Canned tuna is an excellent, affordable source of protein, polyunsaturated fats and other nutrients. Sounds good, but how much can you eat before you need to worry about mercury?
The U.S. Food and Drug Administration has warned consumers about the health risks of mercury in fish. Should you be concerned? Mercury is found in canned tuna. But what about other fish?
Here are the main health concerns about mercury in fish:
Health Dangers Of Mercury
Many people depend on fish for essential nutrients, such as omega-3 fatty acids, but mercury contamination can add health risks.
Mercury is a neurotoxin, meaning that it can affect the brain and cause problems such as blurred vision, lack of coordination, and slurred speech. High exposures to mercury can even lead to death. Children exposed to high levels of mercury can also suffer slowed development, reduced brain development, birth defects, and even blindness. These health hazards are primarily associated with fish.
How Does Mercury End Up In Fish Anyway?
Mercury is naturally present in our environment but there can be relatively high concentrations in fish – particularly predatory fish.
In other words, it builds up as smaller fish get eaten by middle-sized fish, which get eaten by large fish, which get eaten by us. So the bigger the fish, the higher the likely mercury content.
Which Fish Contain High Concentrations Of Mercury
In 2011, a study of sharks found that their mercury concentrations were two to six times the recommended limit for human consumption. Even swordfish is considered a milder fish, but its high mercury content is still a concern. Other fish with high concentrations are Tilefish, King Mackerel, Tuna, Spanish Mackerel, Marlin, and Cod.
All fish contain trace amounts of mercury, which do not pose health risks for most people. The best way to avoid mercury in seafood is to stay away from the larger types of fish that are subject to high concentrations. Pregnant women and young children should limit their intake of fish and choose varieties with low mercury levels, as fish that contain high concentrations of mercury can be harmful to a developing fetus or newborn.
How Much Mercury Can Be Consumed
You may be wondering: how much mercury can you consume in fish? The amount of mercury in fish varies greatly, depending on the type and quantity of fish you consume. You can calculate your mercury intake by looking at the fish's weight or other factors. Generally, the lower to medium-high fish are shrimp, scallops, sardines, wild/Alaskan salmon, tilapia, and salmon.
According to Food Standards Australia New Zealand: The maximum dose of mercury set for the general population is 3.3 micrograms per kilogram of body weight per week. The guidelines assume all mercury in fish is the more harmful methylmercury as a worst case scenario.
Get The Latest By Email
The dose for pregnant women is approximately half this value – 1.6 micrograms per kilogram of body weight per week.
How Much Tuna Can You Eat?
Basically, it depends on your body weight and the exact brand of tuna you buy, but generally you could eat anywhere between 25 and 35 small cans of tuna a week before you would hit your maximum mercury limits.
That’s a level even the most keen tuna-lover would be hard pressed to consume. However, there is a cumulative effect, and some studies show that it takes more than 18 years for mercury to be released from your body. So, moderation would be recommended.
Symptoms Of Mercury Poisoning
When it comes to symptoms of mercury poisoning, early detection and treatment is crucial. Early diagnosis improves the chances of recovery and minimizes neurological effects. Symptoms of mercury poisoning include blindness, incoherent speech, and tremors. Delays in diagnosis and treatment can lead to profound neurological impairment and residual signs.
Avoiding Mercury During Pregnancy
Pregnant women are advised to limit their fish intake because of placental transfer of mercury to the unborn foetus and the effect of mercury on neural development.
Pregnancy is a crucial time for pregnant women to reduce their consumption of mercury by eating fish with low mercury levels. During pregnancy, breast milk can contain traces of mercury. To protect the unborn child from mercury poisoning, pregnant women should limit their consumption of fish during pregnancy and breastfeeding.
Recommended Books:
The Harvard Medical School Guide to Tai Chi: 12 Weeks to a Healthy Body, Strong Heart, and Sharp Mind -- by Peter Wayne.
Cutting-edge research from Harvard Medical School supports the long-standing claims that Tai Chi has a beneficial impact on the health of the heart, bones, nerves and muscles, immune system, and the mind. Dr. Peter M. Wayne, a longtime Tai Chi teacher and a researcher at Harvard Medical School, developed and tested protocols similar to the simplified program he includes in this book, which is suited to people of all ages, and can be done in just a few minutes a day.
Click here for more info and/or to order this book on Amazon.
Browsing Nature's Aisles: A Year of Foraging for Wild Food in the Suburbs
by Wendy and Eric Brown.
As part of their commitment to self-reliance and resiliency, Wendy and Eric Brown decided to spend a year incorporating wild foods as a regular part of their diet. With information on collecting, preparing, and preserving easily identifiable wild edibles found in most suburban landscapes, this unique and inspiring guide is a must-read for anyone who wants to enhance their family's food security by availing themselves of the cornucopia on their doorstep.
Click here for more info and/or to order this book on Amazon.
Food Inc.: A Participant Guide: How Industrial Food is Making Us Sicker, Fatter, and Poorer-And What You Can Do About It -- edited by Karl Weber.
Where has my food come from, and who has processed it? What are the giant agribusinesses and what stake do they have in maintaining the status quo of food production and consumption? How can I feed my family healthy foods affordably? Expanding on the film’s themes, the book Food, Inc. will answer those questions through a series of challenging essays by leading experts and thinkers. This book will encourage those inspired by the film to learn more about the issues, and act to change the world.
Click here for more info and/or to order this book on Amazon.
