by Althea Zanecosky, MS, RD, LDN
Since March 2020, data shows that Google searches for phrases like “can’t taste food” spiked around the world – particularly in areas where COVID-19 hit hardest.
Most people do experience a temporary change in the flavor (and often the smell) of food with a common cold or the flu (influenza). COVID-19 – the disease caused by the SARS-CoV-2 virus – sent researchers to look farther into what affects smell and taste.
The Importance of Taste
One reason that taste and smell sensations are important is that they prepare our bodies for digesting food. Tasting and smelling food trigger our salivary glands and digestive “juices”. Without them, our stomachs wouldn’t be ready for food, and we’d have trouble digesting and making use of the nutrients we get from food.
The senses of taste and smell also provide information about our food. The aroma of a food can sometimes tell us if the food is fresh (especially important for fish, meat and dairy). After even a small taste of some foods, we can often detect “off” flavors that may signal that the food has spoiled. We rely on our senses of taste and smell to warn us away from foods that may be dangerous.
And the ability to taste is so crucial to the act of eating that when we can’t taste our food, we just don’t have the desire to eat as much as we usually do. For some of us this may be desirable, but for others it can lead to impaired immunity, poor nutritional status and the worsening of some health conditions.
Science has established that humans detect five basic taste qualities – sweet, sour, bitter, salty, and savory. Savory is also known as umami, which is the Japanese word for “delicious essence.” Umami is the taste of glutamate, an amino acid found throughout the human body and in protein-containing foods. Glutamate elicits a sensation which is often described as brothy, full-bodied, meaty, and savory. Umami taste has been regarded as an essential component of Japanese cuisine for hundreds of years, and is now used in cooking worldwide.
To picture savory taste, think chicken broth, a ripe tomato, Portobello mushroom, or Parmesan cheese. These savory foods all have high concentrations of glutamate. Glutamate is often added to foods in the form of its monosodium salt, MSG, which breaks down into its component parts, sodium and glutamate, after being ingested. Recent biochemical studies have revealed a separate taste receptor that can detect this amino acid, reinforcing the fact that umami is a separate and distinct taste sensation, which perhaps evolved to ensure adequate consumption of protein.
Not Just on the Tip of Your Tongue
What’s important to know is taste goes beyond the sensory systems in your mouth. Other sensations from food occur via our sense of smell, even though we experience them in the mouth. Volatile organic compounds are released when we chew. These chemicals travel through the back of the throat to reach smell receptors found at the top of the nasal cavity.
Another sensory system involved in food flavor involves temperature nerves that can also be activated by chemicals. This is known as chemesthesis. In the mouth, these sensations include the burn of chili peppers, the cooling of mints, or the tingle of carbonation. Together, these three chemosensory systems – taste, smell and chemesthesis – work to define our perceptual experiences from food.
COVID and Taste
Loss of smell is common with many viruses, including influenza and coronaviruses, and it is usually attributed to nasal inflammation that restricts airflow. In other words – if your nose is blocked, you are not able to smell much. The other two systems – taste and chemesthesis – are not affected, as a blocked nose does not alter our ability to taste sugar as sweet or feel the burn from a chili pepper.
Current science studying COVID suggests that the reason why people may think they are experiencing taste loss is actually because their sense of smell – which has a huge impact on their ability to detect flavor – has been impacted. All the sensations detected on the tongue, including umami, are not thought to be affected by COVID.
A current question is: how well do COVID-19 patients recover their sensory perception loss? Those who lose their sense of smell or taste need not resign themselves to a lifetime of joyless eating. The AAO (American Academy of Otolaryngology) found that the average length of time patients experience those symptoms was seven days, with 85 percent of patients regaining their senses within 10 days.
Because more COVID data is needed, taste scientists are asking for help with their research. If you know anyone who is (or recently has been) coughing and sniffling with COVID, invite them to complete the Global Consortium for Chemosensory Research survey. Here’s the link: https://gcchemosensr.org/surveys/
MSG Can be Helpful
The addition of MSG to foods can be helpful to some people who experience taste and smell losses. Using MSG can reduce the perceived bitterness or acidity of foods, which can be helpful when cooking things like vegetables. Using MSG adds an umami (savory) taste to foods, in effect giving more emphasis to the flavors that are already present in the dish. MSG added to a chicken soup makes the soup taste more like chicken by deepening existing flavors and contributing to a fully-developed flavor profile.
The ability to taste and smell our food is vitally important for our health and well-being. Not only does food nourish the body, it provides nourishment for the soul. It’s because of taste that eating is considered a pleasurable experience – one that we like to repeat several times a day. For some people who may have a diminished sense of taste, using a flavor enhancer such as MSG can help counteract the problem.
- How to Build Depth and Dimension in a Dish
- Umami is Not Just Japanese, It’s Universal
- Tasting the Fifth Taste
- Improving Taste
This article first appeared on the MSGdish blog. It is reprinted with the permission of MSGdish and Althea Zanecosky, the author and consulting dietitian.