The Truth About Seafood (Especially Bivalves): What You Need to Know

Seafood, including bivalves like clams, oysters, mussels, and scallops, is often praised for its nutritional benefits, especially its omega-3 fatty acids and zinc. However, there’s another side to the story—one that involves serious risks from environmental toxins, harmful pathogens, and potential links to neurodegenerative diseases like ALS. Understanding these risks can help you make informed choices about your diet.

Seafood Is a Major Source of Environmental Toxins

Many pollutants found in our oceans accumulate in seafood, especially in fatty fish and long-lived marine animals. These toxins include:

• Organochlorine pesticides (like DDT)
• PCBs (industrial chemicals linked to cancer and immune dysfunction)
• PFAS (so-called “forever chemicals” that disrupt hormones and metabolism)
• Methylmercury (a neurotoxin that affects brain function)^1-6

Since bivalves are filter feeders, they absorb pollutants directly from their environment, making them a concentrated source of microplastics and toxins. While they may have lower mercury levels than some fish,^7,8 their long lifespan allows them to accumulate other harmful substances over time.⁹ 

Microplastics: A Hidden Threat in Bivalves

The plastic waste accumulating in our oceans degrades into microplastics and pollutes sea life. The plastic pollution crisis isn’t just an environmental issue—it’s a health concern, too. Microplastics, which come from degraded plastic waste, have been found in commercial bivalves worldwide. Research suggest these tiny plastic particles cause inflammation, genotoxicity, and neurotoxicity in these species. 
Exposure to microplastics in humans could lead to endocrine disruption, inflammation, increased exposure to pollutants, and other health hazards.^9-11 Since bivalves have a long lifespan naturally filter large amounts of water, they absorb more microplastics than many other seafood sources.⁹ When you eat bivalves, you’re likely ingesting these harmful particles, too.

Bivalves and Foodborne Illness: A Risky Combination

Bivalves are particularly susceptible to bacterial and parasitic infections because they filter feed directly from their surroundings. Some of the most concerning pathogens found in bivalves include:

• Vibrio bacteria, which can cause severe gastrointestinal illness, bloodstream infections, and in extreme cases, limb amputation.¹²
• Blastocystis parasites, which can cause intense abdominal pain and gastrointestinal distress.¹³
• Toxic algae bloom-related compounds, which can cause neurological, respiratory, and digestive symptoms.

Toxins that originate in cyanobacteria (often called “blue-green algae,” even though they are not algae) and other small organisms that cause algal blooms in bodies of fresh or salt water are an especially serious concern, many are neurotoxins that could lead to serious health issues.^14,15 

The Connection Between Bivalves and Neurodegenerative Disease

One of the most alarming concerns about bivalve consumption is the potential link between cyanobacteria-derived toxins and neurodegenerative diseases like amyotrophic lateral sclerosis (ALS). Research has identified a neurotoxic compound called BMAA, which is produced by cyanobacteria and found in some contaminated seafood.

Studies have linked BMAA exposure to increased rates of ALS and other neurodegenerative conditions. For example:

• A Guam-based study found that local populations exposed to BMAA had ALS-like disease rates 100 times higher than the global average.¹⁶
• A New Hampshire study identified a cluster of ALS cases 25 times higher than usual in an area known for cyanobacterial blooms.¹⁷
• Research suggests that BMAA can replace a natural amino acid in the body, which could lead to protein dysfunction, toxic protein build-up, and neurological damage.¹⁸

To make matters worse, BMAA appears to work synergistically with mercury, amplifying its toxic effects on the nervous system.¹⁹

It’s also important to note that cooking does not eliminate algal bloom toxins such as BMAA.¹⁵

Is Seafood the Only Source of Omega-3s? Absolutely Not!

One of the biggest reasons people continue to eat seafood is its omega-3 content, particularly DHA and EPA—two important fatty acids that help maintain brain function with aging and a healthy mood state. While it’s true that plant-based omega-3s (ALA from flax, chia, and walnuts) don’t convert efficiently into DHA and EPA,^20-23 there’s a better, safer solution than eating fish: algae-based DHA & EPA supplements.

Related: Want to live longer? Watch your omega-3 levels

Dr. Fuhrman’s DHA & EPA Purity is an excellent choice because:

• It comes from algae, not fish, making it completely fish-free
• The algae are grown in a clean lab environment, not harvested from the ocean
• It provides a reliable source of pre-formed DHA and EPA, important for optimal brain function
• It’s a more sustainable, eco-friendly alternative to fish oil
• Unlike other products with oxidation and rancidity, our unique formulation is packed in dark glass and kept refrigerated until it's shipped to maintain freshness

Unlike bivalves and other seafood, algae-derived omega-3s deliver the same health benefits without the risks associated with mercury contamination, microplastics from ocean pollution, or cyanobacteria-derived neurotoxins in seafood.

Bottom Line: Avoid Seafood for Better Health

Given the overwhelming evidence, avoiding bivalves and other seafood is a smart and precautionary choice. The risks—from pollutants and foodborne pathogens to neurotoxins linked to ALS—far outweigh the potential benefits. Fortunately, you don’t need seafood to get essential nutrients like omega-3s and zinc. With smart supplementation and a nutrient-rich plant-based diet, you can nourish your body safely and effectively.