Introduction

Loss of muscle mass puts a person at greater risk of chronic disease, leading to weakness, and reduced quality of life. As we age, it is a major contributor to disease. A healthy, balanced diet that includes oily fish can help to prevent muscle loss.¹ According to the National Health Service (NHS), people should eat at least two portions of fish per week, including one portion of oily fish. Oily fish (such as sardines, trout, and salmon) contain 5-20% fat, whereas white fish (such as cod, pangasius, haddock, and tilapia) typically contain only 1-2% fat.³ Oil-rich fish contain long-chain omega-3 and omega-6 fatty acids, which can prevent heart disease and improve overall health.² In addition to these benefits, oil-rich fish, such as sardines, can be useful for supporting your muscles.

In this article, you will find out which nutrients sardines contain, how it can improve and maintain your muscle health, and how to incorporate sardines into your dietary plan.

Nutritional profile of sardines

Sardines are oil-rich fish, which means that they are a good source of essential fatty acids, which are the building blocks of lipids (fats). Whilst all dietary fat is composed of fatty acids, not all fatty acids are essential. Essential fatty acids are those that the body cannot produce, so it needs a dietary supply of them. There are three types of fatty acids: saturated, monounsaturated, and polyunsaturated fatty acids (PUFAs). Different foods contain varying ratios of these fatty acids.

Omega-3 fatty acids are essential PUFAs commonly found in marine oily fish. The two most well-known omega-3 PUFAs, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are found in sardines.^4,5

Nutrition profile of sardines (values per 100 grams):⁵

Despite their richness in healthy nutrients, sardines contain relatively few calories compared to other types of fish and seafood. Raw sardines (flesh only, 100 grams) contain 134 kcal, whilst the same amount of mackerel contains 233 kcal, and trout contains 127 kcals.⁴ 

Muscle support with sardines

Muscle anabolism

There is growing evidence that omega-3 PUFAs, especially EPA, improve protein synthesis (anabolism) and reduce protein breakdown (catabolism) in skeletal muscle. The balance between these two processes is essential for muscle growth and the maintenance of muscle mass. 

Some studies also indicate that omega-3 PUFAs may improve muscle function in combination with physical exercises, especially in older adults.Omega-3 PUFA intake may reduce the loss of muscle mass during periods of inactivity due to illness or injury. It may also enhance the body's response to protein intake, promoting muscle growth. These positive effects of omega-3 PUFAs on muscle mass and muscle function may be useful for preventing muscle wasting, such as sarcopenia.

Although many studies emphasise the benefits of omega-3 fatty acids, some animal studies also suggest that omega-3 supplementation may slow muscle recovery after a period of downtime, so human studies are needed to investigate this further.¹

Muscle metabolic flexibility and insulin resistance

Skeletal muscles can switch between using fats and glucose as a source of fuel. This ability, known as metabolic flexibility, is often reduced in people with obesity and type 2 diabetes. 

Omega-3 PUFAs can enhance the muscles’ ability to use different energy sources, although results are controversial across studies. Some studies suggest omega-3 PUFAs can promote the incorporation of fatty acids in complex lipids within the muscle, thus reducing harmful lipid accumulation that can interfere with insulin signalling.

Studies indicate that omega-3 PUFAs supplementation can increase fat oxidation and decrease glucose utilisation in healthy people, suggesting a shift towards using fat as a primary energy source during physical activities like exercise.¹

Inflammation

Besides their direct effects on metabolism, omega-3 PUFAs have significant anti-inflammatory effects, which could indirectly improve insulin sensitivity. In contrast, omega-6 PUFAs, especially arachidonic acid, tend to promote inflammation. While some inflammation is necessary for muscle adaptation, excessive or chronic inflammation can contribute to health issues like insulin resistance and obesity. This is not to say that you should avoid omega-6 PUFAs, as they are essential and play various roles in our body. What’s more important is avoiding a very high omega-3 to omega-6 ratio, typically seen in Western diets.

