Humans crave the taste of salt. We like it because salt is essential for our survival, so a salt craving is an evolutionary drive hard-wired into our brain’s reward system. Seeking salty and sweet tastes has kept the human species alive for millennia. Today, the once scarce resource of salt is plentiful, and humans now risk consuming too much. Indeed, there is a drive in many corners of the world to reduce the amount of salt in our food. The fact that salt enhances the natural flavours in food – along with its ability to stimulate specific taste receptors linked to neural pathways in our limbic system and trigger a dopamine dump – has led food producers to add it liberally to make their products more appealing. Now, an increasingly health-conscious consumer base is turning towards low-salt options. Reducing sodium content in foods has become one of the biggest public health initiatives of modern times. Excessive salt consumption is recognised as one of the most powerful factors contributing to non-communicable diseases – among them cardiovascular disease and chronic kidney disease.
A vast body of research suggests that salt intake in many developing countries has increased sharply over the years. Some studies suggest that it has already reached a level more than double the 5g per day limit recommended by the World Health Organisation (WHO). The WHO has openly stated that more than 20% of the world’s population is hypertensive – affected by high blood pressure – and the condition, which is one of the leading causes of premature death, is closely related to a high level of sodium intake.
The WHO has set global non-communicable disease (NCD) targets, among which is the reduction of salt/sodium intake by 30%, and a related target of reducing the prevalence of raised blood pressure by 25%.
The challenge for food companies is to find a way of maintaining that salty taste and flavourenhancing effect while cutting out the sodium that comes with traditional salt. For many, the answer seems to lie in umami – a flavour-enhancing ingredient found in dishes all over the world – but that brings its own set of challenges.
Is umami the answer?
Umami is everywhere. Described as the fifth basic taste – after sweet, sour, salty and bitter – it is not exactly interchangeable with salt in terms of flavour, but it does hit the same spot. A savoury taste that enhances flavour, it is caused by glutamates and nucleotides found naturally in many common foods – among them mushrooms, tomatoes, cured meats and aged cheeses. A marker for protein, it is frequently used to enrich flavours in both Western, Latin American and Asian diets.
Wherever it is found, it is the taste of glutamate – one of the most common amino acids found in nature.
Worcestershire sauce, ketchup, Marmite spread and Oxo stock cubes – all popular in the UK’s diet – are full of umami. So, too, are the dried meats that make up an important constituent of South American cuisine and are full of glutamate. Italian and French food have it in abundance in their use of cheeses, mushrooms and tomatoes, and bouillon and consommé in French cuisine specifically.
Sea vegetables – such as seaweed and sea lettuce – have high concentrations of glutamate, and are historically components of coastal communities in the UK and the Nordic countries. Many North Atlantic kelp varieties are very high in glutamate.
Yet umami is most associated with the Asian diet. From fish sauce and shrimp paste to soy sauce and miso, from kimchi to seaweed, umami is everywhere. Korea has kimchi, the doenjang soybean paste, and many fermented seafood dishes. In China, soy sauce and fermented beans are commonplace. The Japanese culinary tradition, however, is the one in which umami is most central, not only because of the prevalence of fermented foods – miso is itself a fermented soybean paste – but also tamari, tempeh, and a host of other ingredients.
Dashi – the traditional soup stock that is a cornerstone of Japanese cooking – is an umami-rich liquid base for many noodle dishes and stews. It is typically made by steeping or simmering kombu (kelp), katsuobushi (dried bonito flakes), shiitake mushrooms or other dried ingredients in water to extract their natural flavouring compounds.
So, we are all familiar with the taste of umami, whether it is in seaweed, Marmite, ketchup or a more exotic dish, but how does it stand to help with initiatives to remove excess salt – sodium chloride – from our diet?
Part of the answer lies in the most common umami seasoning – monosodium glutamate (MSG) – which contains two-thirds less sodium than table salt. To be more specific, MSG contains approximately 12% sodium compared with the 40% sodium content of traditional salt. Consequently, when it is used as a partial salt replacement, MSG can result in a significant reduction in the overall sodium content of most foods.
While umami does not exactly mimic the taste of salt, it has a similar flavour, plus it has the effect of intensifying the perception of other flavours – including a salty taste – and this is the crucial effect that enables it to deliver the desired flavour with less sodium.
A powerful tool to tackle sodium consumption
Salt reduction initiatives around the world are considering many options, including the direct substitution of potassium chloride (KCL) for sodium chloride (NaCl). Each one has its advantages and its drawbacks. In the case of KCL, it is reliant on the supply chain for potash – a varied group of water-soluble, potassium-bearing minerals often used as a fertiliser. Also, some consumers report a bitter metallic taste, and the risk of hyperkalaemia (high potassium levels) makes it potentially dangerous for people with kidney disease, heart failure, or who are taking certain blood pressure medications.
A recent study, ‘Reducing salt intake with umami: A secondary analysis of data in the UK National Diet and Nutrition Survey’, attempted to quantify the amount of salt intake that could potentially be reduced by using umami substances, including glutamate, inosinate and guanylate, without compromising taste.
Using data from 1,834 adults aged 20 years and over from the UK’s National Diet and Nutrition Survey, the study suggested that replacing salt with umami substances could help UK adults reduce their daily salt intake by 9.09–18.59%. This equates to 0.45–0.92g/day of salt reduction.
The researchers concluded umami substances could, therefore, serve as one method for the UK government to encourage salt intake reduction, particularly in the context of food product reformulation, as 80% of salt consumed in the country comes from processed foods.
In Japan, the Smart Salt Project intends to tackle the conundrum of the country’s cuisine being essentially very healthy apart from the fact that it is very high in salt. According to the National Health and Nutrition Survey from Japan’s Ministry of Health, Labour and Welfare, over 80% of the Japanese population exceeds the daily recommended salt intake. Moreover, that was before the same ministry’s Dietary Intake Standards lowered the daily recommended salt intake for adults by 0.5g, to no more than 7.5g for men and 6.5g for women.
High sodium intake is a crucial risk factor for chronic diseases, and it has been a heavy burden in Japan for decades.
A 2023 study, ‘Modelling of salt intake reduction by incorporation of umami substances into Japanese foods: a cross-sectional study’, estimated that it would be possible to reduce the Japanese population’s salt intake by up to 2.22g – or 22.3% – without compromising the taste of food by substituting salt with umami substances.
So, where is the catch? Well, MSG – the purest and most concentrated form of umami flavour available – brings its own health concerns. Though classified as safe by the US Food and Drug Administration (FDA), it is still shrouded in controversy, as a significant number of consumers report side effects – nausea, migraines, sweating and elevated heart rate. No clear link has been scientifically established, but the narrative is hard to shake. Food producers can use MSG without breaking any rules, but they may have to overcome a negative public perception of the ingredient. They can also turn to natural sources of umami as alternatives, incorporating edible seaweed or certain fermented ingredients, to reduce sodium levels.
So, who is leading the way? Kikkoman soy sauce – naturally rich in umami due to its fermentation process – yeast extract Marmite, and any brand of Worcestershire sauce are among the wellestablished products that have made umami flavours familiar. Frito-Lay puts the success of its Spicy Sweet Chili Doritos down to the blend of soy sauce and MSG that gives them such a distinctive taste. Ingredients suppliers in Japan and Europe are coming out with salt substitutes that leverage the umami effect, so it is up to the big food producers to take advantage of them.
