The link between blood sugar, digestion, and immunity has been described by Traditional Chinese Medicine physicians since ancient times.
Now we are seeing that link play out on a global scale. If there was ever a good time to start eating better, now would be it. Common sense tells us that in the truest sense of the phrase, you really "are what you eat". We know that what we feed our body becomes our body, and our immune system is no exception to that rule. Give an army the best equipment and they will be more effective against their enemy. Give the immune system the best food and it will be more effective as well. However, understanding what to eat can be a confusing topic, and the slew of conflicting health information around nutrition could understandably lead some to just give up. Instead of only looking to the constantly shifting modern debate around nutrition, let's explore the hard-earned wisdom and time-tested knowledge accumulated over thousands of years by Traditional Chinese Medicine (TCM) doctors. In this article we will explore how TCM, and science now too, draws a connection between digestive health, blood sugar regulation, and immunity.
Carbohydrates: Friend or Foe?
Let's first talk about digestion. In TCM the Earth Phase is the element of digestion, and represents the quality of energy that moves through the spleen, stomach, and pancreas. When our Earth phase of Qi is strong, it holds our other energies in balance and brings our blood and energy to our center - helping us feel more centered and balanced, and focusing our resources on digestion. In TCM the ultimate goal of all healing is balance, so the Earth phase and digestion are considered of central importance. We see this now with modern holistic medicine, which recognizes that most of your health starts and ends with what is on your fork. You truly are what you eat, after all. But in TCM, you are also what you digest. I have had many clients with long term health issues tell me that they tried every diet in the world and didn't find any long term healing until they found Qigong. It didn't matter what they ate, because their chronic stress levels were preventing their bodies from processing that food effectively. Once their minds settled and their Qi returned to their center, they were able to digest properly again and began to heal. Asides from Qigong, how do we become more centered and improve our digestion? With sweets! Sort of. Not really sweets, but sweetness. Mild sweetness. Almost not sweet at all sweetness. Like white rice. Or yams. Starch, really.
See, each elemental phase in TCM has a flavor that strengthens it. But an extreme form of that flavor can also weaken it.
Carbs from a Chinese Medicine Perspective
Mildly-sweet starchy foods like potatoes, millet, corn, etc strengthen the spleen/stomach/pancreas Qi. Excessively sweet foods will tend to weaken it by creating "dampness", a condition in TCM in which the Chi is restricted by a metaphorical "dampening", leading to weak energy and stagnation.
What is excessively sweet will vary from person to person - depending on genetics, exercises levels, and health status - but in general, eating too much fruit and especially sugar (even natural sweeteners like maple syrup) will weaken the Earth Phase of Qi (digestion).
Physiologically, this makes sense since the pancreas is responsible for both the maintenance of blood sugar/insulin as well as the secretion of digestive enzymes.
Theoretically the TCM metaphoric/energetic framework implies you can stress your pancreas by causing insulin spikes with sugary foods. Then the pancreas will be weakened in its ability to manage digestive functions. - A brilliant poetic deduction translating to biochemistry from the ancient Taoists!
So perhaps the best way to think about the Chinese view of digestive health is that it is intimately tied to balancing blood sugar. Favoring starches over sugars is generally understood to maintain stable blood sugar, and stable blood sugar is known to help keep your mood balanced and your cognition clear.
The only thing that might be counter-intuitive to the western understanding is that generally the Chinese view prefers white/refined grains over whole grains. This is because the husk of the grain is the most difficult part to digest and can be irritating to the gut, while the starchy inside of the grain (the white part) is like baby food for the gut and assimilates easily.
In order to make up for the lost fiber, most Chinese dishes mix lots of cooked vegetables in with the starches. Vegetable fiber is generally less irritating than whole grain fiber, and comes with more nutrients as well (Cooking vegetables is another common principle in Chinese dietetics, as the cellulose in raw vegetables generally "dampens" the digestive Qi).
Consuming vegetables and protein (nuts, seeds, or meats) along with your starch will slow its conversion to blood sugar and give you that slow burn of energy that helps you feel stable and centered. This lowered stress allows the pancreas to focus on digestion instead of chasing down erratic sugar levels with insulin.
But how the heck does improving digestion and balancing blood sugar benefit your immune system?
In TCM, the energy derived from food is called "Gu Qi" (yes, pronounced just like the brand), which translates to "Grain Energy". Gu Qi accounts for 70% of your overall Qi. The Earth organs (stomach, spleen, pancreas) are said to extract Gu Qi from food and send it to the rest of the body to form the "Ying Qi" - the nourishing energy for inside the body - and the "Wei Qi" - the protective energy for the immune system. Thus the first line of defense in TCM is to strengthen digestion. But it isn't just TCM where we see this connection. It has become clear that one of the highest risks groups for COVID-19 complications is people with Diabetes. As the International Diabetes Federation states: "Innate immunity, the first line of defense against SARS-CoV-2, is inevitably compromised in patients with uncontrolled DM [Diabetes Mellitus] thereby allowing unhindered proliferation of the pathogen within the host."
Cleary poor blood sugar regulation weakens immunity. But as this study shows, it isn't even only in people with full blown diabetes: "Even short-term hyperglycemia has been shown to transiently stun the innate immune system." https://www.amjmedsci.org/article/S0002-9629(15)00027-0/fulltext Keeping our blood sugar stable not only stabilizes our mind and emotions, but may actually help keep our immune system running smoothly and help us stay resilient. That's empowering stuff! To summarize, maintaining stable blood sugar levels, even for non-diabetics, may help improve digestion, lower stress, improve cognition, and even boost immunity. In our modern world with sugar added to so many things, it may be helpful to make an effort to choose more stable sources of carbohydrates like rice, yams, and potatoes, as TCM has been suggesting for centuries.
SARS-CoV-2 may be a novel virus, but ancient wisdom can still play a role in facing this new challenge. At the very least, it helps put our mind at ease when there are small things we can do personally to lower our risk of complications, besides just focusing on not getting sick!