“Beauty King” in this book pointed out that eating carrots, celery, etc. will make the skin darker.
Summer sunshine is strong and many people who fear the sun have such questions. Does eating these vegetables really make the skin dark?
Carrots and most of the dark green or red and yellow fruits and vegetables contain carotenes, especially beta-carotene, which can be converted into vitamin A in the body after consumption.
The conversion of beta carotene to vitamin A
Vitamin A, also known as retinol, is an essential trace nutrient for humans. It is a component of the photoreceptor (rhodopsin) in the retina that maintains normal visual function and maintains the health of epithelial cells.
The structure of rhodopsin is the central blue region
Photosensitivity is an important characteristic of β-carotene and vitamin A.
Many sunscreen products emphasize a concept that can effectively prevent UVA and UVB. They are two different wavelengths of UV light. Mechanisms that have been thoroughly studied are: UVA wavelengths of 315 to 400 nm will make the skin tan; UVB wavelengths of 280 to 320 nm will cause skin redness and sunburn.
UVA and UVB damage to the skin
Due to the structure of long-chain conjugated polyenes in the molecule, both beta-carotene and vitamin A can strongly absorb ultraviolet light and emit orange fluorescence. The maximum absorption wavelength of the two is 326 to 445 nm, which can absorb a large amount of ultraviolet light in the UVA section.
Therefore, accurately speaking, long-term overdose of carrots will cause yellowing of the skin and cause carotene-induced jaundice.
A large number of foods with long-term consumption of carotene, such as papaya, citrus, and mango, may have different degrees of skin yellowing, especially in the palms and soles. Gradually relieved after discontinuation, the sclera and oral mucosa were not affected, and no other abnormalities were found.
Carotenoid patients with yellow skin disease
At the same time, β-carotene is also a drug (trade name Carlow) used to treat erythropoietic protoporphyrinosis.
Porphyria, also called hemochromatosis, is a metabolic disease caused by abnormal production and excretion of porphyrins. Porphyrins are substances that are very sensitive to light. If exposed to excessive sunlight, the skin can cause blisters and ulcers. It can also cause nervous system diseases. It can even cause death in the worst case. Transfusion can relieve symptoms.
Therefore, this disease is also known as “vampire disease.” Historically, George III of England was said to suffer from porphyria.
Beta-carotene and porphyrin have similar maximum absorption spectra and can act as a shielding agent in keratin after administration to increase the tolerance to sunlight.
The adverse reaction is: There may be different degrees of skin yellowing.
Of course, any food should be adequate.
Carotene in food is the safest form of vitamin A intake.
Vitamin A excess as fat-soluble vitamins can lead to accumulation of poisoning, manifested as loss of appetite, itchy skin, dry hair, infants and young children sensitive to it, should be used with caution, excessive intake in early pregnancy will be teratogenic.
The accumulation of carotene is almost non-toxic (precautions still need to be used with caution), beta-carotene is absorbed through the bile after oral administration, most of them are stored as prototypes in each tissue, and the small part is peroxidized in the liver when required by the body. The role of vitamin A conversion.
Just eat about 0.85 lemons or 1/2 carrots or 1 mango or 1 asparagus daily to meet the needs of carotene or vitamin A.