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Fei
Aug 1, 202310 min read

What is the Diet that Prevents the Greatest Killer Worldwide - CVDs?


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This article was originally written by Fei Li as a paper for the University of Canterbury in Christchurch, New Zealand on 9 November 2022.


Introduction

Health is the foundation of a happy life. Besides unpredictable accidents, unhealthy lifestyles have been taking people’s lives yearly. Globally, 55.4 million people died in 2019, and 55% were caused by chronic diseases (World Health Organization). Figure 1 shows that the biggest killer worldwide is cardiovascular diseases (CVDs), which caused 18.56 million deaths and accounted for 33% of overall death causes. The death toll is equivalent to a plane with 70 passengers taking off every two hours and crashing, killing everyone on impact. It is a shocking number, and the causes and preventions of CVDs deserve to be studied for the well-being of humankind. Studies have shown a close association between diet and CVDs development. An animal-based diet causes a higher rate of heart disease, whereas a healthy plant-based diet is positively linked to a lower risk of CVDs (Fraser). The research will introduce the context and causes of CVDs, followed by a detailed diet analysis that lowers the chances, and lastly, discuss the challenges and barriers to diet change.



Figure 1. Number of deaths by cause (Our World in Data)



CVDs

CVDs refer to all kinds of heart and blood vessel disorders, causing coronary heart disease, cerebrovascular disease, heart attack, heart failure and stroke (WHO). Research has shown it is not a single factor that causes CVDs, but the core reason for CVDs is atherosclerosis, a symptom of the fatty plaques accumulating on the walls of the arteries (Heart Research Institute NZ). Plaques, composed of fat, calcium and other chemicals, solidify over the years, narrow the artery’s entrance and limit the blood flow. Atherosclerosis can happen anywhere in arteries in the body, causing limited or blocked blood supply. However, the most harmful effect occurs in two main coronary arteries that go through the brain and the heart (Heart Research Institute NZ). The former results in heart attack, and the latter causes stroke, two diseases that account for 85% of deaths from CVDs (WHO).


The causes of atherosclerosis can be divided into two categories: unchangeable factors and manageable factors. Unchangeable factors include increasing age, gender, family history and ethnicity (Heart Research Institute NZ). The risk of CVDs increases with age, and the group aged 75+ shows a higher risk of getting CVDs. Women have a slightly lower risk than men. If close relatives like parents develop CVDs at a young age, it increases children’s odds of infecting CVDs. Besides, Māori people have a greater likelihood of developing CVDs (Heart Research Institute NZ). Apart from the non-variable factors, variable factors like lifestyles show a close correlation with risks of CVDs (Fraser). The critical behavioural risk factors include unhealthy diet, lack of exercise, tobacco smoking and use of alcohol. What we eat and drink accounts for 75% of the four modifiable components, demonstrating the significance of a healthy diet for preventing CVDs and prolonging life. Both eastern and western cultures have sayings that stress the importance of diet with health. There is an idiom in Chinese that states, “病从口入” (Illness enters by the month) and an expression in English that forms, “You are what you eat”. It is generally acknowledged that a good diet promotes health and vice versa.



Healthy Plant-based Diet

The discussion around a balanced and healthy diet to prevent CVDs has been controversial. However, it is a common consensus that eating more fruits and vegetables, eating good fat (e.g. nuts, avocado), and cutting tobacco and alcohol use reduces the CVDs risks (HRI-NZ). This section analyses the influence of protein source, serum cholesterol, tobacco and alcohol use on CVDs and introduces a diet that reduces CVDs risk.



Animal Protein vs Plant Protein

Multiple studies illustrate that plant-based consumers have a lower risk of heart disease (Fraser, Tuso et al.). The result was enhanced by Song et al.’s cohort study with U.S. nurses and professionals in the healthcare industry. It reveals the impact of animal and plant protein intake on overall mortality (Song et al.). Animal protein comes from processed and unprocessed red meat, fish, eggs and dairy products, and plant protein can be found in cereal, bread, nuts and seeds, legumes, fruits, vegetables, etc. The result shows that animal protein is favourably linked to CVDs mortality. In contrast, plant protein is inversely associated with CVDs mortality, with the correlation more evident among the group with at least one lifestyle risk factor (Song et al.).


Different animal protein sources have varying degrees of adverse effects on cardiovascular health, and almost all kinds of meat contribute to developing CVDs. With every 10% increase in animal protein, the CVDs mortality risk rises by 8% (Song et al.). Protein from processed and unprocessed red meat has a more harmful effect on cardiovascular health. The CVDs mortality decreases by 34% when 3% of energy from plant protein replaces the same amount of animal protein from processed red meat and 12% when substituting unprocessed red meat (Song et al.). Another landmark report about protein intake is Kwok et al.’s study of the impact of a vegetarian diet (no red meat, fish, or pork) on causing CVDs and mortality (Kwok et al.). Compared with non-vegetarians, vegetarians are exposed to a 29% lower risk of coronary heart disease (CHD).


It is noticeable that protein from processed meat and red meat poses a more significant health risk other than causing CVDs. In 2015, a group of 22 experts from 10 countries in the World Health Organization (WHO) released a report that divided processed meat consumption as carcinogenic to humans, same group as tobacco smoking, and classified red meat as probably carcinogenic to humans (International Agency for Research on Cancer). WHO defines processed meat as “meat that has been transformed through salting, curing, fermentation, smoking, or other processes to enhance flavour or improve preservation” and red meat as “all mammalian muscle meat, including beef, veal, pork, lamb, mutton, horse, and goat” (WHO).


