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What a Vegan Diet Actually Does to Your Body?

  • Writer: Emanuele Bortolotto
    Emanuele Bortolotto
  • Jul 23
  • 7 min read

Updated: Sep 8





I’ve always been fascinated by the human body’s resilience. It’s like an incredibly adaptable, slightly squishy, and perpetually surprising machine. It can run on an astonishing variety of fuels, from whale blubber to wild berries to weirdly compelling processed cheese snacks. It complains, it creaks, it breaks down, but for the most part, it just keeps going. As an investigator of how and why we do the things we do, this adaptability made me wonder: what happens when you radically change its fuel source?

It's a crisp Wednesday afternoon here in Helsinki, a city filled with practical, well-maintained cars that run on precisely the right kind of fuel. It’s a culture of efficiency and good engineering. This got me thinking about our own internal engineering. What is the premium fuel for the human machine? This line of questioning inevitably leads to one of the biggest dietary shifts a person can make. So today, I’m launching a full-scale investigation to answer the big question: what does veganism do to your body?


The Two Manuals: A Crucial Distinction


Before we can even begin, I have to make a critically important distinction. The answer to our question depends entirely on which version of the "vegan manual" you decide to follow. The word "vegan" simply means a diet devoid of animal products. It is not, I repeat, not a synonym for "healthy."

Imagine you’ve just acquired a high-performance vehicle.


  • Manual #1 (The Whole-Food, Plant-Based Diet): This manual instructs you to fill the tank with premium, clean-burning, high-octane fuel. This is a diet built on a foundation of fruits, vegetables, whole grains, legumes, nuts, and seeds.

  • Manual #2 (The Junk-Food Vegan Diet): This manual tells you that as long as the fuel doesn't come from a specific source, it's fine. So, you fill the tank with sugary soda, melted gummy bears, and crisps. 🍬

The vehicle is the same. The results will be catastrophically different. For the remainder of this investigation, when I talk about the effects of a "vegan diet," I am referring to the first manual: a well-planned, whole-food, plant-based diet. Because honestly, we don't need a 3000-word article to know that a diet of soda and crisps is bad for you.


The Engine Room: Your Heart on Plants ❤️


The area where I found the most dramatic and undisputed scientific evidence is cardiovascular health. The effect of a whole-food vegan diet on the heart and circulatory system is nothing short of profound. It’s like taking your body’s engine in for a complete overhaul and tune-up.


The Cholesterol Question


For decades, we’ve known about the link between high blood cholesterol, particularly LDL (low-density lipoprotein, the "bad" kind), and heart disease. My investigation showed me two ways a vegan diet tackles this. First, dietary cholesterol is found only in animal products. Plants contain zero cholesterol. By cutting out animal products, you eliminate 100% of dietary cholesterol from your intake.

Second, and more importantly, is the effect on saturated fat. While some plant foods are high in saturated fat (I’m looking at you, coconut oil), a diet based on whole plants is naturally very low in it. High intake of saturated fat prompts your own liver to produce more LDL cholesterol. By dramatically reducing this, you allow your body’s cholesterol levels to fall. The soluble fiber found in oats, beans, apples, and flaxseed also plays a heroic role, actively binding to cholesterol in your digestive system and escorting it out of the body before it can clog up your arteries.


The Blood Pressure Benefit


I've written about this before, but it's a cornerstone of the conversation. A whole-food vegan diet is a multi-pronged strategy for lowering blood pressure. It is naturally very high in potassium (from fruits, vegetables, potatoes) and low in sodium, a mineral ratio that helps your body release excess fluid. Furthermore, leafy greens and beetroots are packed with dietary nitrates, which your body converts into nitric oxide. Nitric oxide is a vasodilator, meaning it relaxes and widens your blood vessels, allowing blood to flow with less pressure. It's like turning a narrow country lane into a four-lane motorway.

It’s a fascinating paradox I discovered in my research. The traditional food culture of Italy, which I love, is famous for things like prosciutto and parmesan, both very high in sodium. Yet the foundational “Mediterranean diet,” which is lauded for its heart benefits, is actually incredibly plant-heavy. The science shows it's the olive oil, the abundance of vegetables, the tomatoes, and the legumes—not the cured meats—that provide the powerful cardiovascular benefits.


The Plumbing & The Garden: Your Gut on Fiber 🌿


The effect of switching to a high-fiber, plant-based diet on your digestive system is, to put it mildly, dramatic. For many, it’s a two-act play.

