Shocked by Safe Limits: Tinned Food Caused Deadly Poisoning

The Hidden Dangers of Excessive Tuna Consumption

A 29-year-old office worker from Alabama, USA, has shared her harrowing experience of developing life-threatening mercury poisoning after consuming tuna three times a day for several months. Nasha Montgomery’s story highlights the potential risks of overindulging in what many consider a healthy food choice.

Montgomery spent four months at the end of 2021 preparing large batches of tuna salads, believing she was making a nutritious decision. Her daily routine included eating tuna with crackers for breakfast, in sandwiches for lunch, and as a snack at work. This habit led her to consume approximately six tins of tuna per week, or around 1.5kg in total.

After a few months, she began experiencing symptoms such as muscle cramps, tingling in her hands and feet, and a metallic taste in her mouth. Initially, she attributed these issues to stress from her new job in office management. A routine blood test came back normal, which further convinced her that the symptoms were not serious.

However, when her condition did not improve, she returned to the doctor, who asked if she had been consuming any particular type of food in large quantities. She mentioned tuna, and a more detailed blood test revealed high levels of mercury in her system. Doctors diagnosed her with suspected mercury poisoning, a condition that occurs when toxic metals accumulate in the body, leading to symptoms like memory problems, numbness, tremors, and in severe cases, permanent brain and kidney damage.

Fish such as shark, swordfish, tuna, and king mackerel are known to contain high levels of mercury. Studies indicate that consuming more than 25 tins of tuna per week or around 16 tuna steaks can pose a risk of mercury poisoning. However, certain types of tuna, like albacore, have higher mercury content. Pregnant women or those planning to become pregnant should limit their intake to no more than two cans of tuna or two tuna steaks per week due to the risk of mercury exposure to the baby.

Montgomery expressed her shock at the diagnosis, stating that she believed she was making a healthy choice by eating tuna. “I thought I was doing something right by eating the tuna,” she said. “It was healthy, and the things I was eating the tuna with were also healthy. I felt like I was doing right by myself, but too much of a good thing can always backfire.”

Doctors advised her to eliminate tuna from her diet for six to eight months until all symptoms subsided. “I basically had to detox from tuna. I was detoxing like I was addicted to it,” she explained. Although she still experiences occasional tingling or numbness in her fingers and feet, she has not suffered any long-term effects.

Treatment for mercury poisoning typically involves stopping exposure to the metal. In some cases, chelation therapy is used, where a machine removes metals from the body through an IV drip. Other options include dialysis or surgery to physically remove mercury from the body, depending on how the individual was exposed.

Mercury enters fish through a buildup in the ocean, primarily due to activities like mining and burning coal. In the UK, the maximum allowed level of mercury in tuna products is 1.0g/kg. However, a study by Foodwatch and Bloom found that 148 cans of tuna from five European countries tested positive for mercury, with one tin in Paris containing 3.9 mg/kg—13 times the legal limit of 0.3 mg/kg.

Bloom and Foodwatch urged European nations to activate a safeguard clause to prevent the sale of products exceeding the mercury limit and to remove tuna from school canteens, nurseries, maternity wards, hospitals, and care homes. However, the UK Food Standards Agency stated that only one out of 30 products tested in the UK market exceeded the legal limit, emphasizing that they had not seen the detailed results of the study.

Montgomery’s experience serves as a cautionary tale about the importance of moderation, even with foods considered healthy. It also underscores the need for awareness and vigilance regarding mercury levels in commonly consumed seafood.