Expert Q&A: Seasonal eating for longevity with Dr. John Douillard

The following interview is a transcript excerpt from The Heallist Podcast episode. Listen to the full audio version below and subscribe to get notified of new episodes.

In this episode of the Heallist Podcast, we explore the intersection of ancient wisdom and modern science with LifeSpa founder Dr. John Douillard, as he shares his perspective on how seasonal eating, breathing practices, and digestive health may influence vitality and longevity. Drawing from both Ayurvedic principles and emerging research, the conversation examines how our bodies interact with natural rhythms and what can happen when those rhythms become disrupted.

Through practical examples, Dr. Douillard discusses the relationship between seasonal foods and the gut microbiome, the role of breathing in supporting lymphatic and immune function, and why food preparation methods have long been emphasized in traditional health systems. We also explore how modern diets, highly processed foods, and reduced exposure to natural environments may affect gut resilience, microbial diversity, and overall well-being. Listeners will gain insight into simple ways of thinking about health through the lens of digestion, nature, and daily habits.

John Douillard: Perfect. Thanks for having me.

John Douillard: Well, I think you're absolutely right. When you have something, a practice, lifestyle, diet, behavior, that's been around for thousands of years, that's something we should look at, study, and evaluate. Today, in our modern science world, science can prove whatever it wants. Coffee is good, coffee's bad, wheat's good, wheat's bad, you name it. There's going to be studies on both sides of the aisle, and nobody really knows what to believe. A lot of influencers are trying to figure it out, and that's beautiful. But those recommendations keep changing. One minute they're saying you should never eat broccoli, and then all of a sudden vegetables are back.

A traditional system of medicine thousands of years old, backed up by modern science, is a really great place to start, because after thousands of years, this stuff doesn't change. We keep bouncing around, chasing the symptomatic relief the previous diet left us craving. The Atkins diet, high protein, gave people kidney issues and cravings for carbohydrates. Then Pritikin came along, the next best-selling diet, saying you could get all the same benefits eating 80% carbohydrates, giving people permission to eat what the last diet restricted.

What's really neat about Ayurveda is that if it didn't work after 100 or 200 years, they would have stopped doing it. So what I do at LifeSpa is I write articles about the ancient medical practices, and then I find science to prove them. If there's no science, I don't write about it. So when

The Three Harvests Of Eating

John Douillard: You have both of them, I feel like that's a really great safe place to start. One of the things they said historically was that we should eat with the seasons. Every human on the planet historically had to eat with the seasons because we didn't have refrigerators. What we now know is that the microbes in the soil are dramatically changing from one season to the next, and hunter-gatherer gut bacteria would change the same way. Ours doesn't. In the springtime, when you're getting a lot of fiber from vegetables and roots, you have more acidobacteria, which help you get energy from fiber. At the end of summer, when there's more starch coming out of the ground, we have more of the bacteria that help digest starch. We actually have an enzyme for starch called amylase, which we started to make as humans about two million years ago, probably because we were eating grains and barley off the grasslands in Africa. They did find gluten in the teeth of ancient humans two and a half million years ago, according to studies from the University of Texas.

The fuel supply changes historically in nature: a high carbohydrate diet at the end of summer and fall, a very low carbohydrate diet in spring, when there's no pasta or pizza coming out of the ground. It's a time of year when you're naturally calorie restricted, which is why religions do their fasting then, forcing you into a fat-burning state that resets fat metabolism and helps you detoxify. In winter, we shift to a higher protein, higher fat diet, think of squirrels eating nuts and seeds. The high protein, low-carb, and high-carb diets all exist in nature, just on an annual cycle, since it takes a whole season for nature to produce a nut, a grain, or a fruit.

I wrote a book called The Three Season Diet, because there are three harvests in nature, not four seasons: a spring harvest, low-carb, a summer harvest, high carbohydrate, and a fall harvest for winter eating, carried as best you can into winter, a dormant season of higher protein and fat. Every traditional culture knew that hunting all summer with nothing left for winter meant starvation, so cultures built in periods of scarcity and restricted hunting. Most figured that out; some, like Easter Island, didn't. I put together free winter, spring, and summer grocery lists on my website to make this easy.

