What to Avoid When Eating Crab: A Guide to Proper Nutrition and Diet

October 23, 2025 •

5 min read

While crab meat is a nutritious source of protein and omega-3 fatty acids, improper preparation or consumption can lead to foodborne illness or other health issues. Knowing what to avoid when eating crab is crucial for a safe and healthy dining experience, protecting you from toxins, bacteria, and allergens.

Quick Summary

This guide explains which parts of a crab to discard, the risks of consuming raw or undercooked shellfish, and how to minimize exposure to accumulated toxins. It also covers common allergens, the dangers of adding excessive sodium, and outlines essential safety practices for preparing and eating crab.

Key Points

Discard the Guts: Always remove and discard the gills ("dead man's fingers") and the tomalley ("crab fat") to avoid toxins and heavy metals.
Cook Thoroughly: Never eat raw or undercooked crab, which can harbor dangerous bacteria and parasites that are only killed with proper heat.
Watch the Sodium: Be mindful of crab's natural salt content and avoid adding high-sodium sauces and seasonings, especially if you have hypertension.
Know Your Allergies: Shellfish allergies are common and can be severe; individuals with sensitivities must avoid crab entirely due to proteins like tropomyosin.
Use Fresh, Live Crab: Select live, active crabs with firm shells for the best flavor and safety, and store them correctly before cooking.
Discard Cooking Liquid: After boiling or steaming whole crabs, always throw out the cooking liquid to prevent re-absorbing leached toxins.
Be Mindful of Health Conditions: Those with gout, kidney disease, or hypertension should consult a doctor before consuming crab due to its purine and sodium content.

Toxic and Indigestible Crab Parts to Discard

Crab is a culinary delight, but not every part is meant for consumption. Discarding certain internal organs is crucial for both safety and taste. When cleaning a cooked crab, you will encounter parts that should be removed and discarded, regardless of how thoroughly the crab was cooked.

The 'Dead Man's Fingers' (Gills)

One of the most widely known parts to avoid is the gills, also colloquially known as "dead man's fingers" or "devil's fingers". These feathery, gray, or white cones line the outer edges of the crab's body cavity. While not inherently toxic, they are tough, chewy, and have an unpleasantly bitter taste. Removing them is a standard part of preparing a crab and improves the eating experience significantly.

Viscera and Tomalley (Crab Fat)

Inside the crab's body cavity, you will find the viscera, which includes the digestive organs and the hepatopancreas, a substance often called "crab fat," "crab mustard," or "tomalley". This rich, golden-yellow or green substance is considered a delicacy by some, but health advisories consistently recommend against eating it. The tomalley is where environmental toxins, heavy metals, and pollutants, such as PCBs and domoic acid, can accumulate. If the crabs come from areas with known contamination, avoiding the tomalley is a critical safety precaution. Additionally, any liquid used to cook whole crabs should be discarded and not used for sauces or soups, as toxins from the viscera can leach into it.

Food Safety Hazards: Undercooked and Raw Crab

Proper cooking is the most effective way to neutralize bacteria and parasites that may be present in crab and other shellfish.

The Dangers of Raw Shellfish

Raw or undercooked crab can harbor dangerous microorganisms, including bacteria like Vibrio parahaemolyticus and parasites such as lung fluke (Paragonimus westermani). Infections from these pathogens can cause severe gastrointestinal issues, while lung flukes can cause serious lung and neurological diseases. Cooking methods involving marination with ingredients like vinegar or alcohol are not sufficient to kill these harmful organisms.

Proper Cooking is Key

To ensure crab is safe to eat, it must be cooked thoroughly to an internal temperature of at least 165°F (75°C). The best method for cooking crab is steaming, as it maintains the meat's delicate flavor and texture, preventing it from becoming waterlogged. Overcooking, especially through boiling, can result in tough, rubbery meat.

Hidden Health Risks: Allergies, Toxins, and Sodium

Beyond the obvious pitfalls of undercooked food, several other factors can affect your health when eating crab.

Shellfish Allergies

Shellfish is one of the most common food allergens, with reactions ranging from mild rashes and itching to severe, life-threatening anaphylactic shock. The primary allergen is tropomyosin, a protein that can cause cross-reactivity with other crustaceans and even house dust mites. Individuals with a confirmed shellfish allergy must avoid crab entirely.

Environmental Toxins

Natural toxins, like domoic acid produced by certain algae during "red tide" blooms, can accumulate in crab viscera. Symptoms of domoic acid poisoning can be severe, including gastrointestinal and neurological problems. Environmental pollutants like polychlorinated biphenyls (PCBs) and dioxins can also concentrate in the tomalley and pose long-term health risks if consumed frequently.

