It is estimated that one in four Australians currently take fish oil supplements daily due to its perceived benefits.
There are suggestions that fish oil is good for a range of health conditions, including arthritis, Alzheimer’s disease, diabetes, mental health and heart disease. It’s even been suggested that fish oil could make people smarter, so should we all be taking supplements?
Good for everyone?
Fish oil usually contains DHA (docosahexaenoic acid) and EPA (eicosapentaenoic acid). In Western countries, the low dietary intake of DHA and EPA is of concern as they are not widely available in contemporary foods.
DHA and EPA are derived from “essential” fatty acids in the diet (so named because humans and other mammals cannot make these substances themselves). They are found almost exclusively in fatty cold water fish, fish oil supplements, breast milk and fortified infant formula.
The majority of research on these fatty acids has focused on DHA. And here’s what we know.
There is no doubt that the DHA present in fish oil is involved in several essential brain functions. Both laboratory research and human epidemiological studies demonstrated that a DHA deficiency can impair cognition and consumption of oily fish during pregnancy may benefit children’s cognitive functioning.
Especially for children?
DHA is known to play a critical role in human brain development and there is evidence of his importance for brain development in early childhood. In addition, several studies have positive associations demonstrated between infant blood DHA concentrations and cognition.
Indeed, long chain polyunsaturated fatty acids including DHA have been suggested as being among the main factors that can increase the intelligence of breastfed people.
But what about DHA supplementation in babies and children delivered via fish oil?
The idea that dietary DHA supplementation improves cognition in young children remains controversial. Some have even suggested that it is the our generation snake oil.
Randomized controlled trials remain the gold standard in this area of research. And the tests undertaken in this field have DHA usually administered via infant formula rather than via fish oil capsules.
What the science says
The results provide conflicting evidence.
A major review of the literature failed to identify a significant effect of DHA supplementation on cognitive development in term infants. But another suggested supplementation with a level of DHA similar to that of breast milk results in better cognitive performance in young full-term infants.
Yet the majority of trials in healthy term infants showed little Where no consistent beneficial effects on neurocognitive outcomes following dietary DHA supplementation. Importantly, supplementing infants with DHA had no negative effects on growth, development, or health.
Thus, there appears to be no compelling case for or against DHA supplementation in full-term infants for the purpose of cognitive enhancement.
Inconsistent results in this literature may be due to inadequate sample sizes, variations in the doses of DHA used, the source of DHA administered (e.g. algae or fish sources), the the age at which supplementation was initiated, the duration of supplementation, the type of cognitive or developmental assessments undertaken, the variability in participant compliance across studies, or a combination of these factors.
Genetic profile could also represent a potentially relevant factor affecting the results of the study. And sex-based differences in how long-chain polyunsaturated fatty acids are metabolized were cited as potentially relevant.
Another consideration concerns potential ceiling effects: if someone is already functioning at or near peak efficiency, supplementing the diet with DHA is unlikely to provide significant benefits.
But in premature infants – in whom there is a possible deficit in DHA status – the effects of DHA supplementation may be more positive.
Despite the lack of scientific consensus As for benefits in term infants, many infant formula manufacturers include DHA in certain products and market them as superior products with distinct cognitive benefits. This is controversial, given the lack of concrete scientific evidence to back up their claims.