4Nofima-Norwegian Institute of Food, Fisheries and Aquaculture Research, 1430 Ås, Norway; on. amifon@vonsark. ieskela (A. K. ); on. amifon@retyur. etneb (B. R. ); on. amifon@eybtso. irak-enot (T. -K. K. Ø. )Find articles by.
4Nofima-Norwegian Institute of Food, Fisheries and Aquaculture Research, 1430 Ås, Norway; on. amifon@vonsark. ieskela (A. K. ); on. amifon@retyur. etneb (B. R. ); on. amifon@eybtso. irak-enot (T. -K. K. Ø. )Find articles by.
4Nofima-Norwegian Institute of Food, Fisheries and Aquaculture Research, 1430 Ås, Norway; on. amifon@vonsark. ieskela (A. K. ); on. amifon@retyur. etneb (B. R. ); on. amifon@eybtso. irak-enot (T. -K. K. Ø. )Find articles by.
Feed safety is important for both the health and well-being of animals and for the safety and health of people who eat them. Wheat gluten (WG) is a good source of protein for fish food because it can be used to bind the food together, is easy for fish to digest, has a good amino acid profile, is high in energy, and, most importantly, has few anti-nutritional factors (ANFs). The main goal of this study was to find out how WG in the diet affects salmon health by looking at their growth, how well they use their food, and the transcriptomes of their liver and intestines. There were two types of diets that the fish were fed: a control diet with fishmeal (FM) as the only source of protein and diets where 15% or 20% of the FM was replaced by WG. The fish weighed an average of 223 grams at the start of the experiment, and they gained about twice as much weight during the 9 weeks. Salmon fed on 30% WG showed reduced feed intake compared to the 15% and FM fed groups. The liver was the organ that was least affected by the WG, but the amount of fat and activities of liver health markers in plasma went up. Gene expression analysis showed significant changes in both, intestine and liver of fish fed with 30% WG. Changes in the lipid metabolism, especially in the transport of lipoproteins and sterols through the intestines, were especially clear. Also, the intestinal transcriptome of fish that were fed WG showed changes in the expression of many genes that are in charge of immunity and tissue structure and integrity. These observations implied that the fish receiving WG-containing diet were undergoing nutritional stress. Overall, the study showed that a high WG level in the diet can hurt the intestinal and liver health of salmon, causing symptoms that are similar to those seen in people who are sensitive to gluten.
The world population is currently 7. 8 billion and expected to increase by 2 billion by 2050. Between 1961 and 2016, the population growth (3. 2%) outpaced the food production (1. 6%) and also exceeded the total meat production (2. 8%) [1]. However, the fish consumption is increasing constantly at an average rate of 1. 5% per year, and the UN says that one in five people depend on fish as their main source of protein. This tremendous growth depends directly on the availability of feed resources. Atlantic salmon (Salmo salar), which is a commercially important species [1], is mostly grown in Norway, with exports rising by 4% from 2019 to 2020 [2]. Fish consumption is expected to increase in the coming years to meet the demands of the growing population. People eat fish because it gives us essential amino acids, omega-3 long chain polyunsaturated fatty acids like eicosapentaenoic acid and docosahexaenoic acid, essential minerals (Ca, P, Zn, Fe, Se, I), and vitamins (A, B, D) [3]. Along with the growth of aquaculture comes the need for more feed, which means that different feed ingredients are needed. The amounts of fishmeal (FM) and fish oil (FO) that Atlantic salmon eat have gone down from 90% in 1990 to 4% in 2014. 5% in 2016 [4,5]. Because FM and FO are less available around the world, feed ingredients are switching to plant-based ones. This change was also pushed by growing market pressure to make fish farming more environmentally friendly [6]. As a result, the marine protein dependency ratio dropped from 3 to 2. 8 kg (1990) for 1 kg of salmon to 0. 7 (2013), along with a parallel decrease in the use of marine oils [4].
