Are Crab Legs a Healthy Food?

Crabs are a common shellfish used in sushi, tacos, soups, stews and many other foods. If you're a fan of fresh crab, you'll often find it steamed, grilled or boiled whole. The legs and claws are considered among the most succulent parts of this crustacean. Like other shellfish, crabs are considered nutritious because they're full of vitamins, minerals and healthy fats.

Read more: 9 Excuses to Eat More Seafood (Hint: It Can Make You Happy!)

Many varieties of crabs are eaten around the world. This means that saying that you like to eat crab is a bit like saying that you like to eat birds. There are so many different types of crabs that comparing them can be like comparing turkeys to quails.

You can find tiny, fried, soft-shelled crabs half the size of your palm sold on the streets of Vietnam. On the other end of the spectrum, you have giant, carnivorous spider crabs and coconut crabs as large as a person. Although coconut crabs are the largest arthropods, Japanese spider crabs have legs that can reach up to 13 feet in length.

The crabs you'll find commonly sold in supermarkets are usually no more than a few hundred grams in size. Popularly consumed crabs include:

• Alaskan king crabs
• Blue crabs
• Dungeness crabs
• Queen crabs
• Snow crabs
• Stone crabs
• Soft shell crabs
• Spider crabs
• Horsehair crabs

Anyone who likes eating meat or fish knows that bones carry a lot of flavor. Crabs and other shellfish don't have bones like fish or animals. Instead, they have exoskeletons, which are their hard outer shells.

Crab legs, which are typically cooked whole, have a lot of shell compared to the amount of meat they contain. This is a positive, though — meat from a crab's legs and claws can be more flavorful than the rest of the crab.

Every type of crab has slightly different nutritional values, but most are rich in the same vitamins and minerals. There are also typically no carbohydrates and few calories in crabs legs. For example, 100 grams of Alaskan king crab helps you get closer to your daily needs, providing:

• 5 percent of the daily value (DV) for calcium
• 131 percent of the DV for copper
• 15 percent of the DV for magnesium
• 22 percent of the DV for phosphorus
• 6 percent of the DV for potassium
• 73 percent of the DV for selenium
• 69 percent of the DV for zinc

One hundred grams of Alaskan king crab also helps you meet your daily vitamin needs, for example:

• 8 percent of the DV for vitamin B3 (niacin)
• 8 percent of the DV for vitamin B5 (pantothenic acid)
• 11 percent of the DV for vitamin B6
• 13 percent of the DV for vitamin B9 (folate)
• 479 percent of the DV for vitamin B12
• 8 percent of the DV for vitamin C

Crabs are also rich in omega-3 fatty acids and protein. The protein in crab legs can range between 35 and 39 percent of the DV per 100 grams, depending on the crab. One hundred grams of Alaskan king crab is on the upper end of this range, with 39 percent of the DV for protein. Some crabs, like the blue crab, also contain other nutrients, like choline and vitamin E.

There aren't any major nutritional differences between a crab's legs and its body. Leg size differs widely, though — and Alaskan king crabs have much larger legs than those of most other crabs. You might find also that the meat inside the crab's body is a bit flakier than that of the legs.

Read more: 7 Reasons to Consider a Pescatarian Diet

Crabs are one of the healthiest types of shellfish you can consume. Although they are often fairly expensive, the array of nutrients in small servings makes them worthwhile foods to eat. Omega-3 fatty acids, which are essential polyunsaturated fats typically found in marine products, are one of the best nutritional aspects of crab.

Omega-3 fatty acids are very important for your health. Too little of these healthy fats can cause skin problems. In contrast, their consumption can reduce the rate of cardiovascular, neurological, inflammatory and eye diseases.

Large amounts of omega-3 fatty acids are usually found in fatty fish, like salmon and mackerel. However, these healthy fats are so important that they are even being added into the feed of farmed populations of crabs. This increases the amount of these healthy fats in their bodies, improving their health and also their nutritional value.

Crabs are great sources of a variety of different vitamins and minerals. However, it's possible to have too much of a good thing. Since crabs are so nutritious, any side effects of eating crab are likely related to excessive consumption of certain nutrients.

With 131 percent of the DV for copper and 479 percent of the DV for vitamin B12 in just 100 grams of Alaskan king crab, it's easy to see how this can occur. Vitamin B12 is a water-soluble vitamin — which means that it's safe to consume in even large amounts. However, it's possible to consume too much copper. Too much of this mineral can cause gastrointestinal problems like diarrhea and vomiting, while long-term buildup of copper in your body can even cause organ failure.

Of course, not all crabs have the same nutrition — which is good, as this allows you to still consume crab while varying the nutrients you're ingesting. Both Dungeness and queen crabs have much less copper, with 75 and 63 percent of the DV per 100 grams, respectively. Alaskan king crabs are also very rich in zinc, with 69 percent of the DV per 100 grams. Both Dungeness and blue crabs have about half that amount: 39 and 35 percent of the DV, respectively.

If you don't eat crabs very often, their nutrient content likely isn't an issue. In fact, it's probably a good thing! If you're eating crabs every day or every week, though, be careful you're not consuming too much of certain nutrients.