I love Tokyo. I’m rarely excitable, but even my cold northern exterior thaws a little bit when I get off the plane and onto its neon streets. I’m amazed how different the culture is, the sights, the sounds, and the crazy hidden bars. I adore the food too; all except the time when I ate Kusaya.
It’s difficult to describe the smell this dried fish exudes. It’s like a thousand 10-year-old jock straps covered in anchovies and sheep urine. Great fun if you’re on a day off from touring after having spent the afternoon visiting some hidden drinking dens; less so any other time. Your brain immediately sends a very hard signal to your stomach that putting this stuff in your mouth is a really bad idea. The result is complete repulsion. In a way, this kind of protective mechanism comes in handy, if something smells bad, it’s usually a good idea for our health not to eat it. Our brain’s protective reflex takes the choice out of the equation. That seawater-urine-come-anchovies saltiness of Kusaya was a warning to my tummy, but not everything is so clearly signposted in terms of keeping healthy.
Even though salt is completely essential for life, folks are so sure it’s bad for them that they attempt to avoid it completely. That’s practically impossible of course, as it’s contained in many different foods, but it doesn’t stop people eating bland unseasoned dinners or using lite salt or some other abomination in the name of good health.
Without our brains telling us to avoid it, we need to understand if salt is a goody or baddy in the war against bad nutrition decisions.
Eat salt and your body will retain water to maintain the normal concentration of sodium in your blood. Ever eaten something and felt immediately thirsty? That’s homeostasis in action. The increased volume of water in the body results in a temporary increase in blood pressure before the kidneys get rid of both the water and salt. Sounds bad, but it is temporary, the argument against chronic high blood pressure is clear: increased risk of cardiovascular disease and stroke. This means that a lot of health organisations across the world have concluded that fewer than 6g of salt per day is recommended. Sounds sensible, but look what happens when we go above this magical figure.
- Mascioli et al. (1991) increased salt intake to 5.5g for 4 weeks and saw a significant increase in blood pressure
- He et al. (2013) cut salt intake almost in half, for 4 weeks again, to 4.4g and saw a significant reduction in blood pressure
- However, what is important to realise about these results is the real world effect. A statistically significant change doesn’t count for much if the blood pressure results are still within a normal, healthy, range.
In other studies, we see no change at all. Foo et al. (1998) showed that increasing salt from 4g to a whopping 15g (actually try to eat that much salt, you will not do it) over 6 days showed no increase in blood pressure.
Whilst the changes in these studies don’t amount to much, looking at other aspects of the diets of the people at high risk of heart disease might lead to more clues. Currently, 75% of our salt intake comes from processed food. It’s been shown in the literature that people with poorer diets, tend to be indicative of other ‘unhealthy’ lifestyle factors like a lack of exercise, obesity, and smoking. Seeing as if you’re reading this, you likely don’t fall into those particular camps, so is it worth even worrying about it?
- The Kuna people of Panama eat a high salt, non-processed food diet
- They are completely free of cardiovascular disease and hypertension
- Although the island Kuna eat more salt than the more urbanised Kuna, they are healthier
It’s also highly possible to get too little salt in your diet too. According to a meta-analysis from Graudal et al, extremes on the low and high ends of salt intake result in a greater risk of mortality. The middle ground seems to be somewhere between 6g and 12g per day, which pretty much results in never having to think about it if you have any kind of non-stupid diet. This is echoed in a recent Cochrane review:
there is insufficient power to confirm clinically important effects of dietary advice and salt substitution on cardiovascular mortality
There is no reason to worry about your salt intake, so don’t be afraid of the friendly looking shaker. Losing weight, exercising, and not smoking is all you need to do to avoid high blood pressure.
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