Act I: The Chaos. When you dramatically increase your fiber intake, the trillions of bacteria living in your large intestine (your gut microbiome) are suddenly presented with a feast they may not be used to. The result can be a temporary but significant increase in gas and bloating. This is the "adjustment period," where your internal ecosystem is rapidly remodeling itself.

Act II: The Golden Age. Once your microbiome adapts, the magic begins. Fiber is a prebiotic, which means it’s the perfect food for your beneficial gut bacteria. A diverse intake of plant fibers leads to a diverse and thriving gut microbiome. These happy bacteria ferment the fiber and produce incredible compounds called short-chain fatty acids (SCFAs), like butyrate. Butyrate is the preferred fuel source for the cells lining your colon, and it has powerful anti-inflammatory effects that extend throughout the entire body. A healthy gut is linked to a better immune system, improved mood, and lower inflammation.


The Long Game: Cancer Risk and Longevity


This is a more complex and controversial area, but the long-term data is compelling.


Reduced Cancer Risk


The World Health Organization (WHO) has classified processed meat (like bacon and salami) as a Group 1 carcinogen, meaning there is strong evidence that it causes cancer, specifically colorectal cancer. It's in the same category as tobacco smoking and asbestos. Red meat is classified as a Group 2A carcinogen, meaning it "probably" causes cancer.

A whole-food vegan diet eliminates these risks. But it also adds powerful protective elements. The same fiber that fuels your gut helps to speed transit time through your colon, reducing the exposure of your colon walls to potential carcinogens. Furthermore, plants are packed with thousands of phytonutrients and antioxidants—the compounds that give them their vibrant colors. These substances have been shown in countless studies to protect cells from the kind of damage that can lead to cancer.


Questions from the Internet: "Do vegans live longer?"


This is the ultimate question, isn't it? My investigation led me to the Adventist Health Studies, a series of massive, long-term studies on a population of Seventh-day Adventists, many of whom are vegetarian or vegan. The results have consistently shown that those on plant-based diets have lower rates of chronic disease and tend to live significantly longer than the general population.

Now, we must be intellectually honest. Is it just the diet? People in this community also tend to not smoke, drink very little alcohol, and exercise regularly. It's very difficult to perfectly isolate the diet from these other healthy lifestyle factors. However, even when researchers control for these factors, a significant advantage for the plant-eaters remains. The most reasonable conclusion is that a vegan diet is a massive piece of a larger, healthy lifestyle puzzle that can lead to a longer, healthier life.


Questions from the Internet



Questions from the Internet: "What happens to your body when you first go vegan?"


This is what I like to call the "transition period," and it can be a wild ride. For the first few weeks, many people report a surge in energy and mental clarity, possibly due to cutting out heavy, processed foods. Digestion can be a bit... unpredictable, as your gut microbiome adjusts to the fiber tsunami. You might also experience cravings for your old favorite foods. Some people report a kind of "detox" effect with mild headaches as their body adjusts. Over time, these effects usually level out, leading to a new, stable normal.


Questions from the Internet: "What about bone health? Isn't osteoporosis a risk?"


This is a very important and nuanced question. My research shows that it is a potential risk, but only on a poorly planned diet. Some studies have found that vegans can have slightly lower bone mineral density than omnivores. However, this doesn't always translate to a higher fracture risk. The key is ensuring adequate intake of the bone-building dream team: Calcium and Vitamin D. If a vegan is diligent about consuming calcium-fortified plant milks, calcium-set tofu, and leafy greens, and they have adequate Vitamin D levels (likely from a supplement), their risk of fracture appears to be no different from anyone else. The risk comes from a lazy diet that ignores these crucial nutrients.



The Conclusion: A Fuel Upgrade


So, after this deep dive into the body's machinery, what does veganism do to your body?

My investigation leads me to a clear conclusion. When you switch your body's fuel source from a standard diet to a well-planned, whole-food vegan diet, you are giving it a major upgrade. You are providing it with a fuel that is richer in fiber, vitamins, and anti-inflammatory phytonutrients, and lower in inflammation-driving saturated fat and cholesterol.

The potential results are profound: a significantly lower risk of heart disease, type 2 diabetes, and certain cancers; a healthier gut microbiome; and a more manageable body weight. This is not a mystical belief; it is a consistent finding in the vast body of nutritional science.

Of course, these benefits are not guaranteed by the "vegan" label alone. They are earned by the conscious choice to build a diet based on the incredible diversity and power of whole plant foods. It’s the ultimate act of preventative maintenance for your own incredible, squishy machine.

Of course, a healthy body is nothing without a healthy mind. For a look at the complex relationship between diet and mental health, you can read my investigation: [Can Veganism Cause Anxiety?].


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