Comments on: The sodium debate: heat or light?

By: Bill Shrapnel

Bill Shrapnel — Thu, 28 Jun 2012 04:24:19 +0000

Are you saying that salt restriction should be managed at the individual level? Should we have no public health strategy? Regards, Bill

By: Bill Shrapnel

Bill Shrapnel — Thu, 28 Jun 2012 04:21:31 +0000

Hello MC.
You are right that manipulating salt is not the be-all and end-all of blood pressure. The original DASH study (Appel LJ, 1997) showed that low fat dairy products and fruits/vegetables were important. The DASH-Sodium study (Sacks FM, 2001) showed that sodium had an independent effect. Replacing carbohydrate with protein also lowers blood pressure. High intakes of alcohol and of course obesity have adverse effects. It’s complicated but it also suggests that there is considerable potential to lower individual and population blood pressures by dietary means. Regards, Bill.

By: Bill Shrapnel

Bill Shrapnel — Thu, 28 Jun 2012 04:20:16 +0000

Hi Rob
I hadn’t seen Taubes’ article on salt. I think it is legitimate for him to ask whether the apparent up-tick in risk associated with low salt intakes is real or an epidemiological aberration, but Taubes just assumes it’s real.
However, by far the majority of people have intakes of salt well above this query zone and are in the area where salt reduction will lower blood pressure. Everything we know suggests that this will bring benefit. Taubes says the final proof is not in i.e. that there is no RCT evidence saying salt reduction lowers cardiovascular events. Fair enough, but as mentioned in my blog this evidence will never be gathered. So we are left asking whether lower blood pressure is better for you than higher blood pressure. I say yes. What do you think? Regards, Bill.

By: M.C.

M.C. — Tue, 26 Jun 2012 12:08:16 +0000

There is definitely a link between a fall in blood pressure, amongst other parameters in blood such as cholesterol, triglycerides, inflammatory factors etc. when there is a reduction in excess calories eaten, whether from carbohydrate or fat. Even if calories are not relevant, a redistribution of carbohydrate, fat, protein ratio in the diet can also significantly improve problems such as high blood pressure and poor blood lipids, etc.

So it’s not just the salt that matters, no. I do think salt plays a large role in cardiovascular disease and blood pressure, but that doesn’t mean that ‘low-salt fixes everything’. For example, people who cut sodium probably also cut foods high in sodium that are also unhealthy and high in calories and fat, such as processed meats, potato chips, fries etc. Simply saying that they ‘cut their sodium improved X’ doesn’t really convince me that salt itself did it all, if their diet changed substantially and had als become healthier overall, eg. no more excess calories or fat, not just lower in salt.

By: Rob Lyons

Rob Lyons — Tue, 26 Jun 2012 10:01:38 +0000

Bill,

I’m sure you’ve seen this Gary Taubes piece from a few weeks ago. He’s more of a salt ‘sceptic’. You seem pretty convinced. What do you think of Taubes on this? I must admit the biggest fall in my blood pressure in recent years was by cutting carbs, not sodium (of the order of 6-7 mmHg).

http://www.nytimes.com/2012/06/03/opinion/sunday/we-only-think-we-know-the-truth-about-salt.html?pagewanted=all

By: ProudDaddy

ProudDaddy — Tue, 26 Jun 2012 09:21:41 +0000

There seems to be far too much medical advice given on the basis of the mean. Blood pressure is a perfect example. I think pretty much every researcher knows that some people are salt sensitive and others aren’t. Based on the mean, everyone gets reduced salt advice. In a perfect world, the salt sensitive would get the greater attention.

Similar things apply to RCT results. Huge standard deviations aren’t even commented on, and plots of individual data points are rare. Then the “proof” is labelled “significant” if there is less than 5% chance of the mean having occurred by random chance.

Hopefully, medicine and nutrition will improve in treating the individual rather than the mean. Otherwise, gluten will remain good food for celiacs (statisically)!

By: Cameron McDonald

Cameron McDonald — Tue, 26 Jun 2012 04:25:37 +0000

Thanks for another well researched post Bill. I understand being a reductionist is an integral part of nutrition science, however, don’t you think that all of this data, out of the context of potassium, calcium, magnesium intakes is just a little stretchy. Similar to the saturated fat replaced with polyunsaturated fat argument, do you think we should be looking at sodium replaced with potassium as the way forward. This one nutrient hypothesis is just fraught with confounders that are very difficult to control for.

By: M.C.

M.C. — Tue, 26 Jun 2012 04:22:55 +0000

I think it depends on the person, their lifestyle and activity levels. For the average person who exercises minimally or not at all, they’re most likely either getting enough or too much sodium in their diet (when otherwise unrestricted). Sodium is everywhere because any food you eat has some amounts of sodium, eg. vegetables and grains, on top of the high intake of commercial breads, cereals, processed foods, take-away foods etc. people eat. I think for the average person low sodium or sodium deficiency is not a general concern (unless they’re ill and cannot keep foods or fluids down) because we get well enough of it.

On the other hand, people who are very active like athletes, or young people who train and work out a lot, who sweat a lot, would apply to the danger of low-sodium theory. If their bodies use and excrete a large amount of sodium, without replenishing it from the diet, then of course there is going to be an imbalance. Sodium deficiency can be very acute and serious, hence the use of electrolyte fortified sports drinks among people who do exercise a lot. This group probably don’t have to worry about eating too much sodium as much as the rest of us are. If you use more, you’ll need more of it, no need to obsess. Rather, they may want to make sure they’re getting enough of it.

Overall a great article. However I don’t think it should be targeted at the general population, but more at those who actually may be at increased risk of low-sodium, such as athletes.