Clarifying omega-3: something fishy here

It’s time to tackle the job of unravelling some of the mysteries surrounding nutrition. It always comes as a bit of a surprise to me that nutrition has become mysterious, but when people are buying exercise clothing made with seaweed because they believe that seaweed will somehow confer enhanced vitamin status, then something has to be done about it.

So, first things first. No amount of seaweed woven into your garments is going to translate into vitamin absorption through your skin. To achieve optimal nutritional status, you have to eat properly…and possibly take a couple of supplements. Notice the word “possibly”. You’ve read my ranting about vitamin D in previous blogs so I’ll make this brief and to the point: if you’re not wintering in the tropics and exposing your body to fifteen minutes of un-compromised sun exposure (no sun screen) every day, then you should be taking at least a daily 1000 IU supplement of vitamin D. Sunlight and fortified milk are your only reliable sources of this vitamin and even if you drink a litre of milk every day you’ll only get 400 IU. A word to the wise should be sufficient.

The next supplement I think you should consider is one containing omega-3 fatty acids. Actually, it’s not the omega-3s that you need so much as the DHA and EPA (docosahexaenoic acid and eicosahexaenoic acid; aren’t you glad you asked) that are derived from marine sources. Notice again that I said “consider”: perhaps you’re among the very few people that routinely (two to three times per week) eat fatty fish like mackerel, salmon, herring and sardines. You might also consume eggs and dairy products that are enriched with marine-source omega-3, in which case you probably don’t need a supplement.

But now another wrinkle adds to the confusion…what is the source of your omega-3s?
It seems that some food companies are failing to distinguish between the different types of omega-3s: DHA, EPA and, a third entry ALA (alpha-linolenic acid). EPA and DHA are obtained from marine sources like the aforementioned oily fish (DHA can also be derived from microalgae). ALA, on the other hand, comes from plant sources such as flaxseed. So, you well might ask, what’s the big deal. And the big deal is simply this: EPA and DHA are significantly more bio-available (ready to be absorbed by the body) when they come from fish than when they come from plants. While flaxseed is certainly a “source” of omega-3, the ALA it contains is simply a precursor to DHA, in other words, it has to be converted by the body before it can be used, and in that conversion process a lot of the benefits are lost. Some labels simply refer to omega-3 without stating the source or type. In one example, an analysis of a product found it contained less than 0.002 per cent EPA and DHA. The type of omega-3 found in fatty fish is the best kind. There’s very little doubt that EPA and DHA are vital for our hearts, brains and immune systems. Some food labels are mixing together things that have different biological effects. Omega-3 from vegetable sources is very different and doesn’t have the same health benefits. Whether ALA has any benefit aside from its limited convertibility to DHA and EPA is a horse of a different colour. You should aim for roughly 450 mg of DHA/EPA combined, per day. A serving (3 ounces) of fatty fish will give you about 2000 mg, hence the need for consumption only 2-3 times per week.

Well, having said all that, just what benefits might one expect from these omega-3s? As I’ve mentioned, there is strong evidence that they will help the heart, brain and immune system. There is recent research showing that omega-3s are associated with reduced progression of coronary atherosclerosis, lowered triglyceride levels, lowered blood pressure, and protection against arrhythmia. In addition there has been shown to be an association between increased intake of omega-3s and reduced risk of colorectal cancer and depression. There’s even evidence that intake of omega-3s can reduce the risk of age-related macular degeneration.
Some of these findings might in fact be related to the ratio of omega-6 to omega-3, which has been discussed in this space already. The message is clear: try not to consume too much vegetable oil, and if you don’t eat fatty fish take fish oil supplements. And always read the labels!