On New Year’s Day, a crowd gathered on the shore of the Puget Sound, anticipatory energy in the air. The sun was shining on my skin, warming my body in preparation for the 47-degree temperatures (both in the water and in the air), and everyone was stripping down to their swimsuits.
This New Year’s tradition, lovingly referred to as the “Polar Plunge,” is an example of cold therapy, which is thought to have benefits for your mitochondria and immune system as well as for increasing longevity.
In Lifespan: Why We Age — and Why We Don’t Have To, David Sinclair notes cold therapy as one way to expose your body to the right level of stress to slow down the aging process. Sinclair’s book hinges on the premise that just enough stress increases longevity by inducing favorable and protective biological processes, such as maintaining the integrity of mitochondrial DNA.
What Do Mitochondria Do?
Mitochondria regulate cellular energy metabolism by producing adenosine triphosphate (ATP) via oxidation-reduction (a chemical reaction involving an exchange of electrons). The nutrition we put in our bodies provides electrons that are channeled into what’s known as the electron transport chain. Protons are pumped into the intermembrane space (mitochondria have two cell membranes), creating a proton-motive force that provides the energy needed for ATP synthesis via mitochondrial oxidative phosphorylation, only this process isn’t perfectly coupled to ATP synthesis, partly because uncoupling proteins can tell protons to move from the intermembrane space into the mitochondrial matrix. In fact, this is thought to be responsible for 20–30% of our basal metabolic rate!
Why Cold Exposure Works
Uncoupling proteins protect our mitochondria against oxidative damage. Free radicals, also called reactive oxygen species, react easily with other molecules in ways they’re not supposed to, and overproduction of free radicals creates oxidative stress, which leads to DNA damage and throws the body into a state of inflammation.
Cold exposure increases the number of mitochondria in our bodies and activates uncoupling proteins, resulting in improved mitochondrial function and faster metabolism. When we take cold showers, sleep with fewer covers at night, take an ice bath, or run into a near-freezing body of water, we feel good afterwards because our mitochondria are alive and happy.
Another way to experience the benefits of cold is hot/cold therapy, which stimulates blood flow and moves oxygen through our bodies. Warm water moves blood to our limbs, while cold water causes our blood vessels to constrict and direct blood flow to our hearts, to stay warm.
To try this the next time you take a shower, alternate showering in warm water for 3 minutes and then turning the water as cold as you can stand for 30 seconds. Some hot springs also have cold pools, so you can alternate between warm and icy cold temperatures.
Other Ways to Care for Your Mitochondria
Remember when I said that cold increases the number of mitochondria you have? This mitochondrial biogenesis is stimulated by AMPK (AMP-activated kinase) pathway, which senses how much ATP is in your cells and can actually reprogram your metabolism and support metabolic balance at the whole-body level. Why would your mitochondria reprogram your metabolism? The answer has to do with glucose.
Glucose Balance
Glucose is a simple sugar, the kind our bodies use to create energy in the form of ATP. As Jessie Inchauspé describes in Glucose Revolution: The Life-Changing Power of Balancing Your Blood Sugar, in plants, glucose can be stored as starch (long chains, mostly found in root vegetables), fiber (linked chains, which makes them indigestible, found in all plants and especially in trunks, branches, and leaves, if we’re talking plant anatomy), fructose (found in fruit), or sucrose (glucose + fructose, smaller than lining up the two molecules side by side, which helps plants to store energy).
There are many kinds of carbohydrates, and other macronutrients can be turned into glucose as well (metabolic flexibility is a measure of how well your body is able to burn fat instead of glucose and is an indicator of healthy metabolism). Regulating your blood glucose levels is important because glucose spikes deliver more glucose to our cells than they need. According to the Allostatic Load Model, when this happens, mitochondria can’t process all of that glucose at once, and free radicals are released, damaging our mitochondrial DNA and leading to oxidative stress. Then, because our damaged mitochondria can’t convert glucose to energy efficiently, our cells starve, and we feel tired.
To flatten your glucose curves, Jessie outlines 10 “hacks," which I'll list and then explain in my own words:
1. Eat Foods in the Right Order
This trick works because of the plant anatomy we talked about above. Eat vegetables (fiber) first, protein and fats second, and grains and other starches last. The fiber reduces the action of alpha-amylase, an enzyme that breaks down starch into glucose; slows the digestion process, balancing our blood sugar; and makes it harder for our small intestine to absorb glucose. Absorbing less glucose doesn’t make us tired; in fact, the opposite is true — if we’re following no.1, we have sustained energy throughout the day and increased metabolic flexibility.
2. Add a Green Starter to All Your Meals
Starting with a salad is a simple way to remember to eat fiber first. It’s an opportunity to be creative, too — almost any vegetable(s) will do!
3. Stop Counting Calories A glucose-flattening diet allows you to eat more calories and lose more weight than you’d be able to with more dramatic glucose curves.
4. Flatten Your Breakfast Curve
Given that breakfast is the first thing you put in your body in a day, there is more potential for a spike! Be kind to your body by swapping sweet for savory breakfasts to dramatically reduce the spike.
