Many people like lemonade and think lemonade is good for health. Lemonade is rich in vitamin C and various minerals, which is good for whitening and skin. However, there are many "interesting" sayings on the Internet. Facts and rumors coexist. This paper introduces the relationship between lemonade and health, to see which are effective and which are just rumors.
Lemonade can't be drunk during the day?
Lemonade can only be drunk at night, and it is easy to get tanned by the sun during the day. This statement is very popular on the Internet. I did a simple search, and many professionals really agree.
The reason why lemonade is thought to be easy to tan may have nothing to do with the vitamin C it contains. Otherwise, the rumor should be that you can't eat orange kiwi fruit or VC effervescent tablets mixed with water during the day ... Lemonade is not suitable for drinking during the day because it contains "photosensitive substances", mainly coumarin.
Coumarin has an aromatic smell and has three structures: simple coumarin, furocoumarin and pyranose coumarin. Coumarin exists in citrus plants (orange oil, lemon oil, grapefruit, bergamot and so on). ), mostly furan coumarin. Coumarin has photosensitivity, which will make the skin black and seriously damage the skin.
The following are various mechanisms by which coumarin (psoralen) affects skin blackening. Simply put, it is to increase melanin synthesis, increase skin sensitivity to ultraviolet rays, increase melanocyte density, promote melanocyte growth, and protect melanocytes from being removed. ...
When coumarin contacts the skin, it is easy to cause skin blackening and even skin poisoning. Lemon oil is an extract of lemon, which has been widely used in cosmetics, but it has been banned in many countries because of its side effects. In recent years, it has been widely used in aromatherapy massage because of its coumarin, photosensitivity and melanogenesis. 200 1 there is a case in which two patients were massaged with aromatherapy oil and then exposed to ultraviolet rays. Bullous phototoxic skin reaction occurs after 48 ~ 72 hours, that is, "bullous skin" appears on the skin. Researchers believe that exposure to ultraviolet rays containing this citrus essential oil after massage will lead to health crisis [2].
Coumarin in citrus essential oil will not only cause problems to the skin, but also citrus juice or vegetables containing coumarin will directly contact the skin and be exposed to ultraviolet rays for a long time. There are so-called margarita burns abroad, but the official name should be "plant dermatitis". Margaret is a cocktail with lime, and the coumarin content in lime is several times that of lemon. When Margaret adds freshly squeezed lime juice in summer, she will inadvertently let her hands occupy the lime juice and then expose it to ultraviolet rays for several hours, which may cause local skin burns. After contact with lime or other citrus and vegetables (such as celery), there are many cases of ultraviolet burn or sunburn.
Citrus essential oil and juice directly contact the skin, which can easily lead to sunburn or sunburn. Can drinking lemonade also get sunburn? 20 17 studied and analyzed the concentration of coumarin in various citrus fruits and juices. Except concentrated lemon juice, the concentration of lemon itself is not high, 329ng/g, which is one-third of that of lime and less than 2% of that of grapefruit. The content of coumarin is about 16500mg or 16.5g based on 50g of lemon.
Besides citrus, celery (252ng/g), parsley (232 14ng/g), carrot (68ng/g), parsley (334ng/g), parsley (258ng/g) and other vegetables all contain more coumarin.
In a study published in 199 1, the Swiss federal public health office [7] tested four subjects and ate celery containing coumarin. Subjects ate 300 grams of celery root, which contained about 28.2 mg of coumarin, and then irradiated with ultraviolet rays. Their skin had no phototoxic reaction at all, but only one of them had a skin blackening reaction at the level of 10 mg of coumarin. Suntan takes about 600 lemons.
In a research paper [8] published on 20 10 in Germany, the daily drinking of citrus drinks and vegetables was tested, and it was concluded that coumarin in diet could not reach phototoxicity. It is reported that the phototoxicity of coumarin in diet should reach 45 mg, but the risk of direct contact with skin will be greater.
Brown University published two epidemiological studies in the past five years. A prospective study on 20 15 [23] analyzed the data of more than 654.38+million people, and found that people who eat more citrus fruits are more likely to suffer from basal cell carcinoma and squamous cell carcinoma, but how much higher? If you eat 1.5 oranges a day for 25 years, basal cell tumor and squamous cell carcinoma will increase by 16% and 2 1% respectively. A cohort study published in 2020 [24] analyzed the data of about1.20 thousand people in 27 years, and found that furocoumarin was not related to squamous cell carcinoma, but positively related to basal cell tumor, and the risk increased 1.6%. These are all related studies for your reference.
So far, no clinical trials have found that drinking lemon juice or lemonade can easily lead to sunburn or increase the risk of skin cancer. So from the research evidence, direct contact with citrus juice is easy to cause sunburn, but drinking lemon juice has not found the same effect.
Is lemonade acidic or alkaline?
Lemon juice has a pH of about 2 to 3 and is acidic, while lemonade is an alkaline diet, which can increase the alkalinity of urine, that is, reduce the acid load (or DAL) in the diet.
Whether food is acidic or alkaline has nothing to do with the pH value of the food itself. It depends on whether the "products" after digestion and metabolism in the stomach are acidic or alkaline. There used to be so-called ash analysis, which detected the acid load of food and divided it according to the ash produced after food was completely burned and the acidity and alkalinity of the solution dissolved in water. This method is very inaccurate and is basically not used in the study of food acid load. At present, the standard for evaluating food acid load is "potential renal acid load" (PRAL), that is, tracking various minerals in food, such as potassium, magnesium, calcium, phosphorus and protein. , calculate the pH value when the food reaches the kidney after metabolism. Food in protein is generally acidic, while fruits and vegetables contain more minerals, so they are alkaline. Lemon juice contains more minerals, so the PRAL value is about -2.5, which belongs to alkaline food.
