Introduction

Joint Inflammation or arthritis is one of the common diseases in the UK. Over 10 million people in the UK develop arthritis and this happens in women more than men. This risk of arthritis is higher when getting older, the median age of a symptom normally starts at 55 years.¹

Dietary intervention is one of the choices in treating arthritis. Sardines rich in essential nutrients could be recommended as a choice for meals for people who are interested in taking care of joint health. 

Overview of joint health and joint diseases

A joint is an area where 2 or more bones connect and help in the movement and structure of the body. Joints are divided into 3 groups based on the types of tissue around joints; fibrous joints, cartilaginous joints and synovial joints.² Synovial joints are freely movable and are the main part of body function.

The synovial joint has a joint cavity and synovial fluid in order to prevent abrasion of bones. In the joint cavity, articular cartilage covers the surface between 2 bones and they are all surrounded by an articular capsule. The synovial joint or cavity is filled with synovial fluid. An example of this type is a knee.

Clinical significance of synovial joints

Arthritis or Joint inflammation is associated with synovial joint damage. Therefore, this article will mainly focus on synovial joints. Osteoarthritis (OA), the most common type of arthritis, results from the gradual destruction of the synovial joint and is followed by the articular cartilage getting thinner.

It is normally found in elderly people who have experienced joint injury before or doing some sports with high impact on the joint or overweight people. When the articular cartilage is thinner, the joint will compromise by excessive synovial fluid production. This leads to swelling and inflammation in the articular capsule bringing about pain and stiffness in the joint.²

Rheumatoid arthritis (RA) is one of joint inflammation related to defects in autoimmune disease in the long term. The immune response in the lining joint, known as the synovial membrane induces inflammatory cells to gather around these areas which leads to the destruction of cartilage and bone.³

However, some healthy people who overuse the synovial joint or excessive exercise also develop inflammation of the synovial membrane.²

Introduction to sardines as a potential source of joint support

Sardines are one type of small fish that are normally found in many countries such as India, the Philippines, Portugal and the Mediterranean. It is a small, oily fish rich in beneficial nutrients which can reduce the risk of heart disease, and improve bone function.^4-5

Sardines are rich in good lipids or omega-3, amino acids, minerals such as calcium or iron and vitamins such as vitamin D and vitamin B12.^4-5 This essential nutrition shows benefits in reducing the risk of heart disease, improving memory, brain development and bone function.^4,6

Nutritional profile of sardines

Overview of sardines' nutrient composition

Sardines contain high protein and are a source of calcium, iron, omega-3 fatty acids, and vitamin D.^4-5 Marine omega-3 provides many health benefits, anti-inflammatory effects, boosting immune response, reducing heart disease risk and improving some brain disorders.^4,6-7

Key nutrients in sardines beneficial for joint health

1. Omega-3 fatty acids

The key nutrition from sardines in joint inflammation is omega-3 consisting of eicosapentaenoic (EPA) and docosahexaenoic (DHA) fatty acids, which can prevent osteoporosis.⁴ Marine omega-3 fatty acids play an important role in the reduction of inflammation in arthritis as they decrease inflammatory mediators.⁷

2. Protein

Sardines contain various types of amino acids. L-arginine, one of the amino acids is associated with anti-inflammation in arthritis and benefit in bone loss. A study reviewed that L-arginine can prevent osteoclastogenesis induced by proinflammatory factors and decrease bone destruction.⁸

3. Minerals 

Sufficient calcium daily intake is necessary to prevent osteoporosis, and bone loss and decrease the risk of fractures.⁹ Calcium levels are associated with decreasing the risk of osteoarthritis; however, it is related to an increase in the risk of cardiovascular disease. Therefore, arthritis patients with cardiovascular disease should be careful of daily calcium levels.¹⁰

4. Vitamins (vitamin D)

Similar to calcium, vitamin D is important for increasing the quality of bones.¹¹ It controls calcium and phosphate levels in the body. Lack of vitamin D can cause bone abnormality and bone pain¹², as well as increase the risk of osteoarthritis of the knee.¹³ Therefore, vitamin D can reduce bone deformation and cartilage destruction.¹³

