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On May 14, 2013, the National Academies’ Institute of Medicine released the report “Sodium Intake in Population: Assessment of Evidence” (Download the full IOM report here). The National Academies’ press release stresses that the average American adult’s daily intake of 3400mg or more of sodium is definitely too high, just as we’ve been hearing about for years. However, it does put into question whether there is any scientific evidence to support limiting it to 1500mg or less, as advised by the American Heart Association.

The IOM report does not recommend a particular level or range of sodium (they were not tasked to do so), but concludes that there is not enough evidence to determine whether a 1500mg limit is better or worse than a 2300mg limit. The press release also notes that “lowering sodium intake too much may actually increase a person’s risk of some health problems” without quantifying what “too much” is. It does not say that 1500mg is too low, merely that there is insufficient evidence to claim it is a better limit than 2300mg.

As it happens, I have been gathering data on my sodium consumption since the beginning of March. By my reckoning, my average daily sodium intake over this time period has been about 1600mg per day.

Daily Sodium Intake

I have also gathered samples of blood pressure readings both on the DASH diet and a year ago, when I was on the same blood pressure medicine as now but not on the DASH diet. Analyzing this data, I find that there is very strong support to conclude that my blood pressure has decreased significantly, from an average of 128/75 (before the DASH diet) to an average of 118/72 (on the DASH diet).

Before DASH Diet On DASH Diet
Average 128/75 118/72
Minimum 107/60 93/59
Maximum 140/82 140/87
Standard Deviation 9/5 11/6
Standard Error 1.6/1.0 1.5/0.8
Number of BP measurements  28  55

Here are some box-and-whiskers plots of the systolic pressures (the first number in a blood pressure reading) and the diastolic pressures (the second number in a blood pressure reading) in my samples:

Systolic Pressures on and off the DASH Diet Diastolic Pressures on and off the DASH Diet

In upcoming posts I plan to elaborate on my data analysis, to support my conclusion that my blood pressure has improved while on the DASH diet. Obviously, your mileage may vary, and blood pressure is not the only health issue one needs to be concerned about, but as for me, I will continue with the DASH diet.

I haven’t tried aiming for a 2300 mg per day consumption — I went straight for the 1500 mg limit — so I can’t provide any insight into the 1500 vs. 2300 debate. It’s tempting to try it for a while, though, just so I can have more fun with data…