A Stanford University study measured the microbiome of thousand-year-old mummies from New Mexico and Arizona and found such a massive diversity gap compared to modern humans that it was concluded to be an extinction event. It's not just about eating a probiotic, it's getting the right bugs in the right season, because the bugs carry circadian rhythms and intelligence: winter bugs boost immunity, spring bugs decongest, summer bugs dissipate heat. Plants carry bacterial endophytes synergistic with their own microbiome, just like ours is unique to us, and taking that away destroys the intelligence of both the plant and the person eating it. Eating seasonally, organic where you can, gently inoculates you.

All you really need to do is take the grocery list for the season you're in, circle the foods you like, and give yourself permission to eat more of them. You don't eat wheat every day of the year, for example. Because our digestive system has become so weak, we've bubble wrapped our diet, cutting out wheat, then dairy, nuts, seeds, beans, rice, legumes, nitrates, oxalates, goitrogens, and lectins. Those harder to digest foods create hormesis, a little irritation that builds gut immunity, which is 80% of your immune response. Bubble wrap the diet and you lose that immunity: 74% of the American population now has some digestive disturbance affecting gut immunity, part of why we did lousy in COVID. We have to go upstream and troubleshoot the digestive issue, instead of just avoiding foods or taking enzymes to digest for you.

A study comparing wheat eaters to people who were gluten-free but didn't have to be found the wheat eaters had four times less mercury and heavy metals in their blood, more killer T cells, and more good bugs than bad, compared to the needlessly gluten-free group. Bubble wrap your diet and you end up weaker. Eating seasonally means the body gets ready for these changes: more digestive strength in winter for heavier foods, weaker digestion in summer since food is essentially cooked on the vine for you, and fermented, warming foods in winter to keep the furnace going. This is Nobel Prize-winning science: when biological clocks are out of sync with nature's rhythms, that's a dangerous road, and with all the

Fiber And Bile As Daily Detox

John 17:25: Blue light and everything we have, it only makes it worse.

John Douillard: Our intestinal tract is full of microbes, little bugs you can't see. Thousands of years ago, before microscopes existed, traditional systems already talked about invisible bacteria, good ones and bad ones, and said the key to balance is don't kill the bad ones, tend the ecology of the gut. That ecology is supported by seasonal fiber. Grains harvested at the end of summer are high in soluble fiber, slimy, like chia, flax, or oatmeal, and that fiber heals the gut lining and binds to bile, carrying it to the toilet. Bile is your Pac-Man, gobbling up toxins in the liver and cleaning the villi of the intestinal tract. Without enough fiber, up to 93% of that bile, toxins included, gets reabsorbed back into the liver, and the cycle starts over. Bile can get reused up to 17 times before it's finally discarded.

Hunter-gatherers had about 200 grams of fiber a day, per Harvard professor Daniel Lieberman's research in The Story of the Human Body. Try eating just 50 grams in a day and you'll see how hard that is. Soluble fiber comes in the fall harvest, nature's antidote to dry, constipating winter months, and feeds the good bugs. In summer you get insoluble fiber, like celery, which scrubs the intestinal tract and speeds transit time.

Processed foods and pesticides, and herbs sterilized in alcohol until no living microbiome remains, strip away that intelligence. In Ayurveda we use herbs with their naturally occurring microbiome intact, because that's what helps the body restore function. Sterilize it and take away the bugs, and it acts more like a drug, one the body becomes dependent on, needing higher doses over time. Historically, doctors were only paid if their patients stayed healthy, so they were motivated to keep people well. Now we're motivated to keep people sick, and that's sad.

Food Intolerances And Gut Immunity

John Douillard: I started practice in 1984, and these problems didn't exist. Everybody ate rice and beans without issue. Now people can't digest beans, a global staple, because of the lectins on them. I wrote about the science behind lectins, those irritants create gut immunity, the hormesis that makes you adapt and grow stronger. It's easier to blame the food than to figure out what's actually broken in digestion.

A study showed that when protein and fat aren't fully broken down, those molecules are too big to enter the bloodstream and instead get taken up into the collecting ducts of the lymphatic system, which lines the intestinal tract and accounts for 80% of your immune response there. If that lymph gets congested, you get extra weight around the belly and hips, swollen ankles, tight rings, because the lymph can't take the trash out, deliver the immune system, or deliver the fatty acids that give you energy and feed your skin and hormones. So when a doctor says you're low on hormones and offers bioidentical hormones, the first step might be checking whether your lymphatic system is even delivering those fatty acids in the first place.

