Debunking Dietitian’s Criticism of the Frugivore Diet with Biology: The Devil Is in the Details!

Turns out the natural human diet is very similar to that of all apes (which shouldn’t really surprise us, as humans are classified as great apes, too) and is based on fruits: a frugivorous diet – or “frugivore diet.” And with the growing popularity of such fruit-based diets and raw vegan diets, the number of critical voices, particularly by nutritionists, grows, too.

However, nutritional sciences seem to ignore adaptations related to diet and characteristics of the human body that have evolved as a response to foraging and diet. This is why the natural approach to our species’ biological diet might not be fully understood by the perspective of nutrition alone – which becomes apparent when nutritionists and dietitians evaluate our species’ natural diet. It’s like conventional medical practitioners talking about natural medicine and healing…

Read also: Are humans really frugivores?

Descriptions of the frugivore diet, such as “they consume foods that can be foraged in nature,” leave out a crucial component that could lead to misunderstandings and paint a wrong picture: The statement is true, but humans do not live in their natural habitat. So, there is much more to understand about our natural diet, especially regarding human ecology.

To explain the classic arguments against the frugivore diet, I felt like it was time to respond to a typical article. I chose the latest article on the frugivore diet and answered with my take as a biologist on a “dietician’s take” on the frugivore diet (which she does not seem to comprehend fully) and questions the approach of comparing humans to chimpanzees when it comes to diet.

Let’s start with the classic myth number 1:

“A frugivore diet does not contain enough protein!”

The author, who is a registered dietitian nutritionist, suggests eating chicken and beef because fruits, greens, and nuts do not contain sufficient protein. She says,

“Fruit doesn’t contain much protein or fatty acids (avocado and coconut are the exceptions on the fat front).” but then admits that “if you were really diligent about incorporating nuts, seeds, and roots, you might be able to scrape by and meet your very basic protein needs. However, this won’t be easy or sustainable for most. And if you have higher activity levels or metabolic needs? It would likely be impossible to meet your increased protein needs.”

Since a frugivorous diet meets the Recommended Dietary Allowance (RDA) of protein, this is not a valid argument. Why? Let’s look at what the teachings of nutritionists concerning nutrient recommendations really mean:

The RDA is the “average daily level of intake sufficient to meet the nutrient requirements of nearly all (97–98%) healthy individuals” This means, according to renowned Stanford prof Christopher Gardener, that using the RDA “is a population health approach, so that if everybody were to get that amount (the RDA), almost no one would be deficient… It was built in to recognize that some people would need more“, and he emphasizes that on an average American diet, people get way too much protein by “just eating food, not even trying.”

But let’s look at the protein content of a natural frugivorous diet, which is based on tropical fruits, nuts, and green: 2000- 2500 calories worth of food contain around 50-55 grams and, thus, reaches the RDA of 0.8 grams per kg of body weight. Despite common perception, fruits do contain an amount of protein that counts towards the overall intake of protein in our diet! Tropical fruits are much higher in amino acids than temperate fruits. Most tropical fruits contain around 2 grams per 100 grams, with a variation from around 0.8-2.4 grams. Find a list of high-protein fruits here.

All raw foods, including fruits, contain some amount of proteins. Many larger mammals in the wild are plant-eaters. And chimpanzees in the wild get their proteins mostly from tropical fruits and tender leaves. The amount of proteins in a fruit-based diet largely depends on fruit quality but also on foods like nuts, greens, etc.

Classic myth number 2:

“There’s too much sugar in fruits!”

The second common misconception that is mentioned in the article is sugar in fruits:

“While fruit has numerous health benefits, it still contains sugar—and excess sugar can be a problem, especially for those with blood sugar regulation issues (think diabetes or hypoglycemia). Our pancreas produces insulin that, when released into the blood, helps to regulate the amount of sugar circulating through our system.”

Weirdly, this dietitian – like most nutritionists – worries about sugar in fruits when eaten in large quantities, despite the fact that consuming high-sugar fruits has shown to be beneficial for health and has anti-diabetic effects. I wonder why there are very few individuals in this field of profession who talk about the innumerable studies reporting on the anti-diabetic effect of fruits… I wonder how many nutritionists are aware that fruit has been shown to be beneficial for insulin regulation and that the sugar in fruits is around 50% fructose, which does not require insulin to enter cells and does not spike blood sugar levels or insulin spikes. And no, fructose in fruit is not harmful: Studies that report negative effects of fructose concern isolated high-fructose syrups. Fruits do not show to have the same effects – quite to the contrary:

Fruits have been shown to be the single most important dietary factor for good health. Surprised? It’s something we rarely hear about. It is, however, what we can read in renowned scientific journals. Knowing about our frugivorous nature, it is no surprise that fruits have been shown innumerable times to have important health benefits. A diet deficient in fruit is one of the main risk factors for poor health and increased mortality (Falcomer et al., 2019). 

