"Omega-3 deficiency causes 96,000 US deaths per year, say researchers". That was the headline of a recent NutraIngredients article (1). The title highlights one of the more surprising finding of a study on "The preventable causes of death in the United States: Comparative risk assessment of dietary, lifestyle, and metabolic risk factors" (2).

A group of researchers set out to identify the lifestyle, dietary and metabolic health risk factors responsible for the greatest number of premature and preventable deaths in the United States. Metabolic risk factors are physiological indicators like blood pressure, glucose levels, LDL-cholesterol, etc. For any given risk factor to be included in their analysis, a number of conditions had to be met:

• it had to be a known cause of disease-specific mortality,
• a quantitative relationship between magnitude of risk and likelihood of death from a specific disease had to be available from observational or controlled studies,
• the risk factor had to be controllable through lifestyle changes or medical intervention, and
• representative risk factor distribution data for the general population had to be available.

If one knows the distribution of a given risk factor in the general population, and if the relation between its magnitude and the probability of disease-specific death from that risk factor can be quantified, then one can estimate the proportional reduction in the number of deaths that could be achieved by eliminating that risk factor. With this information it is then a simple matter to estimate the actual number of premature deaths that could be avoided by eliminating that risk factor; it is the product of the proportional reduction in the number of deaths and the actual number of deaths from that disease.

Here are the author′s estimates (2) for the number of deaths that could have been prevented in the U.S. in 2005, if the following twelve risk factors had been eliminated (confidence intervals in parentheses):

• smoking 467,000 (436,000 - 500,000)
• high blood pressure 395,000 (372,000 - 414,000)
• overweight-obesity 216,000 (188,000 - 237,000)
• physical inactivity 191,000 (164,000 - 222,000)
• high blood glucose 190,000 (163,000 - 217,000)
• high LDL-cholesterol 113,000 (94,000 - 124,000)
• high dietary sodium 102,000 (97,000 - 107,000)
• low dietary omega-3 fatty acids from seafood 84,000 (72,000 - 96,000)
• high dietary trans fatty acids 82,000 (63,000 - 97,000)
• excessive alcohol use 64,000 (51,000 - 69,000)
• low intake of fruits and vegetables 58,000 (44,000 - 74,000)
• low dietary polyunsaturated fatty acids (PUFAs) 15,000 (11,000 - 20,000)

Not surprisingly, smoking and high blood pressure were found to be by far the most serious risk factors for premature death. The high health risk posed by obesity, physical inactivity and high blood glucose had to be expected as well. The most surprising finding, though, has to be the importance of omega-3 fatty acids from fish. A lack of EPA and DHA in the diet turned out to be nearly as large a risk factor as high LDL-cholesterol or sodium levels, and more of a risk than trans fatty acids and low intakes of fruits and vegetables.

Some of the variables in this list seem like strange choices. For example, blood pressure and sodium intake aren′t independent of one another; increased sodium intake increases blood pressure. Similarly, there has to be a connection between overweight-obesity and physical inactivity. On the other hand, a number of well-known risk factors — caloric intake, triglyceride and HDL-cholesterol levels — were excluded, because their causal connections to specific diseases are less well established. Vitamin D is another surprising omission.

Be that as it may, these considerations are unlikely to put the omega-3 results in question. So, if you don′t like fish, supplement with EPA/DHA. It′s one of the most affordable and effective health measures you can take.

Sources:

1. Shane Starling. Omega-3 deficiency causes 96,000 US deaths per year, say researchers. NutraIngredients June 26, 2009.
   http://www.nutraingredients-usa.com/content/view/print/252050
2. Danaei G, Ding EL, Mozaffarian D et al. The preventable causes of death in the United States: Comparative risk assessment of dietary, lifestyle, and metabolic risk factors. PLoS Medicine April 2009;6(4).
   http://dx.doi.org/10.1371/journal.pmed.1000058