While dietary fat still seem to have a hard time to be acknowledged for having other effects than just pushing our bathroom scale into unintended spheres in general, in the world of scientific research it is well agreed upon that certain fatty acids just aren’t essential to our organism but even seem to improve our general health if they are consumed in particular amounts and/or in specific times during our lifespan.
Two of these fatty acids are called docosahexaeonic acid, abbreviated as the more famous term DHA, and eicosapentaenoic acid, abbreviated as EPA. Those two acids belong to both classes of long-chained poly unsaturated fatty acids and omega-3 fatty acids which are proven to reduce inflammatory processes in the human body as they are competitive inhibitors of omega-6 fatty acids. Those fatty acids appear to have negative side effects on our health situation (mainly by increasing inflammation and oxidative stress) if they are consumed in large amounts and if the ratio of intake of omega-3 FA and omega-6 FA is shifted towards the latter. Professionals recommend a ratio of 1:5 (omega-3 : omega-6) or even up to 1:2 which still is considered to be safe, however, the actual nutritional situation of the average population in first world countries shows a different picture. Our intake of omega-6 FAs exceeds our average intake of omega-3 FAs by 10 to 15 times. Although there definitely are other factors which have to be taken into account, this ratio apparently is one of the more important reasons for stroke deseases and correlated medical conditions.
Despite other omega-3 FAs DHA and EPA have shown to directly improve not only the function of the human heart and eyes, but furthermore is critical to optimal nervous and brain development as DHA is the predominant fatty acid in the cerebral cortex. Studies have shown that children who lacked of DHA in their infant state appear to have slightly reduced cognitive capacities compared to children with sufficient supply of DHA at an early age.
Yet it is easy to adjust your diet according to recommended specifications (for example by adding or focusing more on linseed and rapeseed oil), DHA and EPA in particular still are very likely marginally present in your daily diet. In fact our organism can synthesize DHA out from another omega-3 FA called alpha-Linolenic acid by itself. Given the fact that at the end of this enzymatic pathway the outcome of DHA is very low though, it’s recommended to supply the body with dietary DHA. Generally speaking adequate dietary sources for DHA and EPA are very limited to such as:
- fatty sea fishes as tuna, herring, salmon and mackerel
- chicken eggs (if the maternal chicken was fed with sufficient amount of omega-3 fatty acids)
While chicken eggs as source are negligible more or less, fatty sea fishes should be consumed every second day in order to ensure the intake of a decent amount of DHA & EPA over the longterm. On average as a normal person you should aim for 250 mg of DHA and EPA per day in order to profit from its health contribution to eyesight, brain and heart function, however, intakes up to 3000 mg per day are considered to be safe and seem to provide additional health benefits on blood pressure and fat metabolism.
Benefits of omega-3 fatty acids during pregnancy
Several studies have shown that a higher intake of DHA and EPA in particular results in longer gestation and slightly higher birth weight of the infants. The reason for that is strongly assumed to be the altered synthesis of so-called eicosanoids – bioactive compounds which are metabolites of omega-6 and omega-3 fatty acids. While omega 6 fatty acids enhance production of eicosanoids which are strongly associated with the initiation of labor and preterm labor, omega-3 fatty acids, especially EPA, enhance production of certain prostaglandines which are capable of promoting relaxation of the uterus, thus delaying labor.
Besides influencing gestation itself, both EPA and especially DHA seem to promote postnatal development of the central and peripheral nervous system of the child as well, augmenting their coordination of their eyes and hands and even their IQ in the longterm. As the most rapid development of neural and retinal development occurs in the second half of pregnancy, usually a sufficient intake of DHA is especially recommended during that time.
Evaluating the need of a EPA and DHA supplementation
Although the advantages of a sufficient intake of EPA and DHA during pregnancy are at hand, in western society we still can observe a huge lack of consumption of these fatty acids. A canadian study (Denomme et. al, 2005) showed that north american pregnant women only consum 1,5 g of omega-3 fatty acids per day of which only 117 mg of EPA and DHA contribute to their own well being and the health of their unborn child. Considering that official nutrition departments and organizations as the European Food Safety Authority recommend more than double the amount for average non-pregnant people, those numbers indeed are too low to match a pregnant women’s needs of EPA and DHA.
In addition to that we can observe an decrease in average sea food intake, especially in the USA. In a review of the 1999–2000 National Health and Nutrition Examination it was concluded that only 19% of American adults consume the recommended 2 servings of fish each week. Although this amount already should be enough to cover the needs of DHA and EPA for the average person (100 to 250 mg per day of omega-3 fatty acids, of which 50 to 100 mg is from DHA), it still is not enough for pregnant women who should aim for a dietary goal for 650 mg omega-3 fatty acids (containing 300 mg DHA) per day (Simopoulos et. al, 1999).
Basically only two options are left to reach that recommended goal: Either consuming more fish or using fish oil supplements delivering the necessary amounts of omega-3 fatty acids. However, if we consider eating three or even six times the recommended amount of sea food, aside from the taste aspect, we need to take into account the mercury pollution. To avoid unnecessary high mercury intake the quality of consumed fish needs to be respected as well as the origin of the food.
In contrast fish oil supplements represent an easy and cheap way to supply a pregnant woman’s body with omega-3 fatty acids. Fish oil supplements are commercially available from multiple companies. The amount of EPA and DHA per capsule varies, but most contain one-third to one-half of these omega-3 fatty acids (eg, in a 1000-mg capsule, 300 or 500 mg would come from EPA and DHA). Most commercially available fish oil supplements contain less than 1 to 2 ppb of mercury compared with less than 0.05 ppb in seafood, but because the amount of fish oil used (1–2 g a day) is much smaller than what is consumed when eating seafood (200 g twice a week), the risk of mercury toxicity is inconsequential.