Omega 3-PUFAs (EPA and DHA) can change how inflammatory mediators like prostaglandins and leukotrienes are produced, mainly by replacing arachidonic acid in cell membranes and thus reducing the production of eicosanoids - substances causing inflammation. In addition, omega-3 fatty acids may affect various aspects of immune function. They can enhance the activity of white blood cells like lymphocytes and natural killer cells, which help regulate inflammation.¹

Cell membrane effects

Omega-3 PUFAs can significantly change the composition of cell membranes, even in small subcellular structures like mitochondria. By incorporating themselves into cell membranes, omega-3 PUFAs can enhance the fluidity of these membranes. This change in fluidity can potentially improve functions like the fusion of glucose transporters to the membrane, which is crucial for glucose intake into cells.

Most studies on the impact of omega-3 PUFAs on membrane composition and function have been conducted in immune cells or other cell lines, not specifically in human skeletal muscle cells. More research is needed to understand how these effects translate to skeletal muscle and whether they differ among various muscle fibre types.¹

Sardines as a part of your daily dietary plan

Sardines can allow you to maintain health and support muscles as part of a healthy, balanced diet. Sardines can be a component of salads, sandwiches, and main dishes such as pasta. It can be easily combined with vegetables, fruits, grains, and olive oil, which enhances its health benefits.⁶  Make sure that sardines have been stored and prepared appropriately. It’s not safe to eat raw sardines, so you can use heat-treated or ready-to-eat pickled and canned sardines.²

Here's a recipe for a simple salad with sardines and vegetables for 6 servings:

• Sardines - 3 cans
• Frozen peas and carrots - 1 package
• Cut green beans, drained - 1 can
• Sliced celery - 1 cup
• Chopped onion - 14 cup
• Chopped green pepper - 14 cup
• Chopped red pepper  - 1 tablespoon
• Lettuce - for serving

Drain sardines and cut into large pieces. Cook the peas and carrots according to the directions on the package. Drain and cool. Combine all ingredients except the lettuce. Cover and chill. Drain. Arrange in lettuce cups and garnish with red pepper strips. Dress with olive oil or any dressing of your choice.⁷ Any of the ingredients can be subtracted or replaced according to personal preference. Experimenting with different flavour combinations is a good way of discovering how you prefer your sardines.

Precautionary measures: what to look out for

Allergic reactions

Like each food ingredient, sardines may cause intolerance and allergic reactions in some individuals. You should take precautions, especially if you eat sardines for the first time or offer them to other people. If you have any doubts, it’s better to ask advice from a doctor or nutritional specialist. People who have an allergy to one type of fish often react to other types. Cooking fish does not reduce the likelihood of allergic reactions.²

Large portions and a monotonous diet

You should also avoid large portions and a monotonous diet based mostly on sardines. Firstly, large portions and a monotonous diet may lead to a disbalance of nutrients and increase the risk of allergic reactions and other diseases. In addition, eating only one or a few kinds of fish can decrease the population of these fish due to overfishing and damage the environment.²

Medications and supplements

If you take any medications, carefully read the instructions for their use. Some medicines are incompatible with certain food products. If you take cod liver oil supplements, remember that they contain lots of vitamin A. Excess vitamin A could be harmful, especially from a long-term perspective. Total intake of vitamin A should not exceed 1.5 mg per day from both food and supplements. Pregnant women should avoid taking supplements with vitamin A, and should be especially careful not to eat excessive oily fish.²

FAQs

Which fish is best for muscles?

Sardines are oily fish that contain long-chain omega-3 fatty acids and are rich in vitamins and minerals. Therefore, sardines can help you improve your overall health and support your muscles. Omega-3 fatty acids are essential for muscle development and health; they can improve protein synthesis and reduce protein breakdown in muscles.

Is it OK to eat sardines every day?

Due to their relatively low-calorie content, sardines are well-suited to most diets. Sardines are rich in vitamins and minerals, as well as fatty acids, so they can diversify and saturate your diet with healthy nutrients. However, you should also avoid large portions and a monotonous diet based mostly on sardines or any other kind of fish.

At what meals are sardines healthier?

Sardines can be a component of salads and main dishes. Sardines can be easily combined with vegetables, fruits, grains, and olive oil, which enhances their health benefits. Make sure that the sardines have been stored and prepared appropriately.

Summary

A diet that includes sardines can improve and support the health of your muscles due to their rich nutritional profile with polyunsaturated fatty acids, vitamins and minerals, and low-calorie content. You can easily incorporate sardines into your healthy daily dietary plan and prepare lots of meals with them. Sardines can help you stay healthy and strong.