Plant-Based or Animal-Based Diet: Which Is Better?
Plant-Based or Animal-Based Diet
Plant-Based or Animal-Based Diet: Which Is Better?
Christopher Gardner, PhD: Glad to be here.
Jain: Let’s get right into this. There’s been a lot of talk, both in the lay media and in the scientific literature, on plant-based and animal-based diets. When it comes to an individual living with diabetes, does one diet make more sense than the other?
Gardner: I think this is one of those false dichotomies. It’s not all one or all the other. My favorite sayings are “with what” and “instead of what.” You may be thinking, I’m going to go for animal-based. I know it’s low-carb. I have diabetes. I know animal foods have few carbs in them.
That’s true. But think of some of the more and the less healthy animal foods. Yogurt is a great choice for an animal food. Fish is a great choice for an animal food with omega-3s. Chicken McNuggets, not so much.
Then, you switch to the plant side and say, “I’ve heard all these people talking about a whole-food, plant-based diet. That sounds great. I’m thinking broccoli and chickpeas.”
I know there’s somebody out there saying, “I just had a Coke. Isn’t that plant-based? I just had a pastry. Isn’t that full of plants?” It doesn’t take much to think about this, but it’s not as dichotomous as animal vs plant.
Jain: Obviously, there is a good understanding of what constitutes the diet. Initially, people said that animal-based diets are bad from a cardiovascular perspective. But now, some studies are suggesting that it may not be true. What’s your take on that?
Gardner: Again, if you think “with what” or “instead of what,” microbiome is a super-hot topic. That’s fiber and fermented food, which are only plants. Saturated fat, despite all the controversy, raises your blood cholesterol. It’s more prevalent in animal foods than in plant foods.
Are there any great nutrients in animal foods? Sure. There’s calcium in dairy products for osteoporosis. There’s iron. People can get too much iron, a pro-oxidant, at too high levels.
The American Heart Association, in particular, which I’m very involved with, issued new guidelines in 2021. They were very plant-focused. At the top of the list were vegetables, fruits, whole grains, and protein. Protein came mostly from lentils, beans, and grains.
Jain: That’s good to know. Let’s talk about protein. We often hear that somebody on a plant-based diet can never have all the essential amino acids and the amount of protein needed. Whether for general everyday individuals or for athletes or bodybuilders, you cannot get enough good-quality protein from a plant-based diet.
Is there any truth to that? If not, what would you suggest for everyday individuals on a plant-based diet?
Gardner: This one drives me up the wall. Please stop obsessing about protein. This isn’t a scientific answer, but watch the documentary Game Changers, which is all about vegan athletes. There are some pretty hokey things in that film that are very unscientific.
Let’s return to basics since we only have a few minutes together. It is a myth that plants don’t have all the amino acids, including all nine essential ones. I have several YouTube rants about this if anybody wants to search “Gardner Stanford protein.” All plant foods have all nine essential amino acids and all 20 amino acids.
There is a modest difference. Grains are a little low in lysine, and beans are a little low in methionine. Part of this concerns how much of a difference is a little low. If you go to protein requirements written up in 2005 by the Institute of Medicine, you’ll see that the estimated average requirement for adults is 0.66 g/kg of body weight.
If we recommended the estimated average requirement for everyone and everyone got it, by definition, half the population would be deficient. We have recommended daily allowances, which include two standard deviations above the estimated average requirement. Why would we do that? It’s a population approach.
If that’s the goal and everybody got it, you’d still have the tail of the normal distribution that would be deficient, which would be about 2.5%. The flip side of that argument is how many would exceed their requirement. That’s 97.5% of the population who would exceed their requirement if they got the recommended daily allowance.
The recommended daily allowance translates to about 45 g of protein for women and about 55 g per day for men. Today, Men and women in the United States get 80 g, 90 g, and 100 g of protein daily. They say, “I’m unsure if I need the recommended daily allowance. I feel like I’m extra special or above the curve and want to make sure I’m getting enough.”
The recommended daily allowance already has a safety buffer. It was designed that way.
Let’s turn to athletes just for a second. Athletes want to be more muscular and ensure they’re supporting their activity. Americans get 1.2-1.5 g of protein per kg of body weight daily, almost double.
