mouthful of pig liver.
2. Pig liver is not the best choice for vitamin A
First of all, there are often more heavy metals and veterinary drug residues in animal liver.
Pig liver can be described as the largest [detoxification device] and poison [transfer station] in pig body. Toxic and harmful substances entering the body, such as heavy metals, veterinary drugs and pesticides, are metabolized, transformed, detoxified and discharged out of the body in the liver. When liver function drops or toxic and harmful substances are ingested more, these harmful substances will accumulate in the liver.
Many investigations of liver foods such as pig liver sold in the local market in our country have found that the residues of heavy metals and veterinary drugs in the livers of animals such as pig liver are usually relatively high, and eating more is really not good for health in what.
Secondly, pork liver is not the only dietary way to obtain vitamin A.
For most residents in our country,-carotene is the main dietary source of vitamin A, and it has no toxicity of vitamin A. Even if too much carotene is taken from vegetables and fruits, the result is only carotene excess, which is manifested as yellowing of skin, but it is not harmful to health. After stopping, yellow will fade away.
On the whole, the rich vitamin A in pig liver does have some benefits for maintaining eyesight, but pig liver is not the only way to obtain vitamin A, nor is it the best food source to obtain vitamin A.
As an important metabolic organ of animals, pig liver is more likely to enrich some harmful substance residues such as heavy metals and veterinary drugs. The cholesterol content of pig liver is also very high. It is not a good choice to eat a large amount of pig liver for the so-called [eyesight improvement] effect.
If you want to be poor, eat more carrots?
During World War II, the British Air Force terrified the Germans with its precise strike force. People asked: Why can the British Air Force accurately drop German planes even in late-night operations?
At that time, the British Ministry of Food said that the magic weapon for pilots to win was to eat carrots. This statement quickly became popular and even set off a craze for eating carrots in the local area.
Can carrots really improve eyesight?
One of the reasons why eating carrots is beneficial to eyesight is influenced by the idea of “supplementing shape with shape”. They believe that carrots cut open are like human eyes, with pupils, irises and radioactive lines. Large amounts of carotene can promote blood flow to eyes, protect eyesight and brighten eyes.
1. Effectively improve night blindness
Indeed, eating carrots is good for the eyes, because they are rich in carotene, which is converted into vitamin A, retinol, which is the key to synthesizing rhodopsin, a photosensitive substance in visual cells. Therefore, the common symptoms of vitamin A deficiency are night blindness and vision loss (which can lead to total blindness in severe cases).
According to the survey, about 250,000 to 500,000 children worldwide become blind due to vitamin A deficiency every year. In malnourished people with vitamin A deficiency such as Nepal and India, vitamin and-carotene supplements can promote people’s night vision.
2. It is not effective for myopia.
Vitamin A is mainly used to improve night blindness and has no what help for myopia.
Moreover, carrots are not the only foods rich in-carotene. Pumpkins, sweet potatoes and dark green leafy vegetables (spinach, spinach, broccoli, etc.) are all good sources of-carotene, and they do not look like eyes.
They can help our eyes filter out visible light of high-energy wavelengths that may damage the retina, and can also prevent blindness caused by macular degeneration, which is common in the elderly.
Returning to the beginning story, why did British pilots play so accurately during World War II? Only a few decades later did people realize that the real secret weapon of the Royal Air Force at that time was radar technology.
[Carrot said] It’s just a blind trick by its intelligence department.
Lycium barbarum
Others say that eating medlar improves eyesight because it contains lutein, which is beneficial to eyesight. Lutein is what? Is eating medlar really useful?
Lutein, also known as plant lutein, plays a certain role in preventing and treating visual loss, blindness, cataract and other eye diseases caused by senile ocular retinal macular lesions.
A common disease of old age [age-related macular degeneration] (AMD), usually occurs after the age of 50, and the higher the incidence rate is with age. The symptoms of this disease begin with vision loss, which will lead to blindness after deterioration.
A large number of studies have confirmed that after eating lutein-rich foods or lutein supplements, the concentration of lutein in the blood will increase, and the lutein in the retinal macula will also increase, and the symptoms of [age-related macular degeneration] will be improved proudly.
However, Lycium barbarum is usually used as a seasoning, and the amount of lutein available is very limited.
The reference intake of dietary nutrients for Chinese residents (2013) recommends that lutein be taken in 10 mg per day. Considering that lutein content in many foods is not low, reasonable diet and proper eating of some vegetables and fruits every day can completely obtain sufficient lutein.
Whether it’s pork liver, carrot or medlar, these legends can improve eyesight. Eat a little if you like, but don’t be too superstitious about their effect on eyes. Balance is the real truth.