Beware of Excess Sodium

Crab meat naturally contains sodium, and many prepared versions are frozen in a salt brine, increasing their salt content. Adding high-sodium seasonings or sauces, such as soy sauce, certain seafood blends, or seasoned salt, can lead to excessive sodium intake. Individuals with hypertension, kidney disease, or other salt-sensitive conditions should be particularly careful. Flavor alternatives like lemon, herbs, and garlic can provide taste without the added sodium.

Incompatible Food Pairings

Some traditional or unverified sources suggest avoiding certain food pairings with seafood. For example, some traditions suggest avoiding fruits high in vitamin C with seafood, citing a myth about arsenic, which is not supported by scientific evidence for modern food practices. However, people with gout should be cautious with high-purine seafood, and consuming it with alcohol can exacerbate the risk.

A Healthier Crab Dining Experience: What to Do

To maximize the health benefits and minimize risks, follow these best practices:

Choose Wisely: Buy live, active crabs with firm, unworn shells from a reputable supplier.
Handle Carefully: Store live crabs in a cool, moist place before cooking. Wash your hands and all surfaces that come into contact with raw seafood.
Prepare Correctly: Clean the crab by removing the gills and viscera before cooking. This is especially important for whole crabs.
Cook Thoroughly: Ensure the crab is fully cooked to a bright red color, with firm, opaque meat, and an internal temperature of 165°F (75°C).
Season Smartly: Opt for low-sodium alternatives like lemon juice, garlic, and fresh herbs to enhance flavor without adding salt.

Serve Responsibly: Discard all cooking liquid from steamed or boiled crabs and never reuse it for sauces or stews.

Comparison Table: Safe vs. Unsafe Crab Consumption


Aspect	What to Avoid	Best Practices
Internal Organs	Eating the gills (dead man's fingers) or tomalley (crab fat)	Discarding the feathery gills and the central viscera completely
Cooking Method	Marinating raw crab or eating it undercooked	Thoroughly steaming, boiling, or grilling until meat is opaque and reaches 165°F (75°C)
Seasonings	Adding excessive salt, soy sauce, or other high-sodium seasonings	Using fresh herbs, garlic, black pepper, and lemon juice to season
Crab Condition	Buying or consuming dead, sluggish, or slimy crabs	Opting for fresh, live crabs that are active and feel heavy for their size
Cooking Liquid	Reusing the liquid from boiling or steaming whole crabs for sauces	Discarding all cooking liquid to prevent reabsorption of toxins
Health Risks	Ignoring shellfish allergies and high-sodium intake	Consulting a doctor if you have allergies or conditions like hypertension or gout

Conclusion

While crab can be a delicious and healthy part of your diet, enjoying it safely requires care and awareness. The most critical steps involve discarding the toxic and indigestible parts, such as the gills and tomalley, and ensuring the crab is cooked thoroughly to eliminate harmful bacteria and parasites. For individuals with health concerns like allergies, hypertension, or gout, being particularly cautious with consumption and seasoning is essential. By following these guidelines, you can savor the sweet, tender meat of a crab while minimizing potential health risks and ensuring a safe, nutritious dining experience. For more information on food safety and preparing seafood, consider reviewing guidelines from authoritative sources, such as the U.S. Food and Drug Administration (FDA).

U.S. Food and Drug Administration (FDA) on Seafood Safety

Frequently Asked Questions

The gills, or "dead man's fingers," are feathery, cone-shaped parts that line the crab's body cavity. They are not toxic, but they are tough, indigestible, and taste bitter, which is why they are typically discarded when cleaning a crab.

Health officials advise against eating the tomalley. This yellowish-green substance is the crab's digestive gland, and it can accumulate environmental pollutants like PCBs, dioxins, and potentially harmful toxins like domoic acid. It's safest to discard it completely.

Yes, you can get food poisoning from eating crab, particularly if it's undercooked or raw. Crabs can carry bacteria like Vibrio or parasites like lung fluke that can cause severe illness if not killed by proper cooking. Symptoms can include abdominal pain, nausea, and vomiting.

When cooked, a crab's shell will turn a vibrant reddish-orange, and its meat will be opaque and firm. To be certain, use a food thermometer to check that the internal temperature reaches at least 165°F (75°C).

Yes, people with high blood pressure should be cautious. Crab meat contains natural sodium, and commercially prepared or frozen crab is often brined, further increasing its saltiness. It is important to avoid adding extra salt or high-sodium sauces.

Pregnant women should be cautious. While crab is generally low in mercury compared to many fish, there's a risk of foodborne illness from undercooked shellfish. Additionally, some traditional medicine views suggest pregnant women should limit or avoid crab, though this is not a universal medical recommendation.

You should always discard the cooking liquid. When cooking whole crabs, toxins and chemicals from the viscera can leach into the water. Reusing this liquid for sauces or soups can concentrate these harmful substances.