I am an avid reader of your newsletter, thank you for all your efforts, they are much appreciated I’m sure by all who read it.
I am 28 years old, very fit and active, and someone who pays much attention to things I eat (apart from the usual chocolate and cakes now and then). I limit my saturated fat intake, and although I’m vegetarian, I eat more than enough protein from dairy, soy and legumes. The only thing that I don't concern myself with is sodium. But then again my blood pressure has never been a problem - always 110-120 / 70-80. Is this a mistake on my part?
So I guess my central question is this - does the research suggest that high levels of sodium cause high blood pressure or is it the case that reducing your sodium intake when you already have high blood pressure helps on reducing it? Or as logicians would ask: Does A cause B or does notA cause notB?
As far as I was aware, salt and hypertension were intimately connected, but in recent weeks I have been hearing contrary study results. Then today I was reading this interview, and this one, both from Scientific American, and things confused me even more.
Would love to hear your take on things. Thanks for this,
No simple matter Farid. In one of your articles, Marion Nestle's comments have been echoed by many. If you get people to reduce their salt by 10-20% you may not see any effect on blood pressure. Some people may need to reduce their salt intake by 50-80% to have an effect on blood pressure. That is difficult because most salt is added by food manufacturers and salty food doesn't often taste salty, such as bread & cornflakes. Hunter-gatherers ate about 200 mg of salt each day; westerners eat 3000-6000 mg a day, that is, about 15x - 30x as much as we were designed to consume.
Also remember that a high salt diet increases calcium losses via urine, so even if you cut back on salt and there is no effect on blood pressure, it is still good for your bones.
Anyway, there will always be debate. Why are there no clear-cut answers?
1. Because, in nutrition, you can't increase/decrease a nutrient/component in food/diet without changing many other things in a free-living human. Eating less salt is likely to mean eating more fresh foods, such as fruit and vegetables. Is any response due to less salt or more vegetables?
2. We all have differing genetic backgrounds.
3. We all respond differently to our environment, including the food we eat.
I wish I could provide a simple answer. I can't. Just reading the articles you have found will give you some insight as to lack of agreement, one key reason is because we can't find westerners on a truly low salt diet to compare with those on a high salt diet, so we may just be comparing those with a very high salt intake to those with a high salt intake.
The August 2011 edition of GI News also discusses the influence of food and lifestyle on our blood pressure. Scroll down about two-thirds for the article by Alan Barclay.
My view? Keep doing what you are doing. Eat well. Don't add salt to food. Choose lower salt varieties of commercial foods. No harm. It may be better for you, who knows?