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Pros and cons of the vegan diet | Yamamoto® Nutrition
Pros and cons of the vegan diet Yamamoto® Nutrition

Pros and cons of the vegan diet
Yamamoto® Nutrition

Date: December 29, 2023

Where the vegan diet comes from

Per several years there has been discussion in the most disparate ways, sometimes harsh and with acrimonious implications, on the opportunities of modifying the prevailing eating style since the end of the last disastrous war (as they all are) in which a relative well-being established in the "Western" world ” has allowed access to foods of animal origin, once available only to the wealthier and wealthier classes. The increase in Protein of animal origin, undoubtedly better in terms of richness of essential amino acids, in the daily diet has allowed various improvements in the health of the populations who have had access to them, both from the point of view strictly linked to the improvement of overall health (the increase in life expectancy has undoubtedly benefited from this contribution linked to a more complete and satisfying diet) but also and above all from the improvement of the overall physical structure. Regarding this last point, it is enough to remember the notable increase in average height recorded over the last 70 years in all Western populations, and not only.

Obviously the aforementioned improved conditions do not depend only on the quality of the diet to which access to products of animal origin favored by better economic conditions has certainly contributed, there are certainly many other factors that have favored this improvement, but equally obviously we could consider them all in same way.

As often happens, it is, unfortunately, easy to fall into the opposite problem, whereby both the uncontrolled development of intensive livestock farming which corresponds to low-priced (but also very poor quality) food of animal origin, and the economic policies of many "rich" states ” who found themselves faced with the need to offer high-calorie but low-cost foods to manage the needs of those forced to emigrate whose conditions were (in many cases it is still a very current problem) disastrous, so in recent years the notable problem of excess food, especially poor quality food derived mainly from animals. A striking example is the policy of the US government in the 1960s which, in order to manage the significant Hispanic immigration from South America, gave rise to a series of high-calorie and very low-cost foods which were defined by many as "junk food", a definition which later broadened until a series of foods supplied by restaurant chains classified in a specific way are identified.

The large series of now well-established and evident adverse effects resulting from excess energy and animal products has led the scientific community to question itself and produce a long series of studies seeking a comparison between diets, trying to give a diet license “healthier”. It seems obvious to point out that to date, after an immense quantity of studies produced, the composition of the podium of dietary models has not been concluded but we are certainly able to have much more information, which is essential for evaluating the individual administration of dietary protocols in a way absolutely free from sympathies or, even worse, from fanaticism always present in a period dominated by the presence of various "influencers" who put their opinion before the equidistant scientific vision.

In order to have a broader overview, I report below the results of some studies certainly not influenced by fashions, fanaticism and the like, and therefore capable of providing food for thought.

Pros and cons of the vegan diet

A vegetarian diet is associated with many health benefits due to its higher fiber content , folic acid , vitamins C and E , potassium , magnesium and many phytochemicals and a higher unsaturated fat content. Compared to other vegetarian diets, vegan diets tend to contain less saturated fat and cholesterol and more Fibre. Vegans tend to be leaner, have lower serum cholesterol and lower blood pressure, reducing the risk of heart disease. However, eliminating all animal products from your diet increases the risk of certain nutritional deficiencies . Micronutrients of particular concern (known deficiencies) for vegans include vitamins B12 and D , calcium , and long-chain n-3 (omega-3) fatty acids .

Unless vegans regularly consume foods enriched with these nutrients, appropriate supplements should be consumed. In some cases, vegans' iron and zinc status may also be a cause for concern due to the limited bioavailability of these minerals.

  • Cardiovascular diseases : the greater consumption of fruit and vegetables decreases blood cholesterol and blood pressure, making vegans more protected, probably because they tend to be thinner, a condition certainly associated with a decrease in the incidence of these pathologies (the opposite of what happens in subjects obese).

  • Cancer : Fruits and vegetables are known to contain a complex mixture of phytochemicals that possess potent antioxidant and antiproliferative activity and show additive and synergistic effects. Phytochemicals interfere with several cellular processes involved in cancer progression, so they are expected to protect against processes that trigger various tumors, but with this wide range of phytochemicals useful in the vegetarian diet, it is surprising that Population studies have shown no more pronounced differences in cancer incidence or mortality rates between vegans and omnivores, new evidence suggests that low vitamin D, a problem often reported in vegan populations, is associated with increased risk of cancer. More research is needed to explore the relationship between consuming plant-based diets and cancer risk because there are many unanswered questions about how diet and cancer are linked. To date, epidemiological studies have not provided convincing evidence that a vegan diet offers significant protection against cancer.

  • Bone Health : Inadequate protein intake and low calcium intake have been shown to be associated with bone loss and hip and spine fractures in older adults. Adequate calcium intake can be a problem for vegans. The higher risk of bone fracture observed in vegans appears to be a consequence of a lower average calcium intake. No difference was observed between the fracture rates of vegans who consumed > 525 mg of calcium per day and those of omnivores although the calcium provided by plants often presents considerable difficulties in assimilation.

