Is flax necessary for a healthy diet

hard to chew (photo: HealthAliciousNess via Flickr)

Flax is everywhere.  And because it’s touted on hundreds of food labels in a positive way, consumers start to believe it’s important and healthy.  It’s another fascinating example of how nutrition beliefs develop, not from evidence but from marketing.  Push some ingredient enough, brag about it on food labels, and people will believe.  So what is the evidence for flax?  Is it all that healthy?

Flax in food is from flax seeds, from the plant that gives us linen and linseed oil.  Linen fibers from the plant have been used to make cloth for thousands of years.  The seeds are high in oil, and linseed oil has been used for a long time in paint and varnish.  The whole seed makes an excellent high protein animal food.  Widespread use in human food is quite recent, and one key reason is the high content of omega-3 fats in the flax seed oil.  Since flax is a plant, the omega-3 is the far less biologically active alpha-linolenic acid, which makes up almost half the fats in flax seed.  For this reason, if you buy flax oil, you might notice is smells a bit fishy.  That’s from the high omega-3 fat content.  Alpha-linolenic acid is highly reactive to heat and oxygen, so it’s not an oil you would use for frying.  You should keep any flax oil or flax seeds you buy in the refrigerator, away from light and heat.

The omega-3 content is the primary reason flax is being touted as a health food, despite the fact that plant-sourced omega-3 is much less biologically active.  The 18-carbon alpha-linolenic acid fatty acid chain has to be elongated to the 20 or 22-carbon chain omega-3 fats, and that metabolic process is not very efficient.  But it’s a lot easier and a whole lot cheaper to put flax into a food product in order to brag about omega-3 content than it is to put salmon or sardines or purified EPA or DHA in the same product.  Imagine a snack bar that touted “contains salmon!” on the package.

Another nutritional plus for flax is the high fiber content.  A mere tablespoon of ground flax seed has almost 2 grams of fiber.  So sprinkling it on cereal or adding it to bread or energy bars boosts the fiber content, creating another nutrition marketing opportunity.

Back to the question: is flax all that healthy?  It’s certainly got some benefits, with high fiber and signifiant plant omega-3.  If you’re a vegan, this might be a key source of omega-3 fatty acids.  But is it some miracle food?  No.  You can get more biologically active omega-3 from animal sources, like salmon or sardines.  You can get fiber from vegetables, fruits and other whole grains.  If you think the omega-3 and fiber from flax justifies a diet of granola bars, you’d be wrong.  If you think flax is a good selling point for pricey cereals, well that’s your choice.

The only drawback for flax is the taste.  In high amounts, it can be distinctly fishy (it’s the omega-3).  People can get used to the taste, and have figured what the right amount is to add to their oatmeal or yogurt smoothie, to avoid strong flavors.  If you buy flax seed or flax seed meal for home use, be sure to refrigerate it.  Speaking of which, here’s another issue: whole flax seed is not well digested.  Much as fresh corn is not well digested, because people don’t chew it up completely, tiny flax seeds may just pass right through your system.  You won’t get any benefits from the omega-3 or fiber if you don’t chew them up properly.  If you think large soft corn kernels are a problem, tiny hard flax seeds are going to be even more of a problem.  The solution is to purchase ground flax seed meal and use that.  But because it’s been ground up, it’s more exposed to oxygen, making it even more important to keep it in the refrigerator.

Find some flax recipe ideas here.

The podcast concludes with a discussion of a recent article on “sedentarism”, a newly recognized public health threat of sitting too much.

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