It’s also contradictory to suggest balancing out meals (and carbs) by substituting fruits with starchy foods, like rice, beans, and quinoa – which contain more sugar than sweet fruits:

“From there, balance out your fruits and veggies at each meal by adding three to six ounces of a protein (chicken, fish, beef, tofu), up to a cup of a high-fiber starch (quinoa, brown rice, sweet potatoes, beans), and up to two tablespoons of some healthy fats (olive oil or nuts). “

Complex carbs contain the same molecules as simple carbs but bonded to each other. They form string-like polysaccharides. The individual sugars within those strings carry the same amount of calories as the single sugar molecules in sweet fruits do – just without the taste! This is why starches taste bland unless we cook them and break them into smaller pieces by heating them. What this means is that just because carbs taste sweet, they are not “worse” in terms of health and calories. A handful of rice (dry weight) contains approximately the same amount of sugar molecules and calories as a handful of sweet sugar (dry weight)! 100 grams of banana contains 20 grams of sugar, while 100 grams of cooked rice contains 44 grams of sugar. On top of that, we are prone to overeat complex carbs (like grains and starches) much more than sweet carbs in fruits – fructose and glucose. Simple carbs from fruits taste sweet because our taste receptors identify the simple sugar molecules (monosaccharides or disaccharides).

So why substitute our natural carb source with a carb source that is not edible in its natural state and, even when cooked, contains more anti-nutrients and fewer nutrients? From a nutritional standpoint (and biological standpoint), this does not seem to make a lot of sense. If anything, we should consider substituting cooked complex carb foods with more sweet, fleshy raw fruits that are our evolutionary staple foods. Read more here. And besides, humans have not evolved to be hooked on cooked food – quite to the contrary, we just seem to slightly tolerate cooked food better immunologically than other species (yes, cooked food triggers immune responses). Read more here. Just to complete: The chicken (protein food) topped with olive or nut oil (fats), which are heated or processed foods, are nutritionally substitutes for nuts – our natural, raw food source (B12 is missing in nuts, but discussed below).

Read also: Why it’s the tropical fruits that humans need

Common misconception number 3:

“Chimpanzees eat meat, which is why it’s natural for us, too.”

The dietitian also has a take on the biological aspects of our diet:

“Just to respond to the notion that we should all be getting back to our roots of eating like gentle fruit-loving apes…I’m guessing the people making this claim have never seen the videos out there of chimpanzees hunting and eating other monkeys. “

Now, here is where the devil lies in the details and where understanding the chimpanzee diet is necessary to draw dietary conclusions. For example, the chimpanzee dietary classification and the role of meat in chimpanzee nutrition must be understood to get a better picture. Just to summarize a few key points:

• There is a social component in hunting among male chimpanzees.
• Hunting is relatively rare, rather than a frequent behavior. So much so that apes were always considered “vegetarian” by locals – given they live in natural habitats and have enough food sources, I assume.
• Chimpanzees eat only 1-2 % of meat on average. There is a debate about whether all individuals and populations consume meat at all.
• Meat is not considered as an obligate protein source for them, but that their main protein sources are greens and nuts.
• Bonobo chimpanzees – which are most similar to humans – have a diet even higher in fruit and lower in animal sources than chimpanzees.

Besides studying our closest relatives’ diet, it is also crucial to consider our own instincts: I wonder, how many humans could hunt that beef and chicken (suggested foods by the author) themselves? Are we really meat-eating animals? Do we like raw meat? While we can learn a lot from apes, no one claims that we are identical… we are not. We differ slightly more than 2% or so 🙂

Let’s complete with other common nutritional concerns:

“The frugivore diet is too low in some micronutrients.”

To sum up nutritional concerns the dietitian states

“Additionally, while fruit is high in certain nutrients, it’s lacking in others—and a fruit-based diet increases the likelihood of major nutrient deficiencies. For example, most fruits are not good sources of iron, zinc, vitamin D, calcium, iodine, or vitamin B12.”

While some of the concerns are valid, again, the devil is in the details!

I have written about the risks and nutritional pitfalls of a raw fruit-based diet before, and allow myself to copy-paste some parts here. I also elaborate on why deficiencies can be a problem and on how to minimize those risks. And more importantly, in the context of this article, I explain why those concerns do not indicate that the natural human diet isn’t frugivorous! Let’s go:

Fruit-based frugivorous diets can bring tremendous health benefits in the short term. But when adopting a raw diet in the long run, there are some potential concerns about nutritional deficiencies, in particular protein, B12, omega-3, iodine, calcium, and iron. 

How valid are those concerns?