That lymphatic system, in Ayurveda, is the first system evaluated for longevity. The first studies on long haul COVID were linked to congestion of the brain's lymphatic system, only discovered by Western science about 15 years ago at the University of Virginia, though Ayurveda described it, and gave therapies to clean it out, thousands of years ago. The diaphragm is the pump of your lymphatic system for your brain, pumping the cerebral spinal fluid. When you have COVID, you can't breathe well, so you can't pump that fluid, which likely means inflammation you can't clear, and a compromised immune response.

Studies show that when you strengthen your diaphragm, it can reverse heartburn, GERD, reflux, and indigestion, fifteen studies show that, yet you're never given a breathing technique for heartburn at the doctor's office. A recent study on elite athletes showed 91% didn't have a diaphragm relaxing and contracting fully. A weak diaphragm means congested lymph, water retention, ankle swelling, joint pain, skin breakouts, breast tenderness and swelling around your cycle. You get brain fog when you eat wheat, that's the protein, the gluten, that didn't get broken down.

Lymph Congestion And Brain Fog

John Douillard: It gets taken up into the collecting ducts of your lymph, goes into the brain lymph, and now you have brain fog, and you blame it on the wheat. It's not the wheat, it's the inability to break it down, along with the glyphosate and processed nature of it. I wrote a book called Eat Wheat pushing back on this, the research shows wheat actually reduces your risk of Alzheimer's. I debated the author of the book that made everybody stop eating wheat, my mother's pretty sure I won. It's not the grain we've eaten for millions of years, it's the broken digestion letting more undigested protein into the lymph.

Those three things, taking the trash out, brain fog, and the immune system, that's the longevity ticket, they wrote about that 2,500 years ago. There's volumes of research on the lymphatic system in medical journals, but none of it's in medical practice. What I try to bring to the table is the research, the ancient wisdom, and the foods and herbs to get that system back online, so you can reboot your digestive strength and stop clogging up your lymph.

Diaphragm Breathing As A Health Tool

John Douillard: We live in a stressful environment, and every time you get stressed, you breathe a little shallower, and that becomes normal. Repeat that enough and your diaphragm weakens. The most important thing for longevity is turning the lymphatic pump and cerebrospinal fluid pump back on, what Western medicine calls maximum inspiratory breathing, done slowly, so it's calming rather than a fight or flight breath.

Breathe in through your nose, belly first like a Buddha, then chest, then upper chest, taking little sips of air until you feel a pull under the rib cage. Exhale long and slow, contracting the abdomen to squeeze all the air out. This breathing reverses heartburn, GERD, reflux, and indigestion, lowers blood pressure as fast as medication, and cleans out the brain's lymphatic system. Take it further by raising your arms as you breathe, which helps break up rigidity in the rib cage. Five minutes a day, right in front of your computer, is enough to get the diaphragm working again.

Five Spices That Boost Digestion

John 38:05 For digestion, there are five spices to know: ginger, cumin, coriander, fennel, and cardamom, already in most spice cabinets. Sprinkle them on food while cooking or eating. Studies show they turn on stomach acid, bile flow, and pancreatic enzymes, so hard-to-digest food nourishes you instead of ending up as congestion in the lymphatic system.

These same spices protect against heterocyclic amines, the cancer-causing compounds from charring meat, and acrylamides, from browning starches like toast. Cooking also creates reactive oxygen species, free radicals that damage food, and spices mitigate that too. They're not just for taste, they've been used worldwide because they keep digestion strong, especially against today's processed foods and digestion-suppressing stress.

John Douillard: My website is LifeSpa.com, where you can get the seasonal grocery lists for free. There's a banner on the homepage that says "new here, start here." There's also a digestive health quiz and a lymphatic quiz, to find out what's broken and how to fix it naturally with herbs, lifestyle, and diet. We have over 1,500 free articles on the site, all ancient wisdom backed by modern science, that's our business model. We have an herbal company that formulates and sells the herbs, that's what pays the bills, but all the knowledge on the site is free, it's a library.

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