**3. The importance of nutrition with shellfish**

Shellfish are rich in low-calorie lean protein, essential oils, and micronutrients. Most of the fats found in shellfish are in the form of omega-3 fatty acids, which have benefits for improving brain and heart health. Shellfish are rich in iron, zinc, magnesium, and vitamin B12, all of which play important roles in our bodies. For example, 85 g oysters have almost 100% of the daily value for zinc. Shellfish are most nutritious when steamed. Fried shellfish may contain ingredients such as additional calories, refined carbohydrates, added salt. With its impressive nutritional content, shellfish has low calories. This makes them excellent foods to eat while trying to lose weight. Protein-rich foods can help you lose or maintain weight by preventing you from consuming calories. Due to its omega-3 fatty acid content, it can lead to a greater feeling of satiety than fish and may help to lose weight faster than other high-protein foods. A study of overweight adults found that those who consumed more omega-3 fatty acids on a calorie-restricted diet felt significantly fuller after meals than those who consumed less omega-3 on the same diet [25]. In order to obtain the maximum benefit from shellfish as food, it is extremely important that the environmental conditions in which the consumed products are supplied are healthy, as well as the depuration of the products by the companies and the storage conditions of the packaged products until the expiry date without breaking the cold chain.

Shellfish have microelements that can improve the health of heart, including omega-3 fatty acid and vitamin B12. Studies have shown that getting omega-3 fatty acid from fish and shellfish is linked to a lower risk of heart disease. This is probably because omega-3 have anti-inflammatory effects. In a study of 18,244 healthy men in China, those who ate more than 200 grams of omega-3-rich shellfish per week were 59% less likely to die from a heart attack than those who ate less than 50 gram per week. Inadequate B12 intake has also been linked to high blood levels of homocysteine, a protein that may increase your risk of heart disease. Therefore, foods rich in vitamin B12 may protect against heart disease. Studies have identified insufficient B12 and omega-3 levels as risk factors for problems with brain development in children and healthy brain function in adults. Some research also suggests that vitamin B12 and omega-3 fatty acid may improve each other's activities to improve brain health. In a study of 168 adults with mild mental disorders it was found that B vitamins slowed the progression of brain problems in those with lower levels of omega-3 fatty acids compared to those with low levels. Shellfish contain zinc, which


**Table 1.**

*Nutrition facts of 85-gram of different types of shellfish (https://fdc.nal.usda.gov/ndb/).*

strengthens the immune system. This mineral is necessary to strengthen the cells that make up the immune defense of our body. It also acts as an antioxidant, protecting against damage caused by inflammation. A study of 62 healthy adults over the age of 90 showed that zinc deficiency reduced the activity of certain immune cells. Shellfish are full of protein and healthy fats that can aid weight loss. It is also rich in omega-3 fatty acids, vitamin B12 and zinc, which support a healthy brain, heart, and immune system (**Table 1**) [26].

#### **4. Negative effects of excessive consumption of shellfish**

Although shellfish are highly nutritious, they have some disadvantages when consumed excessively. Shellfish have the potential to accumulate heavy metals such as mercury or cadmium from the environment. The accumulation of these compounds in our bodies can lead to organ damage and other health problems. One study showed that shellfish in some regions may contain cadmium at twice the recommended daily dose. The Food and Drug Administration recommends that adults eat 85–140 grams of low-mercury fish twice a week. If the number of shellfish we eat in a week is equal to or less than this, there is no danger in terms of heavy metals. Consuming shellfish obtained from waters where polluting factors prevail causes many food-borne diseases. Mollusks such as oysters and mussels accounted for more than 45% of seafood-related foodborne illness cases in the United States America (USA) from 1973 to 2006. Food poisoning from shellfish can be caused by bacteria, viruses, or parasites in the environment. Pathogens thrive in raw shellfish that are not properly refrigerated. Therefore, obtaining shellfish from clean waters, storing, and cooking them properly is the most effective way to prevent foodborne illness. Pregnant and nursing mothers, older adults, and people with compromised immune systems should avoid raw or improperly prepared shellfish [27, 28].

Shellfish is one of the top eight food allergens in the USA. Shellfish allergy typically develops in adulthood but can also occur in childhood. Symptoms of an allergic reaction to shellfish include vomiting and diarrhea, stomach pain and cramps, swelling of the throat, tongue or lips, hives, shortness of breath. In some cases, people with a shellfish allergy may experience a life-threatening anaphylactic shock that requires immediate treatment. Shellfish can accumulate different levels of heavy metals that can build up in your body and cause health problems. Diagnosing allergies to shellfish can be difficult and complex. Symptoms can vary from person to person, depending on metabolism, and may not always give the same reaction. People with shellfish allergies may not need to eat only these products to develop a reaction. A reaction may also occur on contact with cooked shellfish. Allergic

#### *The Effects of Shellfish Consumption Frequency for Human Health DOI: http://dx.doi.org/10.5772/intechopen.100405*

reactions to these creatures can also affect the skin, respiratory, digestive, and circulatory systems. Although these allergies are not very common in adults, they can occur at any age. In the case of this type of food allergy situation, it is important to consult an allergist who can determine what tests need to be done after diagnosis, decide whether it is an allergy, and advise patients on how to manage exposure and symptoms [29].

Allergies to shellfish occur when the immune system opposes the proteins found in these animals. When these proteins enter the body of individuals with allergies, the immune system overreacts and tries hard to fight against the antigens it sees as foreign. Some of these reactions occur due to the release of histamine, which causes allergy symptoms. Therefore, antihistamines can give effective results in such an allergic reaction. For people whose shellfish allergy is confirmed by further testing, the only treatment is to avoid these creatures altogether. In the event of exposure or a serious reaction, every second counts. Detecting the reaction early and administering epinephrine quickly can prevent worsening of the condition and possible death [30, 31].

History is very important for diagnosis in patients with suspected Shellfish allergy. The patient's history is necessary both for determining the severity of the disease and for planning diagnostic procedures. Therefore, before going to the doctor, review your complaints in detail. In general, those with suspected allergies,