• “A fruit-based diet lacks vitamin B12“: Vitamin B12 has to be supplemented on all (or most) vegan diets, which has to do with microbiome and antibiotics and pesticide use in our modern world and the cobalt content of our soils and foods. All of those limiting factors affect not only humans but also farm animals, which are being supplemented with vitamin B12 if needed, too. Read more about B12 here. Newer research suggests that there is B12 in bananas, however, this information is still very limited.
• “A fruit-based diet lacks iodine“: In nature, iodine is primarily present in the sea and the environment near the sea – for example, edible greens from the sea are a rich source of iodine. Getting this element is not so much a question of the type of food you are eating but where it has been growing. For example, we can get iodine just by breathing in marine air. On the other hand, milk (which is often promoted as an iodine source) from the iodine-poor Alpes mountains originally was not a good iodine source for the locals. In short, this nutrient needs to be supplemented when living in an iodine-poor environment. Whole populations of countries (i.e., Switzerland) living in iodine-poor areas are supplemented via added iodine table salt – which shows that getting iodine depends more on the environment than on the types of foods.
• “A fruit-based diet is low in calcium“: Fruits contain plenty of calcium. Calcium absorption, however, depends largely on a healthy microbiome and sun exposure (vitamin D and K2), which is why many people on calcium-heavy diets in countries without sufficient sunshine suffer from low bone density and weak teeth.
• “A fruit-based diet is low in iron“: A frugivorous diet contains enough iron in greens, nuts, and even fruits. One key factor for getting iron is the high vitamin C content of fruit-rich diets, which helps absorb non-heme iron. Generally, absorption and gut health are key for any successful diet.
• “A fruit-based diet is low in zinc“: Nuts are a good source of zinc. For example, 5 Brazil nuts alone contain around 4 mg of zinc, which is half of the RDA for women, which is 8 mg of zinc per day. 100 grams of cashew contain 5-6 mg of zinc. When we add greens and tropical fruits into the equation, which contain around 0.5-1 mg of zinc per pound, we can reach the RDA, which is, as explained above, enough for most people.
• “A fruit-based diet is low in omega-3 fatty acids“: Some tropical fruits contain good amounts of Omega-3s. Examples are papaya and açai berry. Read more here.
• “A fruit-based diet is generally nutrient-deficient“: This point is not that straightforward to answer, because there are a lot of factors at play that can result in deficiency! Here, we are dogma-free and do not want to downplay the potential risks that can come along with a fruit-only diet, especially when we don’t know exactly what we are doing! There are a few points that are often ignored and can turn into deficiencies:

• Fruit-based diets must be based on tropical fruits. Access to high-quality, tropical fruits is, thus, decisive for the success of a fruit-based diet.
• Humans are naturally frugivores, not fruitarian. Frugivores do not only eat fruits, but greens, nuts, and tubers.
• We don’t live in our natural, tropical habitat. On top of that our environment is degraded, which brings a lot of shortcomings in nutrition. Due to this, we need to supplement nutrients on a vegan diet (but also on other types of diets). This is often denied in raw communities. Read also our article on supplementation.

As a consequence of living in a sub-optimal environment (and a degraded, polluted one), we can only get as close to a natural human diet as possible while acknowledging the shortcomings and accounting for them. The need to take supplements depends on the area you live in, the quality of food you can access, and how healthy (or pre-damaged by toxins and diet) you are. After all, the food sources that frugivores get in the wild generally contain more nutrients.

There are quite a few things to consider for a successful and sustainable frugivore diet. There are common mistakes that increase the risks of deficiencies that are commonly associated with a fruit-based diet (see below), that can be avoided! Also, check our guide for this purpose. However, despite all precautions, to avoid running into trouble in the long run, you need to check for deficiencies regularly with your healthcare provider. We all come from a past of predispositions, toxic burdens, and accumulated damages from a lifetime (and even generations) of living in unnatural habitats and eating sub-optimal foods. This can be a cause of preexisting deficiencies, and that might have to be addressed and need to be taken seriously. Some people hardly have complications when venturing into the human natural diet; others have a bumpy road!

All that being said, there are many living proofs of healthy and athletic people living a raw diet and fruit-based diet over decades. And while this does not mean that it works for everyone, it does indeed show that it is possible under the right circumstances! In any case, it is highly advisable to have your nutrient levels checked frequently – on any diet!

Conclusion: Let’s stop ignoring the elephant in the room – the natural human diet!

Every species has a natural diet. We study some of them but do not look at our own species’ diet. The biological human diet might be more complex than studying apes and our instincts, but it is borderline insane that this natural concept is not even mentioned in nutrition sciences. It’s time to acknowledge the existence of a natural human diet, a diet biologically appropriate for our species, and study it in depth.

Instead of dismissing the frugivore diet, what about really understanding the nuances concerning fruit types, food quality, and ecology?

It’s also time to acknowledge that many foods we eat today are not our “evolutionary foods”. Nonetheless, I do agree that fruit-based diets and raw diets can go wrong if not done properly, with the right quality of foods and the types of foods that we have evolved to eat.