Seafood is delicious and allergies are hard to prevent. Why are some people allergic to seafood? Seafood contains a certain amount of Histamine, which is an active amine compound. As a chemical conductive substance in the body, it can affect many cell reactions, including allergies, inflammatory reactions, gastric acid secretion, etc., and can also affect nerve conduction in the brain, which will cause people to want to sleep and other effects. Histamine exists in mast cells and also in the mucosal tissues of lung, liver and stomach. It plays an important role in the regulation of allergy and inflammation. Histamine is a kind of chemical message, which is involved in sleep, hormone secretion, body temperature regulation, appetite and memory formation, etc. In addition, it can also cause itching, sneezing, runny nose and other phenomena. In addition, histamine binds to the receptor on vascular smooth muscle (H 1R), which leads to vasodilation and local edema. Histamine can make the tracheal smooth muscle of the lung contract, causing respiratory tract stenosis and dyspnea, and the intestinal smooth muscle contracts to reduce blood pressure and increase heartbeat.
Seafood contains a certain amount of histamine. Once histamine is absorbed by the human body and enters the immune system, it will cause allergies. Most people have enzymes that decompose histamine in their bodies, so there will be no allergic phenomenon; However, it is worth noting that if the intake of histamine exceeds the tolerance range of the human body, it may cause allergic poisoning. However, the so-called allergic poisoning and allergy are not the same. People who are allergic to seafood will have symptoms as long as they ingest a small amount of histamine; However, allergic poisoning is caused by excessive intake of histamine. Therefore, even normal people who contain histamine-decomposing enzymes may still have allergic poisoning. Because the symptoms of allergic food poisoning and allergy are almost the same, misdiagnosis often occurs when seeking medical treatment, so patients should tell their doctors in detail what they have eaten and how much, so as to make a correct diagnosis.
The onset of seafood allergy poisoning is fast, often 0.5~ 1 hour after eating, sometimes as long as 5 minutes, and for a long time as long as 4 hours. Symptoms are mild at onset, recovery is quick, and occasionally death occurs. Often manifested as blushing, dizziness, headache, heartbeat, palpitation, chest tightness, shortness of breath, swelling of the face and lips, numbness of the tongue and limbs, nausea, vomiting, itchy skin and so on.
First, skin symptoms: skin congestion, eczema, itching, urticaria, vascular edema. These symptoms are most likely to appear in the face, neck, ears and other parts.
1, urticaria: skin itching often occurs first, followed by wheal, which is bright red or pale and skin-colored, and a few patients have edematous erythema. Wind masses vary in size and shape, and the onset time is uncertain. The wind mass gradually spread and merged into pieces. Due to dermal papilla edema, it can be seen that the epidermal hair follicle mouth is sunken downwards. The wind mass lasts for several minutes to several hours, and a few of them can be extended to disappear after a few days, leaving no trace. Rashes occur repeatedly in batches, especially in the evening. Wind masses are often widespread or limited. Sometimes it is complicated with vascular edema, and occasionally bullae are formed on the surface of the wind mass. Some patients may be accompanied by nausea, vomiting, headache, head swelling, abdominal pain, diarrhea, and severe patients may also have chest tightness, discomfort, pale face, accelerated heart rate, weak pulse, decreased blood pressure, shortness of breath and other systemic symptoms.
2. Eczema: At first, the lesions were mostly dense miliary papules, papules or small blisters, and the basal flush gradually merged into pieces. Due to scratching, the papules, papules or blisters showed obvious punctate exudation and small miliary surface after being scratched at the top, and the edge was unclear. If secondary infection, inflammation is more obvious, pustules, pus scabs, folliculitis, furuncle and so on can be formed. Consciously severe itching. Eczema caused by allergy may or may not be accompanied by gastrointestinal symptoms such as nausea, vomiting and diarrhea.
3, angioneurotic edema: the skin and subcutaneous tissue are thickened, the boundary is hard but there is no finger indentation, and the skin color and temperature are normal; In addition to feeling swollen or hot, there are generally no sensory abnormalities such as pain and itching.
Second, gastrointestinal symptoms: nausea, vomiting, abdominal pain, bloating, diarrhea, mucus-like or watery stools, and individuals may also have allergic gastritis, enteritis and celiac disease.
Third, nervous system symptoms: such as headache, dizziness, etc., more serious symptoms may occur such as a sharp drop in blood pressure, loss of consciousness, poor breathing and even anaphylactic shock.
What are the methods to prevent seafood allergy?
Most patients with seafood allergy are allergic because of excessive consumption of seafood. The cause of seafood allergy is that seafood is rich in a large number of heterogeneous proteins, which directly or indirectly activate immune cells, cause the release of chemical mediators, and then produce a series of complex biochemical reactions. When antibody and antigen work together, the human body will show allergic symptoms.
1, avoid immature seafood: the bacteria in seafood are mainly Vibrio parahaemolyticus, etc., which have strong heat resistance and can only be killed above 80℃. In addition to the bacteria brought by water, there may be parasitic eggs in seafood, as well as bacteria and virus pollution caused by processing.
Generally speaking, it takes 4-5 minutes to cook in boiling water to be completely sterilized. Therefore, we must be careful when eating unheated seafood such as "drunken crab", "raw sea urchin" and "marinated seafood in soy sauce", and ensure the freshness and hygiene of the fish when eating sashimi.
2. Don't eat dead seafood: Shellfish itself carries a relatively high amount of bacteria, and protein decomposes quickly. Once it dies, it will multiply germs and produce toxins, and the unsaturated fatty acids contained in it are also prone to oxidative rancidity. Stale shellfish also produce more amines and free radicals, which pose a threat to human health.
After buying live shellfish, you can't store them at home for too long. Cook them as soon as possible. People with allergies should pay special attention, because sometimes allergic reactions are not caused by seafood itself, but by substances in the process of protein decomposition of seafood.
3, do not drink with beer: it is best not to drink beer when eating seafood. Seafood such as shrimp and crab will form uric acid after metabolism, and excessive uric acid will cause gout, kidney calculi and other diseases. If you eat a lot of seafood and drink beer at the same time, it will accelerate the formation of uric acid in the body.
Therefore, when eating a lot of seafood, don't drink beer, otherwise it will have adverse effects on your health.
4. Do not eat with fruits: Seafood such as fish, shrimp and crab are rich in nutrients such as protein and calcium. Fruit contains more tannic acid. If you eat fruit immediately after eating seafood, it will not only affect the human body's absorption of protein, but also combine calcium in seafood with tannic acid in fruit to form insoluble calcium, which will stimulate the gastrointestinal tract and even cause symptoms such as abdominal pain, nausea and vomiting.
Therefore, it is best to eat seafood and fruit more than 2 hours apart.
5, do not drink with tea: the reason why it is not suitable for drinking tea after eating seafood is similar to the reason why it is not suitable for eating fruit. Because tea also contains tannic acid, it can also form insoluble calcium with calcium in seafood. Eating seafood before or after eating seafood will increase the chance of combining calcium with tannic acid. Therefore, it is best not to drink tea when eating seafood. In the same way, it is also best to have an interval of more than 2 hours.
6, shrimp avoid eating with vitamin C: Arsenic, which is usually harmless to the human body, can be converted into toxic arsenic under the action of vitamin C.
7. Be careful to eat seafood during taking medicine: According to the quality of your body, for example, when some people are taking medicine, you must be especially careful to eat seafood;