Studies show...so what?

Something that has concerned me for quite some time now is the abundance of nutrition-related headlines that are often followed by a conflicting headline. For example, “Dietary cholesterol is bad for you”…and then, “Oops, it’s not the cholesterol that will do you in, it’s the saturated fat!” You get my point. I’m worried that people will have little faith in reports about nutrition research and tune out the good advice they mostly receive.

You’ll notice that I said “mostly”. Unfortunately there’s been a tendency for the media to jump to conclusions on trendy nutrition topics and they report on issues before all the findings are in. A couple of cases in point surfaced recently when some back-pedalling was called for on soy and omega-3 fatty acids.

To refresh your memory (although unless you’ve been on Gilligan’s Island for the last 10 years you couldn’t have missed the story), soy gradually gained the reputation of being able to lower cholesterol and risk of heart disease; reduce menopausal symptoms, cut breast-cancer and prostate cancer risk; and lower your chance of developing osteoporosis. Many people would confide to me that although they weren’t fond of the taste of various soy products they were going to eat them anyway because they’re so “good for you”. But where was the evidence? Granted, some observational studies found a possible association between soy and some of the conditions mentioned, but the linkages were often dubious. Even in terms of cholesterol-lowering, the amount of soy needed to be consumed to bring about a significant drop in cholesterol was enough to choke a horse. The Food and Drug Agency in the U.S. was even persuaded to let soy-food manufacturers claim on their label that soy products might cut the risk of heart disease. (a little side note here: always be suspicious of any food or substance that claims it “might” do something; remember that “might” carries with it the implied “might not”).

Anyway, long story short: The American Heart Association reviewed ten years worth of studies on the benefits of soy and came up with results that pretty much discredit its hallowed reputation. In and of themselves, soy foods won’t deliver any of the health benefits that have been chalked up for them. None of this is to say that soy is not a fine food…just don’t expect miracles from it. The argument has been made that even if soy won’t do all that’s been claimed, if you’re eating soy in place of meat, then that’s a good thing. Personally I think that’s another bit of hype that will eventually be shot down. Sure, some people consume meat to excess (nobody needs a 24 ounce steak hanging off their plate), but the notion that meat is “bad” is just plain wrong. Along with the protein it supplies (which you could get from a combination of plant foods), it delivers extremely important minerals that are hard to find in a meat-free diet.

The next case of jumping the gun has to do with omega-3 fatty acids. These little jewels, found primarily in fatty, cold-water fish like salmon, mackerel, and herring but also in flax seed oil, were justifiably cited as useful weapons in the fight against heart disease. Somewhere along the line they also became thought of as being able to prevent, or reduce the risk of, cancer. Again, a major investigation that looked at many years worth of research found that there simply was no connection between the amount of omega-3s you consumed and your chance of developing cancer.

On the other hand, there is a very persuasive amount of evidence that pregnant and breast-feeding women who consume omega-3 fats are helping the brain development of their infant. Improved cognitive function in the elderly has also been cited as a positive effect of omega-3 consumption. So…am I a supporter of omega-3 fatty acids? Yes, whether in the form of fatty fish or fish oil supplements. But…. Like many other things in nutrition, it’s not as clear- cut as it might seem.

To begin with, the specific omega-3s (DHA and EPA) have to make their way to your bloodstream. One of the obstacles on this journey is the omega-6 fatty acid (specifically linoleic acid found in vegetable oils). Please don’t let your eyes glaze over at this point; this is important. When the ratio of omega-6 to omega-3 is in the 10 to 1 range as it is in North America (ideally it should be about 4 to 1), the omega-3s just don’t become assimilated. So not only should you be consuming more fatty fish or fish oil, you should take care not to consume excessive amounts of vegetable oil or the products made with them. Olive oil has the least amount of linoleic acid, followed by canola…so that’s what I recommend.

To sum up, then, soy is an alright food but doesn’t have the health benefits claimed for it; and omega-3s are great for a number of health benefits but won’t reduce your risk of cancer. Stay tuned!