Overview

Mackerel is a fish, also known as an “oily fish” due to its high content of fat, specifically omega-3 fatty acids. This type of fat is healthy as it can contribute to being part of a healthy diet for heart health. Other oily fish are the following: salmon, sardines, anchovies, herring, trout, pilchards, kippers, and swordfish, among others. Canned or fresh tuna is not considered oily fish.¹

Omega-3 fatty acid is an essential fatty acid, meaning the human body cannot synthesise it or produce it by itself and it needs to be obtained from food sources. This type of fat is also considered a “good” or “healthy” type of fat as it has multiple roles in the human organism, including cardiovascular health benefits. 

Mackerel

Nutritional profile of mackerel

Mackerel has an interesting nutritional profile. As aforementioned, mackerel is an oily fish (or “fatty fish”) as it contains a high amount of omega-3 fatty acids. This type of fatty acid is also known as “polyunsaturated fats”. Omega-3 fatty acids found in mackerel are specifically EPA and DHA (expand the abbreviations). This article will refer to EPA and DHA in mackerel as just omega-3 fatty acids. Omega-3 fatty acids are found in other food sources, but mackerel is considered a good source of this fat.

A small portion of 114 grams of cooked mackerel contains more than 1000mg of omega-3.² Mackerel contains other nutrients such as protein, vitamins (vitamins A and D), and minerals (calcium, iron, magnesium, phosphorus, potassium, sodium, zinc).³

Contaminants in mackerel

It is important to keep in mind that mackerel can contain high levels of mercury or other contaminants depending on its source. In the UK, it has been found that mackerel contains cadmium, a type of heavy metal that can be detrimental to health.⁴ Therefore, eating mackerel in moderation is important in order to obtain nutritional benefits without having excessive amounts of mercury or other pollutants like heavy metals that could affect the human body.

Sustainable sources

Nowadays, it is important to be conscious of sustainable food systems since how we consume and eat impacts the environment and climate. There are different types of mackerel in the UK; some are more sustainable than others. Further information about sustainable mackerel (and other fish species) can be found in the Marine Conservation Society.

Heart health

Cardiovascular disease

Cardiovascular disease (“CVD” or heart disease) is a non-communicable disease (not caused by an acute infection) that causes are more related to lifestyle habits, amongst other factors. CVD is the term used for different heart and blood vessel conditions, including:

• Coronary heart disease (angina, heart attack, heart failure)
• Strokes and mini-strokes (or TIAs)
• Peripheral arterial disease
• Aortic disease

CVD is the first cause of death in the UK ⁵ and worldwide.⁶ Hence, cardiovascular health is very important to look after as all population is at risk.

Risk factors

CVD has multiple risk factors, meaning that there are different factors that increase the risk of having this disease. Risk factors for CVD include modifiable (what we can change or do something about it) and non-modifiable (what we cannot change).

Modifiable risk factors

1. Unhealthy or Poor Diet
2. High Intake of Alcohol
3. Low Levels of Physical Activity
4. High-Stress Levels
5. Smoking
6. High Blood Pressure (Hypertension)
7. High Blood Cholesterol Levels
   • While sometimes genetic, it can be influenced by diet and lifestyle
8. Type 2 Diabetes  (Non-insulin dependent diabetes)
9. Obesity
   • Defined as an unhealthy high weight or Body Mass Index (BMI) above 25
10. Psychological Stress

Non-modifiable risk factors

1. Genetics
   • Family history of cardiovascular disease
2. Ethnicity
   • Higher risk in Asian, Black African, and African Caribbean populations
3. Age
   • Risk increases as we age
4. Biological Sex Assigned at Birth (AMAB vs. AFAB)
   • People assigned male at birth (AMAB) have a higher risk compared to those assigned female at birth (AFAB)

The link between mackerel and heart health benefits

Mackerel and heart health

Mackerel has been suggested to help in heart health by lowering levels of triglycerides (a type of fat in human blood) potentially with its omega-3 fatty acids content, lowering blood pressure, anti-inflammatory effects, improving circulation, and preventing blood clots. Moreover, mackerel could also help maintain a healthy normal heart rhythm with its mineral content.⁷

Current evidence to support mackerel and heart health

Some recent systematic reviews (gold standard or strongest evidence in healthcare research) have looked at the relationship between fish intake, particularly oily fish and its role in the prevention of CVD.

In the latest National Institute for Health and Care Excellence (NICE) guidelines the advice has changed for people who have had a previous heart attack and do not advise consuming oily fish to prevent another heart attack.⁸ This advice is consistent with a recent systematic review and meta-analysis. Popoff et al. (2019) found that omega-3 fatty acids probably do not provide benefits in preventing a new heart attack from happening.⁹

Systematic review and meta-analysis have found that a portion of 150g of fish a week, particularly fatty fish, reduces the risk of CVD by 10%. This should be taken within the context of a Mediterranean diet, which is rich in fruits, vegetables, grains, and fiber-rich foods.¹⁰

In another important systematic review, it was found that the intake of 1 to 2 portions of fatty fish per week is associated with a 9% reduced risk of CVD, which would represent significant prevention of coronary heart disease at a global level.¹¹

Incorporating mackerel into a healthy diet

What is a healthy diet?

An overall healthy diet should include the following:

• Mostly fruits and vegetables (5 or more servings per day)
• Starchy carbohydrates such as pasta, potatoes, bread, and rice
• Whole grains
• Protein from animal or plant sources, including beans, pulses, meat, eggs, and fish
• Dairy products like milk, yoghurt, and cheese, or suitable dairy alternatives
• Small amounts of oils and spreads
• Limited foods that are high in sugar, fat, and salt

Water is also an essential part of a healthy diet. Aim for 6-8 glasses a day.

It is recommended to consume at least two portions of fish per week, including oily fish, once a week. One portion is about 140 grams of cooked fish.¹²

Cooking and preparation method considerations

The way food is prepared and cooked can also change its characteristics and nutritional profile. Frying food adds different types of fat and overall calories. To preserve the nutritional properties of mackerel, grilling, baking, poaching, or steaming are the best cooking methods. Spices and herbs can also be added for additional flavour without altering their main nutrients.

Summary

Mackerel is a rich source of omega-3 fatty acids, which play important roles in the human body, including the reduction of cholesterol/triglycerides and therefore contributing to heart health. However, moderation is key in order to have a recommended amount of omega-3 fatty acids intake and limit the intake of possible contaminants present in mackerel.

It is important to remember that heart health has multiple factors that can contribute to it, therefore, including mackerel as part of a healthy diet and considering other lifestyle factors are important to try and prevent CVD from happening.

Frequently asked questions

Who should not eat mackerel?

Individuals who are allergic to fish should not consume mackerel as this poses a risk to their health. Other individuals that should limit consumption of oily fish (including mackerel) to two portions a week are AFABs who can get pregnant, are pregnant or breastfeeding.¹²

Should I take omega-3 supplements?

Omega-3 capsules or supplemented foods are not advised for the sole objective of preventing another heart attack. However, there appears to be no evidence of harm in consuming these.⁸

If choosing to use omega-3 supplements, try to avoid fish liver oil supplements and look at the label of the supplements, making sure that they contain about the same amount of omega-3 that would be in one to two portions of fish per week (about 450mg of EPA and DHA per day for an adult dose). Also, look at vitamin A content (should not be more than 1.5mg vitamin A) and avoid it if pregnant or planning to be pregnant.¹³