As with everything in nutritional science there isn’t a straightforward answer!
The omega 3 fatty acid, DHA is vital for foetal & early infant neuron growth & brain development. Demand increases through pregnancy & maternal stores are vital through breastfeeding. Nutrients go preferentially to the foetus, any shortcoming is to the mother’s detriment! Multiple pregnancies, particularly those close together could have a detrimental effect on the mothers health.
DHA is found in oily fish. But studies show fish consumption increases exposure to mercury & can outweigh the beneficial effect of DHA. Fish is contaminated with fat soluble pollutants such as dioxins, PCB’s and DDT. NHS guidelines; limit oily fish and tuna in pregnancy to a maximum of 2 portions a week. However 1 study showed increased levels of mercury in women that were fed 2 portions of tuna for 14 weeks. Levels slowly decrease after tuna intake was stopped.
What then is the answer? Can mothers maintain adequate DHA levels if fish is toxic? Well….
- To convert plant based omega 3 , ALA (flaxseed is the richest source) to DHA it has to undergo enzymatic conversions. Humans are poor at this conversion hence why eating oily fish rich in DHA is generally preferable. BUT the conversion rate in women of reproductive age is higher due to the regulatory effect of oestrogen so consuming flaxseed may be beneficial for pregnant women.
- Omega 6 interferes with the conversion of ALA to DHA so keep omega 6 intake low by avoiding processed foods and vegetable.
- Eat smaller oily fish such as sardines or anchovies that are rich in DHA but have a lower mercury and toxin content due to their shorter lifespan and the fact they feed on plankton. Larger fish feed on the smaller fish and live longer so have a higher accumulation of toxins. Wild Alaskan Salmon also has a short lifespan and relatively low levels of toxicity.
- Take an algae supplement rich in DHA
Above all enjoy your food and enjoy your babies!