There is no greater debate in the nutrition world than what is the best diet for health and human longevity?
We’ve seen trends ebb and flow. In the 80s it was low fat, then Atkins low carb, then vegan (always trendy but really took off in the past couple decades), then Paleo, low carb, keto, carnivore, but always with ‘plant-based is better for the earth and our health’ in the background. I always say it’s no wonder I have a job because everyone is so dang confused about what to eat.
So what is the best diet for human health? Is it a plant-based diet or an animal-based diet, or something in between? Let’s take a look.
Plant-Based vs Animal-Based Diet
I’ve written before about vegetarian vs omnivore diets. You can read the main posts on that here and here. But this post is a little different, because I’m focusing on plant-based (which, as you’ll see does not necessarily mean vegetarian) vs animal-based, which is a carnivore diet, or a carnivore diet that allows very limited fruits and vegetables.
First off, the basics: what is a plant-based diet and what is an animal-based diet?
A plant-based diet focuses primarily on plant foods (duh). Many people assume plant-based means vegetarian or vegan, no meat, but while a plant-based diet emphasizes plant foods, it doesn’t necessarily exclude all animal products. Some variations may include dairy, eggs, fish, and meat. The focus, however, remains on maximizing plant foods for health benefits like reduced risk of chronic disease, improved digestion, and better overall health. A plant-based diet focuses on the following:
- Fruits: all types provide fiber and disease-fighting antioxidants
- Vegetables: A wide variety, including leafy greens, root vegetables, and cruciferous vegetables
- Whole Grains: rice, quinoa, oats, buckwheat, amaranth, wheat products if tolerated
- Legumes: Beans, lentils, and peas are excellent sources of protein, fiber, and essential nutrients.
- Nuts and Seeds: provide healthy fats, a little protein, and various vitamins and minerals.
- Plant-based fats: olive oil and avocado oil mainly, sometimes coconut oil
As mentioned, plant-based diets can be fully vegan, excluding all animal products, or they may include lighter proteins such as fish, eggs, poultry, red meat sparingly, or any combo thereof. Typically with a plant-based diet you’ll see 50 percent or more of your calories coming from plant foods and about 25 percent or less from animal proteins. The Mediterranean diet is probably the most popular plant-based diet that includes anti-inflammatory and omega 3-rich proteins like salmon, sardines with minimal red meat.
Animal-based diets have captured the spotlight lately as many instagram influencers starting touting its ability to reverse chronic illnesses like autoimmune disease and digestive issues like IBD. Carnivore is the most popular animal-based diet, and it typically excludes everything except animal products. Read my post on the carnivore diet here.
Animal-based diet includes the following:
- Meat: Beef, pork, poultry, and lamb are common sources of protein and essential nutrients
- Fish and Seafood: salmon, tuna, roe (fish eggs), and shellfish provide protein and omega-3 fatty acids
- Dairy Products: Milk, cheese, and yogurt can be included but often are not
- Eggs: A versatile protein source rich in vitamins and minerals.
- Animal Fats: butter, ghee, and lard, which can be used for cooking and flavoring.
Often carnivores will supplement with electrolytes and use sea salt liberally.
While some proponents of animal-based diets advocate for excluding all plant foods, others include small amounts of low-carb vegetables or fruits and honey. The diet is high in protein and fats and low in carbohydrates, and it is believed to support weight loss, muscle gain, and overall health. However, it may also raise concerns about nutrient deficiencies and long-term health risks.
Plant-Based vs Animal-Based Diet: Which is Better?
First off, one reason people are so confused about the ideal diet is because there is never a one size fits all approach that can be assigned to the perfect human diet. We are all genetically different, and what works wonderfully for one person could be detrimental to another. Your ideal diet depends on your gender, age, health status, and other factors. I can’t tell you how many times I’ve heard “my neighbor lost 20 pounds doing paleo and I gained weight!” Sure, we have guidelines from studies on longevity and disease prevention, but applying them to individuals depends on a number of factors.
So the issue that really gets under my skin is the echo chamber screaming about how <insert fad diet> changed a person’s life, reversed his or her chronic disease, and so this is the best diet for everyone! What you’re not seeing on these instagram echo chambers are the hundreds of people who tried the diet and felt worse than ever, or even worse, had metabolic changes like elevations in cholesterol and inflammatory markers.
But let’s have a look at which diet is better for human health: animal-based or plant-based?
The first point to make here is that plant-based diets in various forms (vegan, vegetarian, Mediterranean) have been studied for decades and have been proven to benefit health in myriad ways:
- Chronic Disease Reduction: Research shows that plant-based diets are associated with a lower risk of chronic diseases such as heart disease, type 2 diabetes, and certain cancers.
- Weight Management: Plant-based diets are often lower in calories and higher in fiber, which can help with weight loss and weight maintenance. Studies have found that individuals on plant-based diets tend to have lower body mass indexes (BMIs).
- Improved Heart Health: Many studies demonstrate that plant-based diets can improve blood lipid profiles, lower blood pressure, and reduce the risk of heart disease. Diets rich in fruits, vegetables, whole grains, nuts, and legumes contribute to better cardiovascular health.
- Gut Health: A diet high in plant foods promotes a diverse and healthy gut microbiome, which is linked to various aspects of health, including digestion and immunity.
- Diabetes Management: may improve insulin sensitivity and blood sugar levels, making them beneficial for those with diabetes or at risk of developing it.
Increasing plants and therefore fiber in your diet typically yields positive health benefits (in most people, always exceptions to this). This is also widely established in nutrition and medical research. Plant foods (especially fruits and vegetables) contain antioxidants that combat oxidative stress and prevent the DNA damage that causes disease. The Mediterranean diet has been widely studied as a diet that combats inflammation and therefore reduces disease risk.
