Can oil supplements go bad? Yes, they can, and in doing so they can become worse than useless, even toxic. Here are some reasons why, and some suggestions on how to detect and avoid spoiled oil supplements.
3s and 6s
Most oils we consume, in food or otherwise, are called omega-3 and omega-6 oils, named for their chemical structure (olive oil is one of the few exceptions and is neither). Both are necessary in the diet, and in fact necessary for life. Oils are used to make hormones, for nervous system health, and to build strong cell walls to keep the good stuff in and the bad stuff out. But not all oils are the same.
Some people think that omega-3 oils are better than omega-6 oils. This is not the case; a good balance of both is needed. A frequently cited optimal ratio is 6:1 omega-6 oils to omega-3. However, American diets contain 10-30 times as much omega-6 oils as omega-3, with the higher number reflecting the diets of those who eat a lot of fried foods.
It follows, then, that most people should take more omega-3 oils to balance out the high percentage of omega-6 oils in all but the most careful diets.
The problem with omega-3 oils
Most oil-containing foods contain more omega-6s for a reason: they’re much more stable on the shelf. Omega-3 oils go rancid much more easily than omega-6s. Food growers and producers, not wanting to lose much of their saleable food supply, use omega-6 oils and grow high omega-6 produce whenever possible. Healthy oils and oil supplements, being mostly or wholly omega-3s, thus have a built-in problem of rancidity.
What is rancidity, and what’s wrong with it?
Rancidity is a chemical change to the oil that changes the oil from something the body needs to something that can be highly toxic. This chemical change also changes the taste to something bitter and nasty-tasting. However, oils that are slightly rancid might not taste all that bad, so care must be taken to avoid such spoiled oils.
An example is flaxseed oil, also known as linseed oil. Flaxseed oil as a supplement is of great nutritional benefit. But linseed oil, used in oil painting, is simply flaxseed oil that has been boiled until it develops properties that make it useful in oil painting. Boiled linseed oil is highly poisonous. So this chemical change, taken to the extreme, can turn an essential nutritional oil into something deadly.
So how can you avoid rancid oils?
The enemies of oil, which can cause a process called oxidation, are air, heat, light, and age. It is important to protect omega-3 oils from all four of these.
An example of the difference between omega-6 and omega-3 oils lies in their packaging and usage instructions. Most vegetable oils are omega-6s. Since they are stable, they can be stored in the pantry in a large clear plastic bottle for years and used for cooking. An omega-3 oil such as flaxseed oil, on the other hand, is sold in a small opaque black plastic bottle in the refrigerated section of the store, with an expiration date of about six months from purchase date and instructions to keep it refrigerated. Such oils should never be used for cooking or even heated.
So the bottom line with omega-3 nutritional oils is to:
- Buy them from a refrigerated case.
- Keep them refrigerated at home.
- Get only oils in dark, opaque bottles.
- Keep the bottle tightly closed when not actually taking your supplement dose.
- Buy them in small bottles, no larger than what you or your household can use in a few months.
- Pay close attention to the expiration date, and discard them after this date.
- Never heat or cook with them.
In addition, check their smell and taste frequently; rancid oils tend to be unpleasant tasting and bitter. Fresh flaxseed oil has almost no taste, while rancid flaxseed oil smells kind of like an oil painting. Any oil that develops these off tastes and odors should be discarded without taking any more.
A note to you frugal people out there: Since omega-3 nutritional oils spoil easily and need special processing and packaging, they tend to be much more expensive than grocery-store cooking oils. If the taste is only slightly off or the expiration date wasn’t that long ago, you might well be tempted to keep taking the oil; after all, it was awfully expensive. But you can pay with your wallet or pay with your health. Do yourself a favor and toss the oil and get a new bottle.
What about oils in capsules?
Oil supplements, such as fish oils, are sometimes put into gel capsules to make them easier to take, and doing so reduces the unpleasant tastes associated with such oils. Flaxseed oil is also often sold in gel capsules. Putting oils into gel capsules also helps keep them fresh longer.
But oils in capsules, like oils not in capsules, is still subject to rancidity. The difference is that oil in capsules, by design, can’t be tasted, and so rancidity is unlikely to be detected. If you have such capsules, it’s a good idea to keep them refrigerated, abide by the expiration date, and open one occasionally to smell and taste for rancidity. If one capsule is rancid, they all are, so discard the whole lot. Alternatively, take the whole oil from the bottle so the distinctive taste and smell of rancid oil is readily detected.
Are there other supplements that can present these problems?
Vitamins A, D, E, and K are all oil-based. They are typically placed in gel capsules with omega-3 oils, since these vitamins need oil in the diet to be assimilated and used properly. They should, in fact, be taken along with additional nutritional oil. But these vitamins can also go rancid because of the oil in the capsule, and the same precautions should be taken with these as with the oils in capsules: keep them refrigerated, use them by the expiration date, and open and check the capsules on a regular basis.
