Snake oil has a bad reputation.
Originally an integral part of Oriental medicine, the product was derived from the Chinese water snake. But it's perhaps best known because it was used so heavily by Chinese immigrants who moved to the Western United States—where there are no Chinese water snakes. Still, word spread about this secret healing elixir and knockoffs quickly appeared. Sold in a carnival-like atmosphere, with over-the-top production and boisterous claims, these potions were made from other snakes—including rattlesnakes—beef fat, red pepper oil, camphor, turpentine and a host of other non-therapeutic liquids.
The original substance contained roughly 20 percent eicosapentaenoic acid (EPA), a type of omega-3 polyunsaturated fatty acid (omega-3 PUFA), but the amount found in the knockoffs fluctuated wildly. This is the same type of omega-3 found in fish like salmon, which contain a maximum of around 18 percent EPA, less than real Chinese snake oil.
Today, the claims of fish oil and other sources of omega-3 PUFAs. like krill. are hawked with no less vigor than the snake oils of old. But are they any more useful?
In terms of cardiovascular benefit, fish oil has been examined in two different contexts within two different settings. Fish oil has been studied in populations that consume lots of fish. These groups were checked for cardiovascular (CV) endpoints and the fish oil was determined by extrapolation to be the causative factor, much like antioxidants are presumed to be responsible for the beneficial CV effects seen with moderate wine consumption.
And fish oil has been studied in settings where pills and formulations are currently being sold and taken. These CV endpoints have been examined in two particular contexts: primary and secondary prevention. Primary prevention refers to preventing the occurrence of a pathological CV condition in a person or population where it does not currently exist. It prevents or reduces the incidence of CV disease in those who take it. Secondary prevention refers to preventing a recurrence of CV disease events in those who already have the disease. A great example is aspirin. For those who already have cardiovascular disease, aspirin is of benefit and a recommended therapy for secondary prevention. It prevents about 40 events per 1,000 people with cardiovascular disease who take the therapy.
In looking at primary prevention studies, most that examine fish consumption show a decrease in all cause mortality and a reduction in CV events. Translation: Eating a diet rich in fish is good for you. It reduces your risk of death and events related to cardiovascular disease, like a heart attack. When these studies were examined to tease out if using fish oil supplementation was as efficacious (or better) than eating fish, it was found that the "available studies were too heterogeneous in terms of study design, duration, background diet, methods of assessment, and outcomes to allow even indirect comparison to be meaningful."
A few large studies (examining over 14,000 people), including the JELIS (Japan Eicosapentaenoic acid (EPA) Lipid Intervention Study), looking at the addition of high-dose fish oil (1800mg EPA/day) to those taking a low-dose statin medication for primary prevention found no benefit. Translation: We have no idea if taking fish oil or other omega-3 PUFAs supplementally, in pill or any other form, prevents CV events.