很多醫學研究証實，多吃深海魚有助減低患上心血管病的風險，專家更指出每周進食三餐魚肉，可減低慢性疾病的死亡率達25%。然而，很多魚都含水銀，常吃大量深海魚，便有機會攝取過量水銀，長遠可引致慢性中毒。那究竟深海魚是多吃有益，還是少吃為妙呢? 又究竟吃多少份量及吃那些品種才能既獲得其中的好處，又可避免攝取過量水銀?
多吃有益?!
吃魚可減低患慢性病的死亡風險，與其脂肪含量較牛肉和豬肉等紅肉低，及蘊含豐富奧米加-3脂肪酸有關。1安士(約28.4克)的魚肉含約1-3克脂肪，當中飽和脂肪只佔其總脂肪酸的25至30%(註: 飽和脂肪會增加人體內“壞”膽固醇，增加患心臟病的風險)，相比紅肉一般飽和脂肪酸的含量可達50%或以上，大大降低日後患心血管病的機會。此外，奧米加-3脂肪酸如EPA具抗炎功效，可減低血管因發炎而堵塞的機會; 幫助膽固醇代謝，降低壞膽固醇的水平; 其中DHA則對腦及視網膜健康及發展有莫大裨益。
少吃為妙?!
然而，曾有由美國獨立組織GotMercury.Org的調查發現，在洛杉磯出售的吞拿魚壽司，其水銀含量較美國食物及藥物管理局(FDA)建議的高出逾八成，部份樣本更達不適宜食用的水平，實在令一眾嗜魚之人卻步。水銀天然存在於土壤、岩石和煤炭中，從燃煤發電廠和其他來源進入空氣，再進入水中，小魚因吃浮游生物而吸入水銀，而水銀會積聚於小魚的體內無法排走，因此，當大魚捕食小魚後，小魚體內的水銀便會積存在大魚體內，故魚的體積愈大，累積的水銀將愈多。攝取太多水銀可致慢性中毒，有機會破壞中樞神經系統，削弱大腦功能。孕婦吸入過量水銀，更會損害胎兒的神經系統，影響胎兒的腦部發展。
那到底應多吃深海魚，還是少吃為妙呢? 請密切留意下一期的月刊，我們將討論如何選擇深海魚及建議的攝取量。
Deep sea fish- helpful or harmful?
It was clinically proven in a number of medical researches that eating deep sea fish can reduce the risk of coronary artery diseases. Experts have further stated that by eating fish three meals a week, one can reduce the death rate of chronic disease by up to 25%. However, as mercury can be found in most fish, one risks excessive intake of mercury by eating too much deep sea fish, leading to chronic poisoning. So, are deep sea fish helpful or harmful? Which types and what amount of deep sea fish should we eat to maximize the benefits and avoid excessive intake of mercury?
Benefits
Eating fish can reduce the death rate of chronic diseases. Fish’ fat content is significantly lower than red meat, e.g. beef and pork, and is rich in omega-3 fatty acids.
1 ounce (28.4grams) of fish contains roughly 1-3 grams of fat, of which only 25-30% are saturated fat (NB. Saturated fat can increase the ‘bad’ cholesterol level in a human body and thus, increase the risk of coronary diseases), compared to up to 50% or more in other red meats, thereby reducing the risk of coronary artery diseases. Furthermore, omega-3 fatty acids, such as EPA possess anti-inflammatory character, which can reduce the risk of blood vessel blockage caused by inflammatory; help cholesterol metabolism and lower the ‘bad’ cholesterol level; while DHA is beneficial to the retina and brain’s health and development.
Harm
The independent US organization, GotMercury.Org, reported that the Tuna sushi samples found in Los Angeles contains mercury levels that are 80% higher than the FDA recommendation, with some sample not even suitable for human consumption, raising concerns amongst fish lovers. Mercury is an element that can be found naturally in soil, rocks and coal, and passed into water through Coal-fired power plants and other sources. Fishes take in mercury through eating planktons, and the mercury cannot be passed away in their body. Therefore, when the deep sea fish ate the small fishes, the mercury stored in the small fishes would be accumulated in the huge fish body. Larger the fish, higher the mercury level. Excessive intake of mercury can cause chronic poisoning, and potentially damage the central nervous system, causing damage to brain function. Excessive intake of mercury in pregnant women might also affect the nervous system and brain development of the fetus.
So, is deep sea fish helpful or harmful? Stay tune to our next newsletter, where we’ll discuss the issues of how to choose deep sea fish, and the recommended intake level.
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