Shell to the No!

Shell to the no!

As a Christian Dietitian, I am baffled when I read about the dietary laws of the Old Testament. It was as if God was revealing His complex understanding of pathology, biology, and ecology, to a people that didn't even have access to microscopes. Now that we do, we can look back at these laws through science and see just how wise God’s dietary regulations were. 

Let's look at what God had to say about fish thousands of years ago, and compare it to what science has to say about it today. 

Biblical Dietary Regulations Regarding Fish

First off, I want to start by pointing out that God decreed that his children were not to eat raw meat, no matter what type of meat!

Leviticus 17:14 “For [it is] the life of all flesh; the blood of it [is] for the life thereof: therefore I said unto the children of Israel, Ye shall eat the blood of no manner of flesh: for the life of all flesh [is] the blood thereof: whosoever eateth it shall be cut off”

Just wanted to get that out of the way! Sorry Sushi!

We then read  specific rules as to what type or manner of fish could be consumed in Leviticus 11: 9-10

v.s. 9 “These shall ye eat of all that are in the waters: whatsoever hath fins and scales in the waters, in the seas, and in the rivers, them shall ye eat”

“v.s. 10. And all that have not fins and scales in the seas, and in the rivers, of all that move in the waters, and of any living thing which is in the waters, they shall be an abomination unto you:”


Yup, that's right, for all my ladies and gents in the south, the Israelites did not have the privilege of enjoying low country boils full of shellfish like crabs, shrimp, oysters, clams etc. Nor did they enjoy catfish! But for good reason! 

First, let's think about fish that have fins and scales versus those that don’t. 

Take a lobster or a clam for example. Have you ever noticed how little and how slowly they move? Now let's think of a finned and scaled fish like salmon . Salmon are constantly swimming through the water, and their scales definitely help them with this. Most species can even travel over 40 miles in a day when they are migrating. This means that they are able to have access to fresher water easier and it also helps with the mobility of their digestive system. 

You may already see where I am going with this argument, but let's look into shellfish a little deeper. 

So, What Happens When You Eat the Oceans Air Filter?

Many crustaceans and mollusks are referred to as the filters of the sea. Their job is to help the ocean by filtering pathogens and other debris from the water, some are even tasked with the decomposition of dead bodies. Not to mention, many crustaceans and parasites have a symbiotic relationship which help them both do their job even better.

Just think about what happens when waters get contaminated with human sewage, or other contaminants, who do you think is voluntold to clean them up? It is indeed these so called filters of the sea. They do what they are created to do, and they do it well!

For that reason, crustaceans and mollusks are known to harbor several viruses, bacteria and parasites, more so than some of their larger finned fish counter parts.

In fact,  a study conducted in the US looking at foodborne illness from seafood from the year 1973-2006 found that 61% of illnesses were from shelled fish such as mollusks (predominantly oysters)and crustaceans (predominantly crab and shrimp)[1]. Most of these outbreaks occurred during the summer months! So, my local Floridians, make sure you are careful when you eat local seafood this summer!

Bivalve mollusks such as clams, oysters, and scallops are notorious for carrying pathogens such as salmonella, E. coli, vibriosis, marine biotoxins like diuretic shellfish poisoning and viruses such as  hepatitis A! All of which can result in one or several of the following symptoms: vomiting, diarrhea, and abdominal pain[1,2]. Please never eat these bivalves raw!

The scary part is that some infections like hepatitis A can take 2 to 8 weeks for symptoms to present due to the viruses’ incubation period, making food induced infections very hard to track. To make matters even worse, hepatitis A and other vibrio can be fairly heat resistant [3].

In fact, biotoxins are rarely ever destroyed by heat, while vibrio require heavy steaming, or boiling to be killed.[3].

However, many people eat oysters raw, steam shrimp just until they turn pink, or steam clams, and scallops just until they begin to open, this can make it very easy for bacteria and viruses to stay intact.  

Personally, some of the worst  experiences I have had from contracting food borne illnesses were from oysters, clams, and shrimp in  that order! I grew up eating dishes like low country boils, and they still remain a family favorite, but I can tell you that as  for me, I rarely consume them and when I do, I try to make sure they are cooked thoroughly. 

Would You like Some Plastic With That? 

Again, think of all the toxins that are dumped into the ocean every year, such as biproducts from various industries. Oil, plastics, sewage, heavy metals, the list goes on! Yeah, those make it into our seafood too. In fact, a lot of research is emerging in particular about the microplastic content found in shellfish, and their long term implications for health . 

One study in particular estimated that top shellfish consumers in Europe ingest approximately 11,000 Microplastic particles a year[4] ! Yikes. These filters of the sea, fortunately, but unfortunately continue to come running to the oceans rescue, trying to clean up the mess that humanity created. 

And the correlation between frequent consumption of these plastics and other contaminants on the potential risk for heart disease, gastrointestinal disorders, and reproductive disorders is not looking very pretty folks! In fact, it's so not pretty, that I am going to be doing separate posts on these topics so that you can be informed and equipped regarding how to limit such contaminants  in our food chain! 

Nutrition Composition:

I would also be remiss if I didn't note that finned fish typically have a healthier fat profile than non-finned fish when it comes to omega 3s! These powerful inflammation fighting fats are higher in fish like salmon, and sardines. Omega 3 intake is also very low in most diets, so aiming to have seafood that rich in these fats are important.

However, I will say that shellfish still have benefits to overall health. They have an impressive micronutrient content, and are low in saturated fat which is a big plus, since saturated fat is something we really need to keep our eye on when it comes to our individual cholesterol levels! Stay tuned, because I want get into the cholesterol and saturated fat discussion on another post.

Before we rap this up, I know what else you may be thinking, in this modern age, it is not just shellfish we have to be concerned about when it comes to pollutants, especially trace metals like mercury. You are absolutely right.

Again, you better stay tuned, because we will be addressing a lot of these topics soon!

Overall, it's no surprise that shellfish were a big no no for the Israelites. 
God knew these creatures  had an important job to do when it came to marine ecology that could inadvertently result in negative effects to us when we ate them.  Perhaps with our current environmental climate, it's best we keep shellfish in the water.

Praise God that  foods are no longer considered morally unclean thanks to Jesus Christ! However, I think it is wise to take heed with shellfish. Be sure to check out the CDC's website for tips on preventing food-borne illnesses from seafood. 

Thanks for joining me today. In the meantime, try your best to Eat Wisely, the Way God Intended!


  1. Iwamoto M, Ayers T, Mahon BE, Swerdlow DL. Epidemiology of seafood-associated infections in the United States. Clin Microbiol Rev. 2010 Apr;23(2):399-411.
  1. Ristori CA, Iaria ST, Gelli DS, Rivera IN. Pathogenic bacteria associated with oysters (Crassostrea brasiliana) and estuarine water along the south coast of Brazil. Int J Environ Health Res. 2007 Aug;17(4):259-69.
  2. Marine Biotoxins. Washington State Department of Health.
  3. Smith M, Love DC, Rochman CM, Neff RA. Microplastics in Seafood and the Implications for Human Health. Curr Environ Health Rep. 2018 Sep;5(3):375-386.
Written by
Ciara Dove-Reid, RDN
Registered Dietitian Nutritionist

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