Mechanisms of joint support provided by sardines

Anti-inflammatory properties

Role of omega-3 fatty acids in reducing inflammation

According to Western societies, lower omega-3 intake especially EPA can increase arachidonic acid, (substrate of the inflammatory process).¹⁴ This means that fish oils rich in omega-3 (EPA, and DHA) provide an anti-inflammatory effect to treat rheumatoid arthritis, one of the most common joint inflammation.¹⁴

In vitro studies show that EPA and DHA inhibit the production of inflammatory substances.¹⁵ Moreover, studies in healthy volunteers report that the production of inflammatory mediators is reduced in the group that takes fish oil supplements.¹⁵ Furthermore, omega-3 has antioxidant effects by decreasing the production of reactive oxygen species.¹⁵

Cartilage support and repair

Influence of sardine nutrients on cartilage health

Many studies reported that DHA can protect cartilage in the animal model, reduce bone loss and promote blood vessels.¹⁶

Scientific evidence supporting sardines for joint health

Sardines are a source of necessary nutrients such as omega-3, vitamin D and calcium, providing advantages in various diseases. However, studies on sardines are rarely seen to support that eating sardines can reduce the disease because most clinical studies are conducted by using extracted nutrients.

A study recommended that daily intake of omega-3 more than 2.7 g per day for 3-4 months can decrease joint pain, morning stiffness, number of pain and use of NSAID (standard medicine used for symptomatic treatment in RA).¹⁷ Another study reported that daily taking omega-3 of >2.7 g/day for more than 3 months can reduce the use of NSAID but other clinical effects tend to improve symptoms of RA.¹⁸

Incorporating sardines into a joint supportive diet

Practical tips for including sardines in meals

Surprisingly, sardines are not only rich in essential nutrients but also provide a higher amount of nutrients, especially omega-3 and calcium when compared to other fish in the same amount. Sardines in the markets will be available in cans or raw.

They should have vegetables and some rice or noodles to make canned sardines healthier. Instead of having unhealthy snacks, you can put canned sardines on a cracker and add mustard or you can make a sardine sandwich.

Recipes and meal ideas rich in sardines and other joint-supportive ingredients

Including sardines in your recipes will boost your joint health. This article will provide some ideas for creating your healthy delicious meal plan. First, starting Monday morning with a sardine salad sandwich is an easy meal only basic ingredients plus with a squeeze of lemon.

Then, lunchtime with a bowl of Spanish rice with sardines in tomato sauce. Finally, dinner with Mediterranean sardine pasta with lemon, capers and chilli flakes.¹⁹ Not only these recommended meals but also you can add sardines to your daily meals in any type of cuisine.²⁰

Considerations and precautions

Allergies and sensitivities

Fish allergy is frequently found in children, and sardines are reported as the most prevalent fish species.²¹ The frequently reported allergic reactions are skin rash, stomach pain or difficulty breathing.²¹

Mercury and heavy metal concerns

Fish can contain high levels of toxicity, particularly, mercury and heavy metal. Mercury in high doses can destroy the nervous system in adults, seriously affect development in young children and increase the risk of cardiovascular diseases.⁵ Various studies have shown that the level of mercury found in sardines is low and does not affect consumers' health.⁵

High blood pressure

As tinned sardines have high amounts of sodium^22-23, patients who have high blood pressure should limit sodium intake because it absorbs water back and increases blood volume resulting in high blood pressure. Therefore, you should consider sodium levels from other sources and adjust them to suit the recommended daily intake.

Gout attacks

Sardines contain high purine levels which can break down into uric acid resulting in pain.^24-25 Patients with gout should find another way to receive this benefit by taking fish oil supplements.

Kidney stones

The same reason as gout attacks, containing high purine can cause kidney stones.^24,26 Moreover, high in sodium also leads to promoting calcium in urine, one of the risk factors.

Summary

Sardines are a source of beneficial nutrients for joint health, including essential fatty acids, proteins, vitamins and minerals. They are also inexpensive with high omega-3 content and easy to include in your daily meals. Many studies show that sardines, as a source of omega-3, calcium, and vitamin D, can help improve symptoms of joint inflammation.

Nevertheless, it should be noted that there are still not enough clinical studies to support the benefits of having canned or fresh sardines in improving joint inflammation. Therefore, consumers should have sardines in appropriate amounts and consider individual underlying diseases.