It’s also possible that people who adapt a plant-based diet are more health conscious overall and more likely to engage in other healthy behaviors.
I should be very clear that I do not support a vegan diet. Eliminating all animal products sets a person up for deficiencies in zinc, B vitamins, and iron, all very important for immune and nervous system function. Other common micronutrient deficiencies when following a fully plant-based diet (no meat) include iron, zinc, copper, carnosine, choline, iodine, phosphatidylcholine, various B vitamins (not only vitamin B12), omega-3 fatty acids, animal-based vitamin A (retinoids). Furthermore, when following a plant-based diet, some people often do get enough protein. A vegan diet requires supplementation, typically with a B complex, zinc, and iron, to fill the nutrient gaps, and why follow a diet that sets you up for nutritional deficiencies?
Bottom line here is that plant-based diets have been studied and proven to reduce disease risk. However, some people do not do well on a higher carb higher fiber diet that includes grains and legumes, and some people have trouble digesting certain fibers due to bacterial imbalances or other chronic conditions. That sad, t’s easy to adjust your plant-based diet to meet your needs.
People who have IBD and certain autoimmune conditions may have trouble eating fiber; they’re drawn to an animal-based diet and often experience great relief.
Carnivore and animal-based diets rose in popularity when Mikhaila Peterson, daughter of controversial psychologist Jordan Peterson, claimed the carnivore diet reversed many of her chronic health conditions. It took off from there on social media when doctors like Paul Saladino (“the Carnivore MD”) and famous carnivore instagram troll Shawn Baker (an MD who had his license revoked) starting touting the diet’s benefits for metabolic health, weight loss, disease prevention, and building muscle.
Despite the lack of studies, there is some validity to the claims that an animal-based diet can relieve chronic conditions. I’ve seen the carnivore diet work well for autoimmune, IBS, and IBD, probably because it’s the fibers and lectins in plant foods that bother people with said conditions. The issue, however, is the diet’s safety long term. Any diet that excludes such a huge array of foods is likely to cause long term problems like deficiencies.
Carnivore enthusiasts say meat is the ultimate superfood, and while meat does have a lot of benefits, there are problems with a high protein fiberless diet. First off, too much animal protein also stimulates the insulin and IGF-1 and growth hormone pathways that accelerate aging. Meat also activates mTOR pathways which also may reduce lifespan.
Secondly, too much meat intake alters the microbiome, which can accelerate aging and increase the risk of cancer and other aging-related diseases. The amino acids (protein) in meat lead to microbiome changes. Fiber is such an important nutrient for producing short chain fatty acids in the gut which help prevent colon cancer. And we don’t yet know the extent of damage to your microbiome when you remove fiber from your diet. Your gut bacteria need fiber to survive, so you’re basically starving them. When your bacterial colonies start to dwindle, you can’t digest your food as effectively, and a diverse gut biome is associated with a robust immune system.
Thirdly, plants contain important phytochemicals that not only nourish our gut bugs but provide us with important nutrients and antioxidants (vitamins A, C, E, zinc, selenium) that fight disease.
Fourth, while many on the carnivore diet claim they saw reductions in blood sugar, cholesterol, and blood pressure, many see the opposite (there we go again with there isn’t a one size fits all approach). An all-meat diet raises inflammatory markers and cholesterol to dangerous levels in some people, increasing risk for heart disease. Many carnivores, like Shawn Baker, are cholesterol deniers who say high cholesterol will not cause heart disease.
And some of the animal-based enthusiasts use shoddy “science” to back up their claims. Let’s take famous bio-hacker Dave Asprey who says you shouldn’t eat any phytic acid or lectins or oxalates that occur naturally in plant foods. The thing he conveniently omits is that many of these compounds are deactivated during cooking. He’s advising an entire population to cut out beneficial vegetables. Only people with chronic conditions like kidney stones or interstitial cystitis need to avoid said foods.
While my personal opinion is that a carnivore diet can have short term benefit, like reducing symptoms of an IBD or autoimmune flare, it is not safe to follow long term. And we just don’t have these studies yet. High-animal protein diets are unhealthy in the long term because a high meat intake accelerates fundamental aging processes. There is no longevity zone in the world where people live longer by eating lots of meat or animal protein.
The carnivore crowd often cherry picks studies to support their agenda, and that can confuse people, especially if they try the diet and experience negative side effects. And if we look at the whole of scientific studies, numerous studies show that people who follow a plant-based diet live longer and are healthier.
Conclusion
The answer to the great plant vs animal debate probably lies somewhere in between the two extremes. I cannot stress that there is no one size fits all approach to diet, but we do know the healthiest people on the planet follow a diet rich in plant foods and anti-inflammatory foods. More comprehensive and controlled studies are needed to fully understand the effects and implications of the carnivore diet.
Cutting out major food groups, whether meat or carbs, can have detrimental health effects. Humans thrive on a diverse diet. A vegan diet can feel great initially as you’re increasing more plant foods your body needs, but I don’t find it sustainable for human health long term. Similarly, the carnivore diet can clear up health issues and flares quickly but has longer term detrimental effects. Both extremes usually cause deficiencies in important nutrients over time.
My personal opinion is that both vegan and carnivore diets can be used for therapeutic purposes but not long term. In the end, however, a plant-based diet with whatever amounts of animal protein suits your health needs and lifestyle is the overall healthiest diet. It’s about balance.
Mary Vance is a Certified Nutrition Consultant and author specializing in digestive health. She combines a science-based approach with natural therapies to rebalance the body. In addition to her 1:1 coaching, she offers courses to help you heal your gut and improve your health. Mary lives in San Francisco and Lake Tahoe in Northern California. Read more about her coaching practice here and her background here.