Diet changes the pH value of urine, but it has no obvious effect on the pH value of blood ... The pH value of human blood is regulated by the kidney and strictly controlled between 7.35 and 7.45. To affect the pH of blood, you need to eat 8 kilograms of oranges to increase the pH of blood by 0.2. Therefore, the influence of diet on blood pH can be ignored.
Studies have found that increasing alkaline foods is related to improving various health problems. A literature review of 20 19 found that increasing alkaline foods such as vegetables and fruits is related to improving insulin resistance, diabetes, hypertension, chronic kidney disease and bone health. However, the study also pointed out that the combination of alkaline diet is very similar to DASH diet specially designed to improve hypertension, that is, there is no necessary correlation between alkaline diet and health.
From the research evidence, there is no clinical study to prove that potential renal acid load PRAL can directly affect health, and lemonade is only one of many alkaline foods, and its alkalinity level is not high, so there is not enough evidence to prove that it affects health through alkalinity.
Lemonade is anti-aging?
Animal experiments show that drinking water containing lemon polyphenol antioxidant for a long time can not only resist aging, but also prolong life. A study published on 20 19 in Japan found that the polyphenol antioxidant lemon polyphenol contained in lemon can resist aging. In this study, rats were divided into two groups. One group drank water containing lemon polyphenols throughout its life cycle, while the other group drank ordinary water. The results showed that the average life span of mice drinking lemonade was prolonged by 3 weeks, which was equivalent to 4% of the life span of mice, and the mice drinking lemonade delayed the aging time. Further analysis found that lemon polyphenols may change the intestinal flora of mice and have anti-aging effect.
In another animal experiment, it was found that after ultraviolet irradiation, compared with the mice that did not drink lemonade, the wrinkles, thickness and aging degree of the skin of the mice that drank lemonade decreased, while the collagen of the skin increased. The results showed that the activities of various antioxidant enzymes, GPx, SOD and CAT in the cells of mice drinking lemonade increased. People think that drinking lemonade may help prevent premature skin aging caused by oxidative stress.
So far, no one has found that lemonade can help improve aging. However, taking more vitamin C is related to reducing skin wrinkles. In 2008, an epidemiological study based on 4025 British women found that more vitamin C in the diet was inversely proportional to facial wrinkles and dry skin.
External use of vitamin C can improve skin aging. [16] In a double-blind controlled clinical trial conducted in France in 2003, subjects received ointment containing 5% vitamin C. After 6 months, dermatologists and subjects scored themselves, and the skin of subjects who used vitamin C improved obviously, wrinkles decreased and skin elasticity increased. The conclusion is that ointment containing 5% vitamin C can effectively improve skin aging caused by ultraviolet rays. In another double-blind controlled clinical study 1999, it was also found that the use of external lotion containing vitamin C was helpful for skin anti-aging. This time, the subjects used an external lotion containing vitamin C and a placebo. It was found that vitamin C emulsion could significantly improve skin aging after 3 months.
Therefore, animal experiments have found that drinking lemonade is helpful to anti-aging, but no similar findings have been found in human clinic. A certain amount of vitamin C is helpful to improve skin aging, but a lemon only contains about 30 mg of vitamin C. If you want to supplement vitamin C, eating a big orange (100 mg) or taking vitamin C supplements directly may be more effective.
Lemonade can improve other health problems.
Lemonade improves kidney calculi-Research papers point out that lemonade can significantly reduce the risk of kidney calculi. Lemon can prevent kidney calculi. In addition to lemon diuresis to increase urine excretion, potassium and citric acid are also helpful. Citric acid can be combined with calcium in urine to reduce calcium saturation in uric acid, and citric acid can be combined with calcium oxalate to prevent crystal stones. There is a clinical study. 12 patients with low calcium kidney calculi citrate excretion drink about113g lemon juice mixed with 2 liters of water (almost 4 lemons) every day for 6 days. The results showed that the average citrate excretion of subjects increased by 69%. Seven cases (58%) recovered to normal citrate excretion. The conclusion of this study is that lemonade can be used as an auxiliary method to treat calcium oxalate kidney calculi with low citrate excretion. However, some scholars disagree that lemonade can prevent or treat kidney calculi. However, lemonade may increase the water consumption of patients in kidney calculi, which may reduce the risk of kidney calculi.
Lemon juice helps to reduce uric acid-A preliminary clinical study in 2065438+05 divided 75 subjects into gout group, hyperuricemia group and healthy control group. Subjects drank 2 liters of freshly squeezed juice and 2 lemons every day for 6 weeks. Results: The serum uric acid of all subjects decreased, with an average of 65,438 0.6 mg/dl in gout group, 65,438 0.3 mg/dl in hyperuricemia group and 65,438 0.3 mg/dl in healthy control group. From the experimental results, lemonade can not only reduce uric acid, but also reduce the risk of uric acid and gout in kidney calculi by increasing the pH value of urine. In 20 17, researchers from Huazhong Agricultural University in China also concluded that lemonade is helpful to reduce uric acid in mice and small-scale clinical trials.
abstract
From the research evidence, we really need to be careful not to expose your skin to the sun after direct contact with lemon juice and lemon essential oil, but after drinking lemonade, sunbathing won't make you tan more easily.
Lemon contains vitamin C, lemon polyphenols and other beneficial substances, which are helpful to improve health, including reducing uric acid, and may reduce the risk of kidney calculi. However, there is not much evidence about the anti-aging and other health problems of lemonade in human clinical research.
The biggest influence of lemonade on us may be to replace sugary drinks, especially in summer, which may make us drink more water and help our health.