We’re told to avoid too much tuna when we’re pregnant due to high mercury levels. But can babies eat tuna?
If you’re ok eating fish, it’s not a question of never eating tuna, but how much is ok to consume each week.
Benefits of eating tuna fish
Tuna is a high protein food, with around 24g of protein per 100g. Protein is important for sustaining our energy levels and forming the building blocks of growth, which is very important for small children.
Are there omega 3 fats in tinned tuna?
Whilst a fresh tuna steak has some omega 3 fats, most tinned tuna has had the fat removed, and will not help you increase your omega 3 intake.
To get the most omega 3 fats out of your tuna, choose tuna in water rather rather than oil.
This is because when you drain the oil out of the can some of the omega 3 fats that get absorbed with the oil will also be drained away.
Do we need to worry about mercury?
We know we need to limit consumption of larger fish when we’re trying for a baby or pregnant due to mercury toxicity. This is because mercury can damage neurological development, so it might affect a growing baby.
Heavy metals are difficult to detox from the human body, and it’s not easy to detect an imbalance. The symptoms might be confused with other conditions.
Some possible signs of mercury poisoning include slurred speech, delayed development, nerve or joint pain, headaches, hair loss, or fatigue.
How do fish pick up mercury?
Mercury gets into the air and water from pollution such as fossil fuel burning, waste pollution into the seas and it also naturally occurs in the environment.
Fish absorb the mercury through their life, so the longer living, bigger fish tend to absorb more.
It’s thought the half life of mercury (the amount of time it takes to get rid of it from the body) is two years.
How much tuna can I safely eat?
The NHS recommend no more than 4 cans of tuna a week or no more than 2 tuna steaks a week for women who are trying for a baby or pregnant.
There isn’t any further breakdown as part of the UK guidelines, but there is more data available in the US.
In America the FDA recommends the tolerable weekly intake is 0.1 mcg of mercury per kg of body weight per day.
This means if you’re 60 kg then you can tolerate 6 mcg (micrograms) of methylmercury per day, or 42 mcg a week. Some good estimates here on body weight and tolerance limits.
For comparison:
Swordfish
- has 1 mcg of mercury per gram of fish
- So 100g of swordfish gives you 100 mcg mercury.
- This means that if you’re 60kg you would reach the tolerable limit with only 6g of sword fish
- If you’re 60kg you would reach your weekly tolerable limit with 42g of sword fish
Albacore Tuna
There is more mercury in albacore than light chunk tuna.
- Albacore has 0.36 mcg of mercury per gram of fish.
- So 100g of albacore tuna gives you 36 mcg mercury.
- If you’re 60kg you would reach the daily tolerable limit with 16g of albacore tuna.
- You would reach your weekly tolerable limit of mercury exposure with 116g of albacore.
Skipjack / Light Tuna
- Light Tuna has 0.13 mcg of mercury per gram of fish.
- So 100g of skipjack tuna gives you 13 mcg mercury.
- If you’re 60kg you would reach the daily tolerable limit with 50g of skipjack / light tuna.
- If you’re 60kg you would reach the weekly tolerable limit with 350g of skipjack / light tuna (or around 2-3 cans).
Remember these guidelines haven’t been taken up in the UK, the NHS advice is still no more than 4 cans.
How much tuna can my baby safely eat?
So how does this translate to babies?
The BDA – Association of UK Dieticians – recommend we all eat two portions of fish a week, one should be oily. They recommend following fish portion sizes for children
18 months to three years | ¼ – ¾ small fillet or 1-3 tablespoons |
four to six years | ½ – 1 small fillet or 2 – 4 tablespoons |
Let’s look at the light canned tuna most commonly eaten:
- Light Tuna has 0.13 mcg of mercury per gram of fish.
- So 100g of skipjack tuna gives you 13 mcg mercury.
- If your baby is 8kg they would reach the daily tolerable limit with 6.5g of skipjack / light tuna.
- If your baby is 8kg they would reach the weekly tolerable limit with 45g of skipjack / light tuna.
With most nutrition guidelines for children I suggest looking at the weekly limits rather than daily guidelines.
Does mercury in tuna affect older children?
If your child is 16kg they would reach the weekly tolerable limit with 90g of skipjack / light tuna.
So you can see there is a difference in resulting mercury in tuna levels depending on how much you eat as a portion, the type of tuna you choose, and how often you eat it.
I’ve detailed above how much mercury is in tuna, but does that mean it all stays in our body?
There is conflicting evidence about how much mercury we eat actually gets absorbed into our cells, and estimates range from 12% to 79%.
As ever with nutrition research it can be confusing, and we also need to remember each person will have an individual response to certain foods and nutrients. If you’re worried about anything to do with your child’s diet contact us for a quick call to see if a nutrition consultation can help.
If you have any nutrition topics you’d like to know more about please get in touch via our contact form and ask.

Anna Mapson supports busy parents to get family nutrition right, taking away the stress if feeding your family. In Bristol or online via video call
- Weaning Consultations & Group Classes
- Children’s Nutrition Consultations (e.g. fussy eating, constipation, eczema, healthy growth, behaviour)


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