Fishermen tend to embellish the size of their catch, hence the expression “fish tale” for exaggerated stories like the ones making the rounds about tilapia, a fish that is increasingly showing up on dinner plates. Indeed, it is now the most widely consumed fish after salmon and tuna. Typically, headlines scream about tilapia being “Poop Fish,” “Worse Than Bacon,” “No Better for You Than A Doughnut” and that it is “ Like eating a rat!!” Relax. Tilapia will not poison you. You are better off eating it than bacon or doughnuts. As far as rats go, there are no studies on their nutritional value since few humans make a habit of dining on the rodents. But I suspect tilapia tastes better.
The increasing popularity of tilapia is due its mild taste and the relative ease with which the fish can be raised on fish farms, leading to a lower cost. Although there are tilapia farms in North America, most of the tilapia consumed are imported from Asia, with China being the main producer. The “poop” connection arises from some unscrupulous operations that have been identified there. Tilapia in the wild feed on algae, but on farms they are reared on corn or soybean meal. However, when no other feed is provided, they will eat “poop.” There have been instances where fish farms in Asia were found to be feeding poultry, sheep or hog manure to tilapia. While this does not mean that eating these fish is tantamount to eating poop, the practice does increase the risk of bacterial contamination and the need to treat the fish with antibiotics. It isn’t clear just how widespread this practice is in Asia, but it doesn’t occur in North America where the quality of the water in which tilapia are raised is also carefully monitored.
The nonsensical “worse than bacon” and “worse than doughnuts” stories can be traced to a publication in the Journal of the American Dietetic Association back in 2008 in which researchers from Wake Forest University reported on determining the ratio of omega-6 to omega-3 fatty acids in a variety of fish. This is of interest because omega-3 fats can reduce the risk of irregular heart rhythms, ease inflammation and inhibit the formation of blood clots while the omega-6 versions have been linked, albeit somewhat controversially, with increased inflammation, a contributing factor to chronic conditions such as heart disease and diabetes. In theory then, the lower the ratio of omega-6 fats to omega-3s, the less the likelihood of triggering inflammation. Based on this view, the Wake Forest paper somewhat unfortunately noted that “all other nutritional content aside, the inflammatory potential of hamburger or pork bacon is lower than the average serving of farmed tilapia.” As one might expect, this observation spawned a number of scary media accounts.
Of course, it is totally unrealistic to “put all other nutritional content aside.” Hamburger and bacon contain far more saturated fat and cholesterol than tilapia, and are burdened with other issues such as nitrite content and the formation of various carcinogens on cooking. Furthermore, the role that omega-6 fats play in health is complicated. The main omega-6 fat in the diet is linoleic acid, which in the body is converted into arachidonic acid that then is further converted into a variety of compounds, some of which promote inflammation while others have an anti-inflammatory effect. Also to be considered is the ability of omega-6 fats to reduce LDL, the so-called “bad cholesterol” and boost HDL, the “good cholesterol.” Indeed, some studies suggest that the decline of heart disease in North America since 1960 can be attributed to replacing saturated fats with omega-6 fats. Basically then, the degree to which the omega-6/omega-3 ratio is to be regarded as a significant risk factor is unclear.
As far as doughnuts go, their sugar and saturated fat content trumps any worry about unsaturated fat ratios. It also noteworthy that many “healthy foods,” such as nuts and grains have a considerably greater omega-6/omega-3 ratio than tilapia. There is far more to determining the “healthiness” of our diet than this ratio. While it may be meaningful in the context of the overall diet, it doesn’t have much meaning when looking at individual foods.
It is true that wild tilapia eating algae rich in omega-3 fats have a more favourable ratio than farmed fish that are fed a diet of corn and soy in which omega-6s predominate. Like people, fish are what they eat. It is also correct to say that other fish, such as salmon and tuna, have far more of the beneficial omega-3s than tilapia. On the other hand, since tilapia do not eat smaller fish, they have a lower mercury content than most other fish since mercury gets concentrated up the food chain.
Given that male tilapia grow larger than female, they are more profitable to produce. Interestingly, tilapia are actually born genderless and can be made to develop into males with the addition of methyltestosterone to their diet for a short time after birth. By the time the fish are marketed at the age of six months there is no residue of this hormone in the flesh. There is some concern about releasing wastewater from facilities where hormones have been used, but gravel and sand beds can filter out any methyltestosterone. In any case, in North America such hormone treatment is rarely used.
The bottom line is that farmed tilapia can certainly fit into a “healthy” diet, and provide a good alternative to meat. If a choice is available, North American tilapia is a better bet than fish that are imported from Asia. Given that in about twenty-five years we will be looking at a world population of 9 billion, fish farming is going to take on greater and greater importance. It is unfortunate that some people will shy away from eating tilapia because of the clutter of fish tales about its risks to health.