There is often confusion on the topic of plant-based nutrition and what the scientific results tell us and how to interpret them. What emerges from the literature is that following a balanced diet without animal products or with a very low intake of animal products brings greater benefits to the body than an omnivorous diet. There are risk factors that have been known for decades for the onset of diseases and which are intertwined with each other and self-sustaining: obesity, diabetes, cardiovascular problems, tumors. The inflammatory state, hypercholesterolemia, high blood sugar, insulin problems, high blood pressure. Overall, the literature is now clear on the fact that those who follow veg diets have better results for these indicators, and therefore risk less. In essence, it is now scientifically consolidated that “more vegetal is better”, but the details of this “more vegetal is better” must be explained carefully.
Two scientific approaches
There are two approaches to evaluating the impact of a diet: we can study its statistical effects, i.e. compare for some indicators groups of people who follow different diets and see who at the end of a certain period has benefits and who less. In the case of the twin study published in JAMA on which the documentary produced by Netflix You Are What You Eat was based, participants were asked to start a vegan diet for 8 weeks to evaluate the first benefits. It is quite another thing to follow a diet for years.
Another approach is to study the biochemical mechanisms of how some substances interact with the functioning of our organism (the impact of free radicals, the dynamics underlying inflammatory processes and so on) and to infer that if a certain substance promotes inflammation it is better avoid taking it to reduce the risk of a certain adverse event occurring. Of course, an element to take into consideration will always be the type of vegan diet, whether balanced or do-it-yourself, and how long the person has been following this diet, a factor that varies from study to study.
Within these two approaches, some “confounding” factors must be considered that shuffle the cards.
The scientific results that reveal an advantage of “veg” diets are based on balanced diets, as per the guidelines. Perhaps not everyone knows that in Italy since 2018 we have published guidelines for plant-based nutrition, including children and weaning and services such as Planter of Botanical Cuisine based on these guidelines. We’ll talk more about it in the next episodes. Below is the interview with Carlotta Perego, content creator of Cucina Botanica.
Pay attention to the words
Scientific evidence on dietary regimes is obtained through one of these two approaches. In the first of the two, the choice of indicators to evaluate which diet “is best” is based on the results of research of the second type. In reality, a clarification needs to be made: it is not always so clear what is meant by a plant-based diet. An article published in Nature in 2022 examined the use of the terms plant-based, vegetarian and vegan in over 150 scientific articles published between 1992 and 2020 to understand exactly what type of “plant-based” diet was being considered, i.e. what types of foods can a plant-based diet include. Result: Many use this term interchangeably with vegan diet, others include a small portion of dairy products, still others emphasize a semi-vegetarian dietary pattern.
The crux of the matter
Having said that, what we can say today about plant-based diets is that it is not necessary to become completely vegan to see one’s levels of bad cholesterol, inflammation, insulin, known risk factors for various diseases, improve, or to see a reduction body and visceral fat levels. Drastically reducing the consumption of foods of animal origin also makes a difference. Clearly it is the overall quality of the diet, rather than the intake of a single macronutrient, that determines the reduction or increase in this risk. But it is equally clear that if you make the complete leap, switching to a completely plant-based but balanced diet, you are even better off. In other words, there is not only black and white, eating an egg every now and then or pasta all’amatriciana during the party with grandma or the cheese sandwich that time when there is nothing else in the mountain refuge, does not invalidate the everyday life of a plant-based diet. However, it is clear today to anyone who wants to honestly read the medical literature that vegans are those who statistically show the best values of all.
Thinking this way in terms of contamination is human. An anthropologist, Mary Douglas, wrote a text entitled Purity and Danger. An analysis of the concepts of contamination and taboo in the 1960s it became a point of reference for anthropological studies. It’s another thing to reason, perhaps reaching the same result, but with scientific evidence in hand.
Inflammatory processes
Progressive and constant states of inflammation over time are the basis of the onset of chronic-degenerative pathologies, such as obesity, metabolic syndrome, type 2 diabetes and cardiovascular diseases. In reality, however, we should not simplify, because inflammatory processes have complex dynamics and scientific research has been studying these aspects for years.
There are pro-inflammatory molecules that affect cardiovascular risk. Two of these are carnitine and choline, which once in the intestine are converted into TMAO, N-oxidized trimethylamine, derived from the metabolism of choline by intestinal bacteria, which in humans is mainly taken as dietary lecithin. TMAO promotes the accumulation of cholesterol in macrophages and, in agreement, a positive relationship has been found between high levels of TMAO and the incidence of major cardiovascular events. According to some studies, TMAO is an independent risk factor for atherosclerosis.
Saturated fats
Over the past decade, some of the most important scientific institutions, such as the International Agency for Research on Cancer (IARC) and the American Society of Oncologists (ASCO) have found that excessive consumption of trans fatty acids is associated with an increased risk to develop tumors of the oral cavity, pharynx, esophagus, breast and ovary. A clear summary can be found on the AIRC website: saturated fats, almost always of animal origin, including fish, if in high concentrations, have been associated with a greater incidence of atherosclerosis and heart problems. Many fatty acids favor the increase in LDL cholesterol levels, what we call “bad” because it accumulates on the walls of the arteries. Polyunsaturated fats include omega-3 and omega-6 (contained in oils, particularly corn and sunflower oils). Finally there are trans fats found in foods of industrial origin such as snacks, sweets and chips. The World Health Organization would like to eliminate its use by the food industry by 2023; today the threshold set for industrial products is 2.2 g of trans fatty acids for every 100 g of fat present.
Bad cholesterol, obesity and diabetes
As we will see in the third episode, all the meta-analyses of recent years confirm that balanced diets with low or no animal food content reduce levels of bad cholesterol in the arteries and fat. Obesity is a risk factor for many diseases. We cite just one example of a study in this sense: the summary of the IARC commission (International Agency for Research on Cancer) published in the New England Journal of Medicine in 2016.
The evidence in our possession so far has shown that obesity increases the risk of developing at least 12 forms of cancer, in particular those of the digestive system (esophagus, stomach, colorectal, liver, pancreas and gallbladder), in addition to tumors of the breast, uterus, ovary, thyroid, kidney and prostate. Statistically, those who eat “veg” have a much easier time keeping their weight under control because fat and visceral fat, the fat surrounding the internal organs, the most dangerous, are reduced.
Inquiry into food and science. Second episode out of seven.
To know more
Vegan diet and omnivorous diet. Investigation into food and science, episode 1