Novel protein sources, e. g. , from insects, are commercially available, but plant-based materials continue to be the prevalent replacement for marine ingredients. Soybean protein concentrate (SPC), wheat and wheat gluten (WG), corn, faba beans, sunflower meal, pea protein concentrate, and other vegetable proteins are used a lot [5]. The best way for Atlantic salmon to grow depends on many things, including their genes, how they are raised, what they eat, and how the food is made and processed [7]. Feed processing has a significant impact on the nutritional quality and digestible energy of the complete diet [8]. Soybean meal has been shown to make salmon get enteritis, but alcohol-extracted SPC doesn’t seem to have any effect on the fish’s growth or intestinal integrity, and it even helps them gain weight more effectively than FM [9]. However, some studies have shown that protein concentrates from soy and pea can also cause mild changes in the intestines of salmon, but WG did not have the same effects [10]. WG is a good pellet binder in extruded diets. This substance is easily absorbed by fish [11] and can be used instead of up to 35% of FM in salmon diets without having major negative effects [12]. Because of this, it is widely accepted as an ingredient in fish diets. However, higher levels can only be incorporated after adequate supplementation with limiting amino acids, especially lysine.
Adding plant-based ingredients to fish food could be dangerous because they contain chemical contaminants and antinutritional factors (ANFs) like phytoestrogens and mycotoxins that can make it harder for fish to digest, absorb, and use nutrients, which can hurt their health and growth [13]. It’s possible for unwanted substances to be present in feed at low levels and go unnoticed because of a lack of analysis, methods with low detection limits, or the lack of reference standards. However, their presence alone or together may be harmful. Dietary exposure to harmful contaminants can be detected by transcriptomic analysis showing affected pathways. WG contains comparably less ANF than protein concentrates from legumes [11]. However, major protein fractions in WG, i. e. gliadins and glutenins [14], are linked to a number of intestinal health problems and issues in people [15]. So far, sensitivity to wheat gluten has not been reported in fish.
A lot of different proteins are being looked at as possible new ingredients in fish food to replace FM. This means that the effects on fish metabolism, health, and growth must be carefully studied using methods from many different fields. The goal of this study was to find out how WG affects Atlantic salmon’s growth, metabolism, feed efficiency, and intestinal health. WG was added to the diet at two levels: 15% or 30%. It was compared to a diet that only had FM as the protein source. Blood parameters and liver fat were analysed to identify potential health effects. We used microarray analysis to look at gene expression profiles to see how the response changed in the intestine and liver, which are both metabolically important tissues.
Salmon is a popular fish that is consumed worldwide It is rich in healthy fats like omega-3s and is loaded with protein. Many health-conscious people eat salmon regularly as part of a balanced diet However, people with celiac disease or gluten sensitivity wonder if salmon is really gluten-free. After all, many sauces and marinades contain gluten, so could the salmon itself contain gluten?
In this article, we’ll take an in-depth look at salmon and gluten to help you determine if salmon is safe to eat on a gluten-free diet
What is Gluten?
Before we talk about whether salmon has gluten, let’s talk about what gluten is.
Grains like wheat, barley, and rye contain a group of proteins called gluten. The gluten proteins in these grains form a sticky network when flour from them is mixed with water. This is what makes bread and other baked goods chewy.
For most people, gluten poses no issues. However, for those with celiac disease or non-celiac gluten sensitivity, gluten triggers an immune response that damages the small intestine. Even small amounts of gluten can cause symptoms like abdominal pain, bloating, diarrhea, constipation, vomiting, fatigue, headache, and more in gluten-sensitive individuals.
The only treatment for celiac disease is strictly following a 100% gluten-free diet. This means reading labels carefully and avoiding any foods or ingredients that contain wheat, barley, rye, and their derivatives.
Is Salmon Naturally Gluten-Free?
Yes, salmon is naturally gluten-free. Salmon are fish that live in rivers and the ocean. They eat plankton, insects, and smaller fish. It does not consume grains, so salmon does not naturally contain any gluten.
All plain, fresh fish and seafood are gluten-free, including popular choices like:
- Salmon
- Tuna
- Cod
- Mahi mahi
- Snapper
- Shrimp
- Crab
- Lobster
- Scallops
- Clams
- Mussels
So if you buy a fresh salmon fillet at the fish market or catch a salmon yourself and cook it plain, you can be assured it is 100% gluten-free. There is no natural gluten present in any fish.
Can Salmon Be Contaminated With Gluten?
While salmon does not inherently contain gluten, there are some cases where it could potentially be contaminated:
1. Added Ingredients
Many packaged, processed fish products have additional ingredients added, like:
- Bread crumbs or batter (for fried fish)
- Soy sauce or teriyaki marinade
- Spices and seasonings
Always check the label of any seasoned or marinated salmon to look for gluten-containing additives like soy sauce, wheat flour, malt vinegar, barley malt, and more.
