Chinese people like to eat fish, but with the improvement of living standards, people have higher and higher requirements for dietary safety. Many people are worriedWill fish and aquatic products be contaminated by heavy metals?, such as the risk of mercury pollution, how to choose fish and how to eat it more healthily? Let’s answer these questions one by one~
The benefits of eating fish are not just for brain health
Fish meat is a kind of "white meat". Compared with pork, beef and mutton, fish meat isLower in calories and saturated fat, higher in minerals such as calcium, can be used as a high-quality protein source during weight loss and fat loss periods.
and,Rich in fishGlutamic acid, aspartic acid, etc.Presents umami amino acids, giving fish its own umami flavor. This allows us to cook fish without having to go through deep processing of heavy oil, heavy salt, and high sugar. We only need to steam or boil soup to make it delicious and attractive.
Plus a lot of fish (especially fatty sea fish and some freshwater fish)The body is high in unsaturated fatty acids such as DHA, it is also beneficial in promoting the development and health of brain cells and visual cells. It is very suitable as a good food source for daily supplementation of DHA. It is a highly recommended food for infants and young children whose brains are in a period of rapid development, as well as for the elderly and young people who need to supplement DHA.
in addition,The vitamin D content in many fish is not low, while the vitamin D content in other common foods is not high. For people who lack sun exposure and lack vitamin D in food, it is very suitable to eat more fish.
Does fish contain heavy metals?Which fish have higher levels of heavy metals?
Some heavy metals in the water, such as mercury, lead, arsenic, and cadmium, can be continuously enriched in the fish through the water or algae containing heavy metals, and their metabolism takes a long time.
In the past, it was thought that large deep-sea fish were more susceptible to heavy metal pollution than freshwater fish. This conclusion has certain truth and is also supported by corresponding survey and research results [1].
However, heavy metal pollution in fish is also related to factors such as different sea areas, fish types and ages. Globally, there are general rules for the heavy metal content in fish:
Carnivorous fish > omnivorous fish and herbivorous fish;
Large fish > small fish;
Older fish > younger fish.
For example, the "not recommended" (high mercury content) level listed by the U.S. Food and Drug Administration includes large carnivorous fish such as shark, swordfish, tilefish, big-eared mackerel, bigeye tuna, and marlin [2].
Different sea areas also have an impact on the metal content of fish body weight. According to the results of a survey, as far as my country is concerned, the mercury content in wild fish in the Bohai Sea area of the East China Sea is higher than that in farmed fish; the mercury content in marine farmed fish in the South China Sea is higher than that in wild fish [3].
At the same time, in this survey, carnivorous fish such as grouper, golden thread fish, catfish, mandarin fish, etc. showed higher mercury content, which is also in line with the general rule we mentioned above.
The Hong Kong Center for Food Safety also has tips on mercury levels in fish, which also lists carnivorous fish with high mercury levels such as golden snapper, swordfish, tilefish, bigeye tuna, blue flag tuna, swordfish, and shark. This is similar to the “not recommended for consumption” category given by the U.S. Food and Drug Administration [4].
Furthermore, I would like to remind everyone that even if they are the same fish,You should also avoid choosing those who are overweight, This is mainly because larger weight means that the fish is older. Not only is the meat not necessarily tender, but it is also easier to accumulate more heavy metals through eating and drinking.
However, you can rest assured that the above-mentioned survey results also point out that the current mercury content of aquatic products in my country is generally far below the national standard limit.
Considering that the fish intake of the Chinese population does not meet the standards, the daily mercury exposure caused by the intake of aquatic products for the entire population is generally lower than the tolerable weekly intake of food methylmercury of 1.6 μg/kg body weight issued by the Joint Expert Committee on Dietary Exposure and Food Additives, and the health exposure risk is generally at an acceptable level [3].
Whether it is the U.S. Food and Drug Administration, the Hong Kong Center for Food Safety, or the Dietary Guidelines for Chinese ResidentsRecommendedLow-mercury, high-DHA fish, including:Salmon, seabass, sardines, anchovies, large yellow croaker, tilapia, etc.
Some shellfish also fall into the safe category of low mercury, such as clams, crabs, oysters, scallops, etc., which are high-quality and low-priced, and are also available.
Want to stay away from heavy metals as much as possibleThe way you eat is also particular.
In addition to being familiar with which fish may contain higher levels of heavy metals, there are also some techniques to minimize our risk of ingesting heavy metals during the cooking and processing of fish.
1.Try to avoid several large fish that are not recommended above
The large fish and carnivorous fish mentioned above should be avoided as much as possible, especially grouper, golden thread fish, catfish, mandarin fish, etc. that are common in my country.
2.Pair it with some ingredients that promote the body’s excretion of heavy metals
The human body has the ability to remove and excrete heavy metals. As long as you don't eat a lot of fish with high heavy metal content for a long time, the possibility of causing harm is generally not great.
If you can add some foods that promote the body's elimination of heavy metals during the cooking process, such as coarse grains, vegetables and fruits rich in dietary fiber, you can better prevent injuries.
3.Food diversity
We can give full play to the advantages of food diversification, which not only reduces the use of fish that may contain heavy metals, but also gives full play to the different types of nutrients in different foods and the health effects of different nutrients working together to minimize, share, and offset the health risks that may be caused by heavy metal intake.
For example, if we are worried that the presence of heavy metals will damage the brain and nervous system, we can eat more foods that are beneficial to the health of the brain and nervous system, such as DHA-rich salmon, original nuts, etc.
If you are worried that heavy metals will increase the metabolic burden on the liver, you can eat more fresh fruits and vegetables rich in vitamin C.
All in all, diversifying food is beneficial in terms of enriching nutrients, preventing chronic diseases, and combating the health hazards of heavy metals.
Finally, you should also pay attention to the amount limit when eating fish. According to the recommendations of the Dietary Guidelines for Chinese Residents, normal adults are recommended to eat fish twice a week, approximately 300 to 500 grams.
When cooking fish, it is better to steam it, and try to avoid frying and grilling to avoid destroying the unsaturated fatty acids in the fish and preventing increasing the content of carcinogens due to frying and grilling.
References
[1] Ye Haimei, Wu Yongning. Comparison of heavy metal indicators in fish and processed products [J]. Chinese Journal of Food Hygiene, 2009, 21(3): 273-276.
[2]https://www.fda.gov/Food/FoodborneIllnessContaminants/Metals/ucm115644.htm
[3] Xu Xi, Yan Chonghuai. Analysis of total mercury pollution characteristics of aquatic products in China and health exposure assessment [J]. Chinese Journal of Food Hygiene, 2022, 3 (17): 104-109.
[4]https://www.cfs.gov.hk/sc_chi/index.html
Planning and production
Author | Wang Lu, registered nutritionist
Review丨Ruan Guangfeng Director of Science and Technology Department of Kexin Food and Nutrition Information Exchange Center
Planning丨Yang Yaping
Editor-in-charge丨Yang Yaping and He Tong
Reviewer丨Xu Lai Linlin