Investigators looked at the ability of several nutrients to affect cell death, known as apoptosis, induces by exposure to something known as tumor necrosis factor (TNF). They found:
DHA was found to greatly reduce (40-70%) the rate of cell death
Vitamin E was found to partially inhibit the rate of cell death
EPA slightly increased the rate of cell death
Additionally, it was demonstarted that DHA became incorporated into the cell membranes, which researchers speculate is the reason for the large protective effect.
The treatment of cells with both DHA and vitamin E simultaneously was shown to produce the greatest effect of all.
The researchers suggest that ingestion of nutrients such as DHA and vitamin E might exert beneficial effects on organ dysfunction associated with various diseases related to production of TNF, such as rheumatoid arthritis and multiple sclerosis.
TNF is a peptide produced by the body that serves many useful functions when present in appropriate amounts such as contributing to the body's defense mechanisms, killing virus infected cells, killing parasites, can enhance wound healing by accelerating blood coagulation.
However, when present in too great a quantity, TNF can have adverse effects such as killing normal or healthy cells, elevating triglyceride and VLDL cholesterol levels, causing low blood pressure, and elevating metabolic rate.
Journal of Nutrition 2000;130:1095-1101
Even though EPA was found to slightly increase the rate of cell death, it was more than made up for by the tremendous positive effect of DHA. Since EPA and DHA exist naturally together in foods such as fish, there is nothing to worry about and it is most likely better to have a balance between the two, rather than to just take DHA supplements, which have become popular recently.