Who doesn’t love soy sauce? That unique combination of tang and sweetness contributes to the characteristic rich flavour of soy sauce. Given its strong umami flavour, it’s unsurprising that soy sauce is commonly used to add extra flavour to a variety of Asian dishes.
But whether you’re adding soy sauce to stir fries, salads or soups, the question remains; Is soy sauce keto-friendly?
On the keto diet, restricting your carb intake is paramount. As a result, you’ll need to keep more of an eye on the composition of foods in your diet. In this article, we’ll discuss the carb content of soy sauce, whether it is keto and how to integrate it into your diet.
Table of contents
What is soy sauce?
Soy sauce is a condiment originating from China, but now widely used across the globe. Commonly used in Asian dishes, soy sauce is known for its rich, salty flavour and is traditionally produced from fermented soybeans.
The process of creating soy sauce can vary between different locations (and on the specific type of soy sauce), but generally follows a similar process.
In order to make soy sauce, cooked soy beans are mixed with wheat grains. The combination results in a thick paste that is subsequently fermented, in order to produce the rich umami flavour[1].
To ferment the soybean mixture, the fungi Aspergillus oryzae or Aspergillus sojae are added to the mixture. These fungi are responsible for the fermentation process. In some soy sauces, this mixture is subsequently added to a salty brine solution, which slightly changes the flavour and consistency[1].
Soy sauce produced in different regions has subtle differences in taste, often due to the ratio of soybeans to wheat grains. So, the main thing to know is that soy sauce is produced from fermented soybeans and wheat grains. Yum!
Different types of soy sauce
As I touched on earlier, soy sauce comes in many different varieties. A large part of this variation comes from slightly different cultural influences. As a result, you’ll often see slight differences, for instance, in soy sauce from Japan or from Korea[2].
But with all these slight variations, what do you actually need to know from a practical perspective?
According to MasterClass, there are 4 main categories of soy sauce. Please note that there are different classification systems and various sub-categories of soy sauces, which we will not delve into in this article. The focus of this article will be the 3 most commonly used soy sauces, light, dark and tamari.
If you would like to explore these classification systems in more detail, check out this article on the Chemical and Sensory Characteristics of Soy Sauce.
Light soy sauce
Light soy sauce normally refers to a Chinese-style soy sauce, which is a bit lighter in flavour and has a high degree of saltiness. In is produced in 2 stages, with an initial soybean and wheat fermentation stage, followed by fermentation in brine. This results in a soy sauce that slight ‘thinner’ and does not have the strong umami flavour of some others.
In addition, light soy is normally produced from a higher ratio of wheat grains to soybeans. This means light soy sauces tend to be saltier than darker variations and are commonly used as dipping sauces.
Dark soy sauce
Dark soy sauce is produced from an approximately equal ratio of wheat grains to soy beans. This produces the characteristic dark colour. The darker soy sauces typically undergo a longer ageing process, resulting in a slightly more viscous final product. Unlike light soy sauce, the dark variations tend to be used more in slow cooking applications.
Tamari
Tamari is a type of Japanese soy sauce that is incredibly dark and rich in its taste. The incredible rich taste and viscous consistency are the result of fermenting with almost no wheat.
That’s right, tamari is produced through a slow fermentation process that almost exclusively relies on soybeans. The wheat-free nature of tamari means it is more suitable for those with a gluten-intolerance.
How many carbs in soy sauce?
Now that we’ve covered the different types of soy sauce, let’s get down to the nitty gritty. How many carbs does soya sauce have? The answer is, it varies.
According to the USDA FoodData Central database, soy sauces contain around 1g of carbohydrate per 15g serving (this translates to roughly 15ml). However, soy sauce that is commercially available often has added sugar or other ingredients, increasing the carbohydrate content[3][4].
Is soy sauce keto?
Yes, soy sauce is keto-friendly. With around 1g of carbohydrate per serving, soy sauce can safely be used as a condiment on the keto diet. At this carb content, you can use soya sauce quite freely as a condiment.
You can also use soy sauce quite freely in cooking, for example, stir fries and soups. Just be mindful that soy sauce has high amounts of salt, so ensure you don’t over do it.
As mentioned, many commercially available soy sauces are quite high in sugar, due to added ingredients. As a result, ensure you read the nutritional information before making any purchases. Overall however, soy sauce is keto-friendly and can be used as a condiment or in cooking on the keto diet.