Athletes don’t eat as many calories as the average American does. If they’re working out to be muscular, they’re not eating 2000 or 2500 calories daily. I have a Rose Bowl football player teaching assistant from a Human Nutrition class at Stanford. He logged what he was eating for his football workouts. He was eating 5000 calories per day. He got 250 g of protein daily without any supplements or shakes.
I do think this whole protein thing is a myth. As long as you get a reasonable amount of variety in your diet, you will have no problem meeting your protein needs. Vegetarians? Absolutely no problem because they’re getting dairy and some eggs and things. Even vegans are likely fine. They would have to pay a little more attention to this, but I know many very strong, healthy vegans.
Jain: This is so helpful, Dr. Gardner. I know that many clinicians, including myself, will find it very helpful, especially when we talk to our patients and counsel them on their requirements. Thanks for sharing that.
I have a final question for you. We know people on either side of the extreme: completely plant-based or completely animal-based. For most of us who have some happy medium, what would your suggestions be regarding the macronutrient distribution that you would recommend from a mixed animal- and plant-based diet? What would be the ideal recommendations here?
Gardner: We did a huge weight loss study with people with prediabetes. It was as low in carbs as people could go and as low in fat as people could go. That didn’t end up being the ketogenic level or the low-fat, vegan level. That ended up being much more moderate.
We found that people were successful on low-carb or low-fat diets. Interestingly, the protein content was very similar in both diets. Let’s not get into that since we just did a lot of protein. The key was a healthy, low-carb, or a healthy, low-fat diet. I think we have a lot of wiggle room there. Let me build on what you said just a moment ago.
I don’t think you need to be vegan to be healthy. We prefer the term whole-food, plant-based. You’re fine if you’re getting 70% or 80% of your food from plants. The additional benefit will not be large if you want to get the last 5%, 10%, or 15% all from plants. You might want to do that for the environment or animal rights and welfare, but from a health perspective, a whole-food, plant-based diet leaves room for some yogurt, fish, and maybe some eggs for breakfast instead of those silly high-carb breakfasts that most Americans eat.
I will say that animal foods have no fiber. Given what a hot topic the microbiome is these days, the higher and higher you get in animal food, it’s going to be hard to get antioxidants, most of which are in plants, and very hard to get enough fiber, which is good for the microbiome.
That’s why I tend to follow a whole-food, plant-based diet that leaves some room for meat and animal-sourced foods, which you could leave out and be fine. I wouldn’t go in the opposite direction to the all-animal side.
Jain: That was awesome. Thank you so much, Dr. Gardner. Here’s the final pearl of wisdom: When clinicians like us see patients with diabetes, what should be the final take-home message that we can counsel our patients about?
Gardner: That’s a great question. I don’t think it’s so much animal or plant; it’s a type of carbohydrate. Shan and colleagues have a great paper out of JAMA in 2019 or 2020. They looked at the proportion of calories from proteins, carbs, and fats over about 20 years and the subtypes.
Interestingly, protein from animal foods is about 10% of calories; from plants, about 5%; mono-, poly-, and saturated fats are about 10% of calories; and high-quality carbohydrates are about 10% of calories. What’s left is 40% of calories from crappy carbohydrates. We eat so many calories from added sugars and refined grains that are plant-based. Added sugars and refined grains are plant-based.
In terms of a lower-carbohydrate diet, there is ample room for cutting back on that 40%. What would you do with that? Would you eat more animal food? Would you eat more plant food? This is where I think we have a large amount of wiggle room. If the patients could get rid of all or most of that 40%, they could pick some eggs, yogurt, fish, and high-fat foods. They could pick avocados, nuts, seeds, and olive oil or have more broccoli, chickpeas, tempeh, and tofu.
There is a large amount of wiggle room. Can we please get rid of the elephant in the room? Plant food is all that added sugar and refined grain.
Jain: That was brilliant. Thank you so much, Dr Gardner, for joining us today.
This is Akshay Jain, signing off for Medscape.
Gardner: It’s been a pleasure, Akshay. Thanks.
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