5. Have Any Type of Sugar You Like—They’re All the Same
Even better, opt for sweet spices like cinnamon, 100% chocolate (cacao nibs or bars), berries, and other sweet-tasting foods that are low in sugar.
6. Pick Dessert over a Sweet Snack
The reason for this is the same as in no.1, in addition to the fact that snacking increases the time our bodies spend in a post-prandial state. The time our bodies are not in a post-prandial state is when they’re able to replace damaged cells with new ones and our insulin levels come down.
7. Reach for Vinegar Before You Eat Any kind of vinegar has been shown to reduce the effect of what you put in your body after. Mixing a simple vinaigrette of olive or avocado oil and white or apple cider vinegar is a simple way to add vinegar and a green starter at the same time.
8. After You Eat, Move When you spend even 10 minutes walking after a meal, you tell your mitochondria to turn those nutrients into glucose to move your muscles, which moves glucose our of our bloodstream. If you’re going to work out, the time to do so for the greatest reduction to glucose and insulin spikes is after a meal, but before a meal works great too. Fasted exercise (i.e., first thing in the morning) creates free radicals, but because exercise improves the body’s ability to fight free radicals, the net effect is positive.
9. If You Have to Snack, Go Savory
A glucose spike is accompanied by a spike in insulin. Insulin’s role is to remove blood glucose. It does this by storing glucose as glycogen (in our liver and muscles) or as fat. Fructose can only be stored as fat because it can’t be turned into glycogen. So, the same number of calories as a sweet food (containing fructose or sucrose) is more likely to lead to weight gain than as a savory food. Fructose also increases glycation, in which glucose molecules attach to other molecules, further contributing to oxidative stress, inflammation, and aging. In fact, David Sinclair notes that we become more insulin-resistant as we age due to a process called ex-differentiation, in which our cells lose their identity due to DNA damage. We also lose glucose transporters.
10. Put Some Clothes on Your Carbs Adding protein, fiber, and/or fat decreases the amount of insulin released in response and keeps us feeling full for longer. Ghrelin, the hormone responsible for hunger, bottoms out quickly and then just as quickly rises even higher when we eat a carb on its own. Proteins take longer to make us feel satiated but keep us feeling full the longest. Fats fall somewhere in between.
Hormones Are the Stars
It's worth noting that many hormones play a role in glucose homeostasis, including how our body derives and stores energy. When glucose is no longer freely circulating in our bloodstream, our bodies have two choices: glycogenolysis (turning stored glycogen into glucose, promoted by glucagon; in contrast to glycogenesis, the synthesis of glycogen from glucose, promoted by insulin) or gluconeogenesis (creating glucose from non-carbohydrate sources). Insulin and its opposite, glucagon, regulate these processes.
Other hormones involved in glucose homeostasis include cortisol, epinephrine, amylin, and GLP-1, or glucagon-like peptides, and all of these hormones are produced in different places in the body! For example, ghrelin is made in the stomach; amylin, which slows stomach emptying and inhibits the release of glucagon, is made in the pancreas; and GLP-1, which stimulates insulin secretion and slows stomach emptying, is made in the small intestine.
High-Intensity Interval Training
Vigorous exercise requires a lot of glucose and therefore activates the AMPK pathway. It also activates hypoxia-inducible factors as in the HIF-1α pathway. In the same way that the AMPK pathway senses the level of ATP in a cell, the HIF-1α pathway senses how much oxygen is in a cell. When the cell in a state of hypoxia, or lack of oxygen, mitochondrial respiration (the process by which mitochondria produce ATP) can’t happen, and biogenesis is inhibited through altered gene expression.
A little mitochondrial stress, however, is good: when there is slight hypoxia, as in vigorous exercise, your body manufactures more mitochondria, giving you more energy, and stimulates the formation of blood vessels, to transport oxygen throughout your body. This is one reason that the more you exercise, the less easily fatigued you are.
Naturopathic Approaches
One of the first areas a naturopathic doctor worked on with me when I came to her was energy-stabilizing support. One aspect of naturopathic medicine that I find fascinating from a biochemistry perspective is its focus on giving your body the micronutrients and cofactors the body needs to carry out the natural processes that make us feel good.
I took a supplement called Pure Endurance (Physician’s Standard), which facilitates oxygen and nutrient transfer to cells and muscles (by now, the importance of these processes should make sense!). Specifically, it contained Vitamins B1 and B2, selenium, acetyl L-carnitine, L-carnosine, CoQ10, and lithium.
B-vitamins serve as cofactors or coenzymes required for energy metabolism, and Vitamins B1 and B2 are involved in the tricarboxylic acid cycle. Selenium has a reputation for improving thyroid function, but it also improves mitochondrial function (the thyroid affects mitochondrial biogenesis).
Many more ingredients can improve mitochondrial dysfunction, among them L-carnitine, a transporter in mitochondrial metabolism, and CoQ10, a cofactor in the electron transport chain. Carnosine may prevent glycation. Lithium may increase mitochondrial respiration and prevent the shortening of telomeres, which happens as we age.