Mercury and fish – what are the risks?

Checking in on our health is so important. So many of the common conditions which go on to be serious and debilitating, if caught early, are easily managed through diet or lifestyle changes. And being aware of the different risks at every age can help you know what to be on the lookout for. 

With many of us making a conscious decision to eat less red meat, fish is featuring more on our plates as a healthy alternative source of protein, micronutrients, and good fats.

But while fish may seem like a bit of a wonder food, there are concerns that increased levels of toxic mercury found in some types of fish could be putting our health at risk.

So, what should we be on the lookout for?

What’s the problem with mercury?

Mercury is a heavy metal found naturally in air, water, and soil. It’s released into the environment in several ways, including through industrial processes like burning coal or natural events like eruptions.

There are three main forms of mercury: elemental, inorganic, and organic

People can be exposed to this toxin in a number of ways, such as breathing in mercury vapours during mining and industrial work, or by eating fish and shellfish which absorb low concentrations of mercury through water pollution.

Over time, the organic form of mercury, which is highly toxic, can concentrate in the body, causing serious health problems.

Levels of mercury in fish

The amount of mercury in fish and other seafood depends on the species and the levels of pollution in its environment.

Overall, larger, and longer-lived fish tend to contain the most mercury. These include shark, swordfish, fresh tuna, marlin, and king mackerel. Larger fish tend to eat many smaller fish, which contain small amounts of mercury, leading to an accumulation over time.

What impact can this have on health?

Exposure to mercury can cause serious health problems. In both humans and animals, higher levels of mercury are associated with brain problems.

A study in 129 Brazilian adults found that higher levels of mercury in hair were associated with a decrease in fine motor skills, dexterity, memory, and attention. Recent studies also link exposure to heavy metals such as mercury to conditions like Alzheimer’s, Parkinson’s, autism, depression, and anxiety. Additionally, mercury exposure is linked to high blood pressure, increased risk of heart attacks, and higher LDL cholesterol.

Mercury in fish does not affect everyone in the same way and some people should take extra care. Those at risk include pregnant women, breastfeeding mothers, and young children.

So, should you keep eating fish?

This information might seem scary but realistically, the benefits of eating fish do tend to outweigh the risks.

Fish are an important source of omega-3 fatty acids and provide multiple other benefits. In fact, it is generally recommended that most people eat at least two servings of fish per week.

However, it’s recommended that people at high risk of mercury toxicity, such as pregnant or breastfeeding women keep a few things in mind:

• Eat 2–3 servings of a variety of fish every week.
• Choose lower-mercury fish and seafood, such as salmon, shrimp, cod, and sardines.
• Avoid higher-mercury fish, such as shark, swordfish, and king mackerel.