2. Cross-Contact During Processing
If salmon is processed on shared equipment or in a shared facility with gluten-containing foods like breaded fish, cross-contact can occur. Some processing plants do take steps to prevent cross-contact by thoroughly cleaning equipment between items. Check for a “gluten-free” label to confirm the salmon was processed safely.
3. At Restaurants
Dining out with celiac disease or gluten sensitivity can be challenging. Even if you order gluten-free salmon, cross-contact could occur from shared cooking surfaces, utensils, or fryer oil. Fried fish is especially high risk, since restaurants often use the same fryer for breaded and plain items.
To stay safe, check to see if the restaurant has specific gluten-free cooking protocols before ordering fish. Opt for grilled, poached, or broiled salmon instead of fried. And of course, confirm that any marinade or seasoning is gluten-free.
How to Buy Gluten-Free Salmon
Here are some tips for purchasing salmon that is guaranteed gluten-free:
-
Buy wild-caught salmon. Wild salmon like sockeye and king salmon will not have been fed any gluten-containing grains.
-
Check for a gluten-free label. Look for packaged salmon labeled “gluten-free” to ensure safety from cross-contact.
-
Shop at dedicated gluten-free brands. Companies like Trident, Lucy’s, and Tasty Catch sell gluten-free canned and pouched salmon.
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Purchase fresh salmon and add your own seasoning. Buying a raw salmon fillet and cooking it yourself lets you control ingredients.
-
Ask questions at the fish counter. Inquire about their suppliers and production methods to assess risk.
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Opt for reputable grocery chains. Stores like Whole Foods, Trader Joe’s, and Costco have strict protocols for allergen control.
Does Smoked Salmon Contain Gluten?
Smoked salmon is a popular delicacy, often eaten on bagels or crackers. But is smoked salmon gluten-free?
Most smoked salmon is naturally gluten-free, since smoking is a preservation method that involves treating raw salmon with salt and smoking it over wood chips. Some types of smoked salmon to look for:
- Nova smoked salmon
- Scottish smoked salmon
- Lox (brined rather than smoked)
However, there are two potential concerns with smoked salmon:
1. Added flavorings: Some smoked salmon contains honey, bourbon, spices, or other glutenous flavorings. Check the ingredients list to confirm the product is gluten-free.
2. Cross-contact: If processed on shared equipment with gluten-containing foods, cross-contact could occur. Look for brands that label their smoked salmon “gluten-free” for assurance.
As long as you verify there are no questionable ingredients or cross-contact issues, most smoked salmon is safe to eat on a gluten-free diet.
Common Questions About Salmon and Gluten
Here are answers to some frequently asked questions about salmon and gluten:
Is salmon safe for celiac disease? Yes, plain salmon is naturally gluten-free and safe for those with celiac disease, as long as any added ingredients are also gluten-free.
Can you eat salmon if you are gluten intolerant? Yes, salmon is safe for non-celiac gluten sensitivity. Stick to plain, unseasoned salmon or use gluten-free seasoning.
Does salmon have wheat in it? No, salmon does not naturally contain wheat or gluten. Only choose salmon with no wheat-based additives.
Can salmon be contaminated with gluten? It is possible but uncommon. Contamination risk increases if not labeled gluten-free or bought from unsafe sources.
Is wild caught salmon gluten-free? Yes, wild salmon is naturally gluten-free since it does not consume grains. Farmed salmon could potentially be given gluten-containing feed.
Is canned salmon gluten-free? Most canned salmon is gluten-free, but always verify by reading the ingredients for additives. Look for brands that state “gluten-free” for assurance.
Gluten-Free Salmon Recipes
Salmon is very versatile. It can be grilled, baked, broiled, poached, fried, and even eaten raw in sushi and poke bowls. Here are some delicious gluten-free salmon recipes to inspire your cooking:
Grilled Salmon with Lemon Butter
- Salmon fillets grilled to perfection and topped with flavorful lemon butter.
Baked Salmon Cakes
- Grab your can of salmon and whip up these crispy, gluten-free salmon cakes.
Broiled Salmon with Avocado Salsa
- Top broiled salmon with a fresh salsa of avocado, tomato, lime, and cilantro.
Poached Salmon Salad
- Salmon poached in broth served atop a salad of greens, oranges, and roasted beets.
Air Fryer Salmon
- Get crispy salmon without the oil by cooking it in an air fryer!