Potential health benefits
May improve gut health
Soy sauce has been shown to improve gut health by promoting digestion. This is achieved by increasing the secretion of gastric juice. By enhancing gastric juice secretion, soy sauce leads to appropriate and timely digestion, which may prevent indigestion and other GI-related conditions[5].
Has antioxidant activity
Soy sauce is rich in antioxidants which helps to prevent damage caused by oxygen free radicals. In fact, a study by the National University of Singapore found that dark soy sauce has antioxidant activity 150 times that of vitamins E and C; And 10 times that of wine[6][7].
While light soy sauce still has some antioxidant activity, dark soy has been shown to have significantly more. More importantly, this antioxidant activity could potentially reduce oxidative damage in conditions such as cardiovascular disease[7].
Has antimicrobial activity
Given its high salt content, soy sauce is very good at preventing microbial growth. Studies have shown that soy sauce is able to kill numerous pathogens, including Escherichia coli, Shigella flexneri, Salmonella typhi, Salmonella paratyphi A, Salmonella enteritidis and Vibrio cholera. As a result, soy sauce is sometimes used as a preservative in raw fish and vegetables[5].
May have anti-inflammatory properties
Fermented soy sauce contains compounds called shoyuflavones (shoyu being a type of soy sauce), which are a type of isoflavone derivatives. These shoyuflavones have been shown to potentially mediate inflammation, as they inhibit histamine production[8].
Histamine is a well-known mediator of inflammation, so by reducing its production, soy sauce may alleviate the inflammatory process[8].
What types of soy sauce should you avoid on keto?
Reduced-salt soy sauce
While soy sauce is generally keto-friendly, there are certain types that you should avoid (or at least pay special attention to). This includes reduced salt soy sauce.
Excessive intake of salt is detrimental to your health and can result in hypertension and cardiovascular disease. As a result, reduced or low sodium soy sauce may seem like a good idea[9].
However, many low salt varieties of soy sauce end up adding ingredients to make up for the loss of salt. This often includes sugar or syrups, resulting in a soy sauce that is much higher in carbs.
Flavoured soy sauce
Other soy sauces to be more cautious with include flavoured sauces. In order to add these ‘flavours,’ manufacturers often add syrups and sugar. Both bad ideas if you’re on the keto diet. Some soy sauces will have fairly obvious labelling, such as ‘sweet soy sauce.’ For others however, it can be much more subtle.
Look out for these types of soy sauces and as always, read the nutritional information!
How to include soy sauce into your keto diet?
Soy sauce is a wonderful sauce with beautiful umami flavour. As a result, it has a broad range of applications on the keto diet.
Dipping sauce
Rice-based sushi is off the table on the keto diet, but doesn’t mean you can’t eat fish. Sashimi, finely sliced portions of raw fish including salmon and tuna, is often dipped into soy sauce. But you don’t have to limit yourself to just fish. Experiment with a range of low carb vegetables and see what combinations work for you.
Sauce for stir fries and soup
When I first started the keto diet, one of my favourite dishes was almond chicken with stir fried vegetables. This is a great dish which tastes amazing with a topping of soy sauce. Similar stir fry dishes can be topped with soy sauce to add some extra flavour, as can a variety of different soups.
Marinades
Another great way to use soy sauce is as a marinade for meat and fish. Coating meat or fish in soy sauce, and allowing it to sit in the fridge overnight, adds to the richness of the flavour. Great options are soy-marinated chicken thighs or salmon.
You can also try lightly coating vegetables in soy sauce, before oven roasting to perfection. The extra saltiness will completely transform the flavour.
What are the alternatives?
If soy sauce just doesn’t quite do it for you or you’re looking for a change, why not try coconut aminos?
Coconut aminos are made from the sap of the coconut palm, which is fermented to create the aminos. The taste is similar to soy sauce, but tends to be slightly sweeter and has less salt than traditional soy sauce.
If you’re gluten-intolerant, this is a particularly good substitute as it is wheat-free!
Conclusion
Overall, soy sauce is a keto-friendly condiment that can be consumed on a low carbohydrate diet. The fermented sauce also comes with a range of health benefits, which is an added bonus to the delicious flavour. However, ensure you pay attention to the nutritional information, as many store-bought varieties contain added sugars or syrups.
