If the CEO of Twitter begins his day with a glass of lemon and Himalayan salt water, surely this must be a good idea, right? It sounds simple enough: rehydrate with a little salt and lemon juice to get the metabolism going, and restore the mineral salts we need to get our body ready for the day ahead. Hmmmm maybe, but it also may not be doing that much at all…

Let’s take a closer look at any science that justifies and explains the daily habit recommended by the billionaire who fasts for up to 22 hours and walks 8km to work every day.

The lemon

There is no doubt that starting the day with a glass of water is a good idea. Few people drink enough fluid on a daily basis to keep optimally hydrated, and most of us could do with a big glass of water when we wake up before we start downing the coffee.

Adding lemon to the mix is not a new idea. For some time there has been many a diet that recommends adding lemon juice to the water with the claim that it will support fat burning. There is even an entire diet based around drinking lemon water. It does need to be said, however, that there is no evidence to show that drinking lemon water enhances fat burning.

It may make the water taste slightly better, it may add a little Vitamin C and it definitely makes the water slightly more acidic (which isn’t great for our teeth), but it will not increase metabolism or promote fat burning.

The salt

Now onto the most interesting addition to Jack Dorsey’s water – the salt. In dietary terms, salt is not usually considered a healthy addition to our diets. The average person eats much more salt than they need thanks to diets rich in processed and fast foods, which generally contain bucket loads of salt for flavour.

Even adding a small amount of salt to food tends to push our daily intake way above recommended intakes of no more than 1500-2000mg a day. The body only really needs 500mg of sodium, or a quarter of a teaspoon of table salt to maintain basic physiological functioning.

So, for the average person, adding some salt to water is a rather odd thing to do.

While some of us may be particularly active and have higher mineral demands, these will be more aptly served with a general electrolyte solution or sports drink, which features all the key minerals involved in fluid balance as opposed to relying on just the sodium chloride found in table salt.

For those with low pressure, perhaps some extra salt is warranted, but these people are few and far between.

You could also argue that there is some benefit for some of us in adding iodised salt into our diets. Australian soil is especially low in iodine, and iodised salt tends to be one of the key ways we get this important nutrient which is crucial for thyroid function. Himalayan salt, as added by Jack Dorsey is not specifically high in iodine. It is lower in sodium overall that regular table salt, thanks to its larger granules, and contains some other minerals including magnesium, potassium and calcium, but not a lot of iodine which could perhaps warrant its inclusion.

The bottom line

For someone like Jack Dorsey, who chooses to fast for a reported 22 hours per day, consuming some salty water may do wonders to give a much needed pep up when overall calorie intake is so low.

For the rest of us who are going to eat breakfast or even lunch in the near future, adding salt to your morning water is not necessary or scientifically justifiable. Water and maybe lemon juice yes, but extra non-iodised salt not so much.

Susie Burrell is a nutritionist. Follow her on Twitter: @SusieBDiet