Lox Bagel Breakfast Sandwiches
- Recreate a classic sandwich using gluten-free bagels, cream cheese, lox, and all the fixings.
Teriyaki Salmon Stir Fry
- Salmon provides protein in this quick Asian stir fry with vegetables and gluten-free teriyaki sauce over rice.
Smoked Salmon Deviled Eggs
- Stuff your deviled eggs with creamy filling and delicious smoked salmon.
Cajun Blackened Salmon
- Give your salmon a kick of heat and flavor with Cajun seasoning and a quick pan-sear.
The Verdict on Salmon and Gluten
After reviewing the facts, the answer is clear – salmon is inherently gluten-free. While there is a small risk of contamination from manufacturing or kitchen practices, overall salmon is considered safe for gluten-free and celiac diets.
Of course, always verify packaged salmon is labeled gluten-free and limit risk by purchasing high-quality salmon from reputable sources. When dining out, check on preparation practices before ordering fish.
As long as you take precautions, you can confidently enjoy delicious gluten-free salmon baked, grilled, smoked, or in your favorite recipes. Salmon provides amazing health benefits like omega-3s, high-quality protein, B vitamins, potassium, and selenium.
Eating salmon
Materials and Methods
At the Nofima Feed Technology Center in Fyllingsdalen, Norway, fish diets were made by replacing some or all of the fish meal with WG, a plant-based protein source. The feed materials came from the businesses Norsildmel AS (FM) in Bergen, Norway, and Tereos Syral (WG) in Marckolsheim, France. The plant parts that were used were of good quality and had very small amounts of harmful chemicals like mycotoxins, often not even enough to be detected [16]. So, we thought that any changes in gene expression in different salmon tissues were not due to these contaminants but were a direct result of the WG being in the fish’s food. The manufacturing process of the experimental diets for salmon has been reported previously in detail [16]. Diet formulations and compositions are given in . Total proteins, dry matter, lipids, and energy levels in the fish diets were made so that they were pretty much the same for all diet groups. The pellet size was adjusted to the size of the on-growing salmon. All non-oil ingredients were mixed, extruded, dried, and coated with oil. Yttrium oxide was included at 0. 01% as an indigestible inert marker to quantify apparent nutrient digestibility. The diets were not balanced for amino acids and the other nutrients.
| FM (Control) | WG15 | WG30 | |
|---|---|---|---|
| Diet composition (g/100 g) | |||
| Fishmeal | 63.35 | 48.35 | 33.35 |
| Wheat | 12.0 | 12.0 | 12.0 |
| Wheat gluten * | – | 15.0 | 30.0 |
| Fish oil | 20.0 | 20.0 | 20.0 |
| Additives # | 4.65 | 4.65 | 4.65 |
| Total protein | 45.2 | 46.7 | 48.1 |
| Total lipids | 26.5 | 25.4 | 24.3 |
| Chemical content (% in diet) | |||
| Dry matter | 93.6 | 93.9 | 94.1 |
| Protein | 45.2 | 46.7 | 48.1 |
| Lipid | 26.5 | 25.4 | 24.3 |
| Ash | 13.5 | 11.0 | 8.6 |
| Energy (MJ/kg) | 21.3 | 21.2 | 21.1 |
| Yttrium | 0.007 | 0.007 | 0.007 |
3. Blood Serum Analysis
Free fatty acids (FFA), total protein (Tprot), triglycerides (TG), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were some of the serum parameters that were changed by the diets. The FFA levels were lower in both WG groups as compared to the FM-fed control group. But the WG30 group had more Tprot and ALT in their blood than both the WG15 group and the FM group. Moreover, there was a strong trend towards higher AST levels in the WG30 group.
| FM | WG15 | WG30 | p-Value | |
|---|---|---|---|---|
| FFA (mmol/L) | 0.41 ± 0.02 a | 0.29 ± 0.01 b | 0.31 ± 0.02 b | 0.01 |
| Tprot (g/L) | 42.9 ± 1.1 b | 40.7 ± 1.0 b | 50.3 ± 1.8 a | 0.02 |
| TG (mmol/L) | 3.75 ± 0.22 | 3.48 ± 0.33 | 5.15 ± 0.67 | 0.31 |
| ALT (U/L) | 36.7 ± 2.7 b | 26.1 ± 2.3 b | 81.3 ± 17.8 a | 0.04 |
| AST (U/L) | 1082 ± 143 | 763 ± 100 | 3116 ± 827 | 0.09 |