Official NHS advice on fish consumption
For a balanced and healthy diet, the NHS advises that adults in the UK should aim to eat at least two portions of fish per week. A standard portion is defined as around 140g when cooked. Crucially, one of these portions should be oily fish, with the second portion being either white fish, shellfish, or another portion of oily fish.
Oily fish is particularly recommended for its high content of long-chain omega-3 fatty acids, which are vital for heart and brain health. Our bodies cannot produce these essential fats, so we must obtain them through our diet. Despite this, consumption surveys show that most Britons fall short, eating only around one portion per week on average.
Oily fish vs. White fish
Fish is broadly categorised into oily and white fish, each offering different nutritional profiles. A diverse intake is recommended to ensure a broad spectrum of vitamins and minerals.
- Oily Fish: Rich in omega-3 fatty acids, vitamin D, and vitamin A. Examples include salmon, mackerel, herring, trout, sardines, and pilchards. The NHS advises a limit on oily fish consumption for some groups due to potential pollutant accumulation.
- White Fish: Low in fat but still a good source of protein, vitamins, and minerals. Examples include cod, haddock, plaice, pollock, and hake. White fish can be consumed more frequently than oily fish for most adults, as they contain fewer pollutants.
- Shellfish: Also low in fat and a source of minerals like selenium, zinc, and iodine. Examples include prawns, mussels, and scallops.
Comparing Oily Fish and White Fish
| Feature | Oily Fish (e.g., Salmon, Mackerel) | White Fish (e.g., Cod, Haddock) |
|---|---|---|
| Fat Content | High; rich in omega-3 fatty acids | Low; lean source of protein |
| Key Nutrients | Omega-3s, Vitamin D, Vitamin A | Protein, B vitamins, some minerals |
| Pollutant Risk | Higher levels of certain pollutants (e.g., PCBs), requires consumption limits | Generally lower levels, fewer consumption limits |
| Mercury Content | Varies; generally lower in smaller oily fish (sardines), higher in large predatory fish | Varies; lower in common varieties like cod |
| Example Guideline | Max 2 portions/week for vulnerable groups | Unlimited for most adults (except certain species) |
Specific advice for vulnerable groups
Dietary recommendations differ for specific groups to minimise health risks associated with potential contaminants like mercury.
- Pregnant and breastfeeding women: Should eat no more than two portions of oily fish per week. They should completely avoid shark, swordfish, and marlin, and limit fresh tuna to two steaks or four medium cans weekly, due to higher mercury levels.
- Children and infants: Small children should be given a varied diet of fish, with a maximum of two portions of oily fish per week. Avoid giving them large predatory fish like shark, swordfish, and marlin.
Choosing sustainable and safe fish
Concern over sustainability and contaminants like mercury is valid, but can be managed with informed choices.
Tips for choosing sustainable and safe fish:
- Look for certification labels: The Marine Stewardship Council (MSC) 'blue tick' logo for wild-caught fish and the Aquaculture Stewardship Council (ASC) or Soil Association logos for farmed fish are reliable indicators of sustainable sourcing.
- Eat a variety of fish: Spreading your consumption across different species, rather than sticking to the same few, reduces pressure on specific stocks and lowers your exposure to any single type of pollutant.
- Diversify your choices: While cod, salmon, and haddock are popular, consider other sustainable and nutritious options like herring, sardines, or mackerel to broaden your intake of vitamins and minerals.
- Be aware of larger predatory fish: Larger, longer-living fish at the top of the food chain, such as shark and marlin, accumulate higher levels of mercury and should be avoided entirely by children and pregnant women.
The crucial role of omega-3s
The primary driver behind the NHS recommendation for oily fish is its omega-3 content. Omega-3s, particularly EPA and DHA, are well-documented to support heart health by lowering blood pressure and reducing triglyceride levels. They also play a significant role in brain function and development, especially during pregnancy. For those who do not eat fish, plant-based sources like flaxseed, chia seeds, and walnuts contain alpha-linolenic acid (ALA), which the body can convert into EPA and DHA, although less efficiently. High-quality supplements derived from micro-algae are another option for vegans.
Healthy cooking methods
The way fish is prepared can significantly impact its nutritional value. Opting for healthier cooking methods can help you get the most from your fish portions while avoiding unnecessary fat and salt.
A list of healthy cooking methods:
- Grilling: A fast, low-fat method that preserves the fish's natural flavour. It's an excellent way to cook fillets and steaks.
- Baking: Wrapping fish in foil or parchment with herbs and vegetables can create a flavourful and healthy meal with minimal added fat.
- Steaming: This method requires no added fat and keeps the fish moist and tender, preserving its nutrients.
- Poaching: Gently cooking fish in a flavourful liquid, such as water, milk, or stock, keeps it moist and tender without excess oil.
- Pan-frying: While not as low-fat as grilling, using a minimal amount of healthy oil (like rapeseed oil) can produce a crisp texture without excess calories.
It is wise to limit consumption of heavily fried or battered fish, which significantly increases fat content. Choosing a variety of cooking methods helps keep meals interesting and healthy.
Conclusion
To summarise, the NHS recommends eating two portions of fish per week in the UK, with one being an oily fish. This practice provides essential omega-3 fatty acids for heart and brain health. While most adults can benefit from this intake, vulnerable groups such as pregnant women, breastfeeding women, and children should adhere to specific, lower consumption limits for oily fish and be cautious of tuna and large predatory fish to minimise mercury exposure. By choosing a variety of fish, looking for certified sustainable products, and using healthy cooking methods, you can confidently integrate this nutritious food into your diet for long-term health and wellbeing.
For more detailed information on healthy cooking, consult the British Heart Foundation on omega-3 and heart health.
