Often, good thoughts come together when I run. This morning when I started to climb the hill to the house I tasted the sweat that was beading on my face. When I got to the top of the hill enough thoughts had come together to make an idea.
These are the thoughts:
My sweat is super salty, more salty than I can remember it being in the past.
I have been eating more salt recently as I have lowered my dietary carbohydrate intake.
My skin is so much better when I exercise and when I sweat.
My skin has been a lot better recently.
Is dietary salt linked to the amount of salt I can sweat out?
Over the last 30 years Western culture may have shifted to alter the quality and quantity of salt intake because of the widespread recommendations to keep salt intake to a minimum.
The PURE study found that people who eat the least salt have the highest mortality. The level of salt intake associated with the lowest mortality was between 3-5 grams a day.
Dietary intake of salt is physiologically necessary for life.
Salt has had a bad rap but is regaining its ‘proper’ place – Dr James DiNicantonio wrote a book called ‘The Salt Fix’ and writes regularly about salt. I haven’t read it yet.
Salt is antimicrobial and therefore can prevent infection.
We use salt mouth washes for emerging wisdom teeth and salt solutions for infected ear piercings etc.
Common skin complaints such as acne, eczema, psoriasis are characterised by a continued cycle of inflammation and infection.
Does salt intake have a role in skin complaints?
Is the increase in prevalence of skin complaints perhaps contributed to by a decrease in salt intake?
How do we measure salt in the body – serum electrolytes only gives insight into the salt in the blood which is finely regulated. Perhaps we should measure salt in the tissues to gauge a persons’ salt stores?
Would ’tissue salt’ correlate with skin complaints?
Here is the idea:
Salt intake has reduced over the previous 20+ years secondary to guidelines, while skin complaints have increased. The antimicrobial function of salt may have vital roles in manipulating the compositions of flora on the skin. Tissue levels of salt may impact the amount of salt that can be lost onto the skin during sweating. The effects of salt restriction are to deplete the body’s reserve of salt to increase the susceptibility of the skin to infection and inflammation, resulting in skin diseases.
What’s been done already?
In 1972 a letter was written to the JAMA Dermatology by Dr Richard Lennihan describing his observations that teenagers spending time in salt water had better skin than their counterparts who did not play in salt water. Dr Lennihan also gives his recipe for a salt-based aftershave solution that I reckon is better and cheaper than anything you could buy at the pharmacy.
And what about this, by Jantsch et al.? “Finally, we found that increasing Na+ content in the skin by a high-salt diet boosted activation of macrophages in an Nfat5-dependent manner and promoted cutaneous antimicrobial defense. We suggest that the hypertonic microenvironment could serve as a barrier to infection.”
What about the studies that say that salty foods increase acne? This study found that those individuals who ate the most salt in their food had higher rates of acne. This doesn’t suggest that salt intake itself is bad – but perhaps identifies foods that should be avoided. In this study, examples of salty foods were not given but I expect that the foods included on the salty list resembled those on the spicy list; spicy potato chips, spicy corn snacks and hot sauce. What would be interesting to see is the composition of each individual’s diet with respect to the intake of processed food. Despite this, the conclusion of the study was that people who suffer from acne should just decrease their intake of NaCl – while I expect it is probably better to avoid foods that are high in salt, especially those ‘processed’ foods that rely on salt levels to preserve them.
So what’s the conclusion?
The PURE study suggested that if you have healthy physiology and kidneys, upping your salt intake won’t have worse effects than having super low salt intakes. In their population studied, 3-5 grams was the optimal amount, however, this doesn’t cater for endurance athletes or people who lose lots of salt in their sweat.
Jantsch et al. wrote that higher salt levels in the skin can cultivate an antimicrobial environment, and salt influences the behaviour of immune cells to become pro-inflammatory. This means that in a health immune system, salt is a positive influence on immunity. Jantsch et al. also cited evidence that high salt diets can worsen inflammatory or autoimmune diseases, which although alarming, makes sense – in an immune system where function is dysregulated and T cells are uninhibited, further activation of the pro-inflammatory nature of T-cells will worsen disease activity. In these cases, a general guidance of increasing salt intake does not fit. Proceed with caution!
One common recommendation to gauge salt intake is to eat salt on its own and see if it tastes good – dab your finger in some salt and lick it. Don’t go eating salted cashews to gauge your salt level because I’m sure it will end with an empty pack of salted cashews and no better understanding of your salt status 😉
As an alternative, this letter suggests that topical application of salt to affected areas of skin may be a way to benefit the skin but avoid the systemic effects of eating higher amounts of salt.
Maybe you could try the salt aftershave created by Dr Lennihan, and let me know!