  • Nutritional deficiencies : Diets that do not include fish and eggs generally lack long-chain n-3 fatty acids, in fact compared to non-vegetarians, vegetarians, and especially vegans, tend to have lower blood concentrations of EPA and DHA. Taking supplements is not always able to fill this gap, an accurate distribution of doses and a choice of source of omega-3 are necessary. As has been said about vitamin D, another problem that vegans encounter is linked to the intake of iron: it is well established that the absorption of heme iron is greater than iron from vegetables; but hemoglobin concentrations and the risk of iron deficiency anemia are similar for vegans compared to omnivores and other vegetarians, probably due to the significant content of vitamin C and folic acid in their diet. However, serum ferritin concentrations are lower in some vegans, while the average values ​​tend to be similar to the average values ​​of other vegetarians but lower than the average value of omnivores, it is not clear why. Compared to lacto-ovo-vegetarians and omnivores, vegans typically have lower plasma vitamin B12 concentrations and higher plasma homocysteine ​​concentrations. Elevated homocysteine ​​levels have been considered a risk factor for cardiovascular disease and osteoporotic bone fractures. Vitamin B12 deficiency can produce abnormal neurological and psychiatric symptoms, mood disorders, motor disorders, and difficulty concentrating. Furthermore, children may experience apathy and growth difficulties, and macrocytic anemia is a common feature at all ages. Another well-known deficiency among vegans is that of zinc. Phytates, a common component of grains, seeds and legumes, bind zinc (like many other cations) and therefore reduce its bioavailability. However, a sensitive marker to measure zinc status in humans has not been well established, and the effects of marginal zinc intakes are poorly understood.

Interesting very recent study (a 2022 meta-analysis) found several findings worth evaluating carefully: The objective of this systematic review and meta-analysis was to examine the effect of vegan diets (≥ 12 weeks) on risk factors cardio-metabolic in people with overweight or type 2 diabetes. Compared to control diets, vegan diets reduced body weight, body mass index (BMI), glycated hemoglobin, total cholesterol, and low-density lipoprotein cholesterol. No effects on blood pressure, high-density lipoprotein cholesterol and triglycerides were identified. In essence, adhering to a vegan diet for at least 12 weeks can be effective in individuals with overweight or type 2 diabetes to induce a significant decrease in body weight and improve blood sugar. Some of these effects may be due to differences in macronutrient composition and energy intake in vegan versus control diets. This study concludes, as usual, by calling for further research on vegan diets and cardio-metabolic health.

Some of the studies that included data on changes in body composition found that loss of lean mass (often present during a diet) accounted for 12%-40% of total weight loss in response to vegan dietary interventions, therefore, the recommendations of Following a vegan diet should be optimally combined with recommendations to be physically active to prevent loss of lean body mass.

Regarding vitamin B12 deficiency, a 2014 study (review) reported several vascular studies that demonstrated an impairment of arterial endothelial function and an increase in carotid intima-media thickness as surrogates of atherosclerosis in such metabolically deficient populations. vitamin B12 (European and Chinese vegans but especially from Hong Kong and India where vegans rarely take vitamin supplements), but not in lacto-vegetarians in China. Vitamin B12 supplementation has a favorable impact on these vascular surrogates.

Conclusions on the vegan diet

In conclusion the hypothesis that the health benefits of vegan diets (vegetarian diets without dairy or egg products) are increasingly popular, particularly among young women (2%-4% prevalence).

Preference for such nutritional choices centers on better care of the earth's resources and the environment, ethical questions about animal care, use of growth stimulants and antibiotics for animal husbandry, concern for animal-borne diseases, potential allergies and intolerance to lactose from dairy products. While evidence from epidemiological studies over the past two decades suggests that most balanced vegetarian diets are nutritionally adequate and associated with a lower risk of coronary heart disease and stroke, the advantage of a strict vegan diet over ovo-lacto-vegetarian remains unproven and therefore if one wishes to opt for the latter choice, great caution is deemed necessary, a rigorous intake of supplements relating to the deficient nutrients and above all avoiding rigorous adherence in adolescents and/or even more at younger ages where significant risks of nutritional deficiencies harbingers of lower bone density and height have been reported. Vegetarians showed less pronounced nutritional deficiencies but, unexpectedly, a less favorable cardio-metabolic risk profile.

Scientific references

• Health effects of vegan diets. Craig WJ. Am J Clin Nutr. 2009 May;89(5):1627S-1633S.
• Vegetarian, vegan diets and multiple health outcomes: A systematic review with meta-analysis of observational studies. Dinu M, Abbate R, Gensini GF, Casini A, Sofi F. Crit Rev Food Sci Nutr. 2017 Nov 22;57(17):3640-3649.
• Effects of vegan diets on cardiometabolic health: A systematic review and meta-analysis of randomized controlled trials. Termannsen AD, Clemmensen KKB, Thomsen JM, Nørgaard O, Díaz LJ, Torekov SS, Quist JS, Faerch K. Obes Rev. 2022 Sep;23(9):e13462.
• Growth, body composition, and cardiovascular and nutritional risk of 5- to 10-y-old children consuming vegetarian, vegan, or omnivore diets. Desmond MA, Sobiecki JG, Jaworski M, Płudowski P, Antoniewicz J, Shirley MK, Eaton S, Książyk J, Cortina-Borja M, De Stavola B, Fewtrell M, Wells JCK. Am J Clin Nutr. 2021 Jun 1;113(6):1565-1577.
• Vegan diet, subnormal vitamin B-12 status and cardiovascular health. Woo KS, Kwok TC, Celermajer DS. Nutrients. 2014 Aug 19;6(8):3259-73.
• Debunking the vegan myth: The case for a plant-forward omnivorous whole-foods diet. O'Keefe JH, O'Keefe EL, Lavie CJ, Cordain L. Prog Cardiovasc Dis. 2022 Sep-Oct;74:2-8.

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