Research on protein intake has raised public awareness to re-examine the types of healthy protein. Beef and peanuts have the same protein content of 26g per 100g. Chicken and flaxseeds share the same protein content of approximately 20g per 100g. Pumpkin seeds show a high protein content of 33g per 100g, higher than red meat and fish.



What about eggs?

High serum cholesterol is found to be a leading risk factor for CVDs. Multiple observational studies from 1978 to 2016 revealed that total cholesterol was significantly lower in vegans than in others (Radnitz et al.). The yolk of an egg is where saturated fat and cholesterol are most concentrated. Eggs can spontaneously hatch chicks in 21 days without outside energy (different from infants who need mothers’ nutrition to grow), and the yolk content is almost exclusively saturated fat and cholesterol. The fat and cholesterol from the yolk enters the bloodstream and wraps around red blood cells, and the blood thus becomes thick and sticky, changing hormone levels and raising cholesterol levels (What the health). Song et al.’s cohort study shows that with 3% energies from egg protein substituted with plant protein, the CVDs mortality rate reduces by 19%.



Smoking and alcohol?

Besides daily eating habits, tobacco smoking and alcohol use are two significant risk factors for CVDs (Nascimento, Bruno R. et al.). Multiple studies have shown that smoking significantly associates with CVDs risks. Smokers increase CVDs mortality rate by 197% compared to non-smokers (Ricci et al.). And the result has been consistent with Mons et al.’s research on the positive impact of smoking cessation on CVDs among aging generations (Mons et al.) and Pirie et al.’s study on the benefits of stopping smoking for CVDs risks for women in the UK (Pirie et al.).


Alcohol consumption is another risk for CVDs. Alcohol consumption over the past 12 months and the predominant consumption of solid alcohol shows a positive correlation with CVDs development (Viktorova I.A. et al.). Ricci’s study suggests that an increased risk of stroke has been connected with alcohol use (Ricci et al.).


Based on the positive connection of CVDs with animal protein, high serum cholesterol, tobacco smoking and alcohol use, a balanced diet that prevents CVDs development is a healthy plant-based diet that excludes the four diet risk factors (animal protein, high cholesterol, alcohol, and tobacco).



Challenges of Changing Diet

With more research results on plant-based diets to well-being, there is a rising trend in the number of vegans and vegetarians. The proportion of vegetarians in the United States has increased from 0.4% to 3.5% of the overall population during the previous two years (Meyer). Likewise, the number of vegans in the United Kingdom has tripled in the last five years, and New Zealand and Australia follow the same trend. If the rising rate maintains, one out of ten people worldwide will be vegan in the coming ten years (Meyer). However, changing to a plant-based diet has challenges and barriers, including the pleasure of eating meat, nutrition concerns and family/social pressure.


Among all obstacles, the pleasure of eating animal products and the difficulty of quitting them come first (Fehér et al.). It has been challenging to change a diet habit for decades. People with an open mind who develop their health consciousness with time and the motivation to stay healthy show positive association with adopting a healthy plant-based diet (Larsson and Orsini). Furthermore, evidence indicates that higher socioeconomic classes show reduced numbers of smokers and alcohol users. They are more likely to accept advanced health knowledge and adopt a healthy plant-based diet (Chang-Claude et al.). Some people may argue that “we are born as carnivores/omnivores”. It seems that most people follow an animal-based diet, but looking back, it is not the case. Infants are fed breast milk in their early days and gradually move on to eat liquid food, primarily vegetables. Until one day, newborns are fed their first taste of the meat by their parents, who have passed along the notion from their parents that animal-based foods are beneficial for growth. What we eat is not a conscious choice but is shaped by the environment. Gradually, eating an animal-based diet becomes an attachment and hard to break.


The worry of not having enough nutrients is the second biggest concern for adopting a healthy plant-based diet. Traditional study of food has focused on nutrient abundance, and modern survey about healthy food has included the factors of both rich in nutrients and friendly to health. [A1] [A2] Meanwhile, animal-based and plant-based diets have found no significant difference in protein supply. Specific vitamins like B12 might be a concern as it is not popular in plant-based products; however, research has revealed that algae are a good source of B12 (Fehér et al.).


Another barrier is the inconvenience of eating at home and the limited choices of dining in restaurants. The diet change may trigger disapproval and tension in the family, which can create further obstacles to maintaining the diet, especially when other family members don’t follow the initiative. Meanwhile, food plays a social role in the business environment and personal life. Interpersonal relationship pressure and limited plant-based options increase the difficulty of persisting on a healthy diet.


With the barriers discussed, a change in diet begins with the willingness to have a healthy lifestyle and the determination to take care of oneself and their family. Due to the popular belief that animal protein is crucial in supplying adequate nutrients to human health, adopting a healthy lifestyle is likely to take longer than expected.



Conclusion

This study introduces a healthy plant-based diet that reduces the risks of the disease that accounts for one-third of global death causes, CVDs. The risk factors of CVDs include animal protein (processed red meat is the most obvious) consumption, high serum cholesterol intake, tobacco smoking and alcohol use. These risk factors show a significant correlation with the development of CVDs, and an inverse link is proved with their reduction and cession. The research then illustrates the plant-based diet, free from animal protein, alcohol and tobacco. With more research results on the benefits of a healthy plant-based diet, there has been a rising number of vegans and vegetarians. However, breaking a decades-long eating habit and developing a healthy one has its barriers. The sensual pleasure of eating meat, concerns about nutritional deficiencies, inconvenience of eating plant-based, and family and social pressure are the hindrances to changing to a proven healthier diet. Although research on healthy and nutritious diets is constantly updated, it takes time and effort for the public to accept and adopt the new diet that can help achieve common well-being.




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