As with any change in diet we should first weigh the risks against the benefits. I've decided to supplement my diet with fish oil but I implore you to learn as much as possible and come to your own conclusion.
These are all the risks I've found on the net:
Warning: Fish oil shouldn't be taken with blood thinning medication - warfarin or aspirin for example. It shouldn't be taken by anyone with bleeding disorders or uncontrolled hypertension. If you are taking any medication please check with your doctor before starting the Zone and before supplementing your diet with fish oil.
Information on the levels of contaminants in various fish oils is on the different types of fish oil page.
In The Omega Zone Dr Sears lists and addresses seven "potential side effects of high dose fish oil." He claims he hasn't seen any of these effects in patients on high doses in his own trials over three years.
His list is essentially the first five points above, as well as:
He does also refer to the gastrointestinal problems and the risks from contaminants but believes that the purest oil doesn't cause them.
I'll briefly summarise Dr Sears' comments on his seven points but please read The Omega Zone if you'd like more details.
1. Excessive bleeding - He hasn't found any evidence suggesting anything more than very slight increases in bleeding time from cuts and injuries. He likens the effect to that of taking one aspirin per day.
2. Increased LDL cholesterol levels - Fish oil consumption does cause LDL [Low Density Lipoprotein] cholesterol levels to increase by an average of 5 to 10 percent (in people not in the Zone), but this is offset by a large drop in triglycerides, which lowers the TG/HDL ratio, which in turn results in more LDL being converted to a less harmful form. He adds that controlling insulin at the same time as fish oil supplementation will lower LDL cholesterol levels anyway.
3. Depression of the immune system - He doesn't believe it could be depressed enough to give rise to cancer or dangerous infections. One reason for a depression could be a decreased production of GLA [Gamma Linolenic Acid], but that could be remedied by eating two bowls of slow cooked oatmeal per week, or taking one capsule of evening primrose or borage oil per week.
4. Excess production of "good" eicosanoids - Possibly, but if signs show is easily remedied by reducing the amount of fish oil taken.
5. Increased blood sugar levels in type 2 diabetics - Early studies showed adverse effects at high doses, later studies show no effects at normal doses. His own studies indicate those following the Zone nutrition program significantly decrease their blood sugar levels.
6. Increased incidence of stroke - This possibility was raised because Eskimos in Greenland seemed to have higher stroke rates than Danes. A recent study on the Eskimos found the stroke victims had AA/EPA [Arachidonic Acid] [Eicosapentaenoic Acid] ratios three times lower than Dr Sears recommends, while this ratio in his patients taking very high doses of fish oil rarely dropped below his acceptable level.
7. Reduction of antioxidant levels - Because fish oil is prone to oxidation it can use up our antioxidants, but this can be counteracted by eating lots of vegetables and fruits, always using extra-virgin olive oil, and perhaps taking supplemental vitamin E.
The long chained fatty acids in fish oil are exactly the same as those in the fish we're encouraged to eat more of - one 210g can of salmon is comparable to 7 health grade capsules - so as you'd expect the risks from normal amounts of these fatty acids themselves are quite rare and or minor.
Having said that, the first point above should definitely be heeded, please check with your doctor if you take any medications.
The contaminants are more concerning. Gastric problems such as gas, abdominal pain, and diarrhoea are more common. The accumulation of toxic impurities is also a possibility. But as contaminant levels vary in different grades of fish oil we can minimise our risk by choosing the cleaner varieties.
And please remember that such contaminants are not limited to fish oil supplements. They're also found in whole fish, meat, eggs, and milk among others.
Personally I feel the benefits of supplementation far outweigh the risks. But, although we think it is an important part of the Zone, taking fish oil is certainly not a requirement of reaching the Zone and staying well - eating favourable foods will always be the best route to good health. So if you're at all worried about it, even if the oil never harms the worry probably will, just concentrate on healthy food choices and you'll be fine.
next > The different types