Seafood is a great source of nutrients like protein, omega-3 fatty acids, iron, zinc, and iodine. However, some seafood may contain high levels of methylmercury, a compound that can have a negative impact on the nervous system. For this reason, it is important to know about the different types of low-mercury seafood in the Philippines.

How does mercury reach our seafood?

Before we explain why you should eat low-mercury seafood, we first need to understand where the harmful mercury compound comes from.

Mercury occurs naturally in our environment. For instance, it can be released into the air during volcanic activity. But mercury can also come from human action. We produce mercury through the burning of coal and fossil fuel and the disposal of household or industrial wastes. The mercury eventually settles into the sediments in bodies of water, such as lakes, seas, and oceans. There, bacterial activity converts the inorganic mercury (mercury that hasn’t combined with carbon) to methylmercury (the one that has already combined with carbon).

Sea creatures absorb methylmercury in two ways. They absorb it when water passes through their gills or they eat other fish that have mercury. Like fish, humans can ingest methylmercury through the food.

What are the dangers of eating high-mercury fish and seafood?

The dangers of eating high-mercury fish and seafood often depends on several factors:

• The type of mercury (inorganic, methyl mercury, etc.)
• Dosage and duration of exposure
• Our age (or developmental stage, in the case of fetuses)

According to the World Health Organization (WHO), we have all been exposed to mercury in one way or another. Majority of us have had long-term exposure to low levels of mercury, while others experience constant exposure to high levels of mercury. The people who are most vulnerable to the effects of methylmercury are those who rely primarily on seafood for their sustenance.

If you are experiencing any of the symptoms below, seek medical help right away. They could be the symptoms of mercury poisoning:

• Loss of peripheral vision or blindness
• Cerebral palsy
• The feeling of pins and needles around the mouth, hands, and feet
• Impaired hearing and speech
• Difficulty walking and muscle weakness

Another high-risk group is that of fetuses and children under 6 years of age. If a pregnant mother consumes high-mercury seafood, the compound may reach the baby’s system. When that happens, the methylmercury negatively affects the baby’s developing brain and nervous system. Additionally, some reports indicate that mercury exposure can damage the fetus’ heart and blood vessels.

After the birth of a baby that has been exposed to high levels of mercury, parents may notice health problems like:

• Microcephaly (small head)
• Developmental delay and/or intellectual disability
• Seizures
• Blindness

Very young kids who consume high-mercury fish and seafood can also suffer from the health conditions mentioned above.

How much is too much mercury?

You must be wondering: what levels of mercury might cause harm? Unfortunately, this question is tricky due to the fact that there are very few studies that focus on extracting measurements.

For now, scientists have determined that the benchmark dose of methylmercury that results in non-lethal effects (such as changes in the nervous system) in fetuses is 58 micrograms of methylmercury per liter of cord blood (blood that remains in the placenta). On the other hand, adults and children can start experiencing the adverse effects of mercury consumption at quantities of less than 3 micrograms per kilogram of body weight.

Since it is difficult to determine the amount of mercury we consume through food, the best course of action is to identify the high-mercury and low-mercury seafood in the Philippines.

Low-mercury seafood in the Philippines

Now that you know the dangers of ingesting dangerous amounts of mercury, let’s talk about the low-mercury seafood here in the Philippines. According to medical experts, the following are the types of seafood with the lowest mercury levels:

• Anchovies (dilis)
• Catfish (hito)
• Clams (halaan)
• Cod (bakalaw)
• Crab (alimasag)
• Mackerel (galungong)
• Oysters (talaba)
• Tilapia and salmon
• Sardines (sardinas)
• Scallops
• Shrimp (hipon)
• Squid (pusit)

The following also have low mercury levels:

• Albacore, white and yellowfin tuna
• Seatrout
• Mullet (Banak)
• Herring (Tamban)
• Red snapper (Maya-maya)

Please note that children and adults, including pregnant and breastfeeding mothers, can have 2 to 3 weekly servings of the low-mercury seafood in the first list. However, they can have only 1 serving per week of seafood in the second list.

Keep in mind that while children and adults have the same number of recommended servings, the serving sizes vary. For adults, 1 serving is equal to 113 grams or 4 ounces. For kids 2 to 10 years old, 1 serving is equal to 28 grams or 1 ounce.

High-mercury fish and seafood

After learning about low-mercury seafood here in the Philippines, let’s talk about the seafood to avoid because they can contain high levels of methylmercury:

• Fresh tuna or sashimi
• Sea bass (apahap)
• Grouper (lapu-lapu)
• Swordfish, blue marlin, and shark
• Tilefish (matang dagat)

Key takeaways

Seafood is a healthy and lean protein. However, some types of seafood may be toxic due to high methylmercury content. People therefore can have 1 to 3 servings of low-mercury seafood per week. Meanwhile, high-mercury seafood should be avoided, especially by pregnant women and children.

Learn more about Healthy Eating here.