A vegan diet is comprised of plant-based foods. These foods are vegetables, fruits, nuts, grains, and other foods which are strictly derived from plants. A vegan diet does not include foods from animal sources. An individual choice of a vegan diet is based on personal reasons. Some people go vegans for health reasons- low risk for some diseases; others chose to be vegans to protect the environment and to avoid harming the animal. A plant-based diet has real health benefits, but going off animal products completely pose some challenges of lack of certain vital nutrients.
Consequently, a vegan diet has a remarkable impact on health ranging from chronic disease management and control to reduction of risk of some diseases.
Health Impact of Vegans Diet
Vegan’s diet is usually rich in dietary fibre, folic acid, magnesium, iron, photochemical, and vitamins C and E. The diet also tends to be low in saturated fats and cholesterol, calories, omega-3 fatty acids, zinc, calcium, vitamins D and B-12. In general, people who practice a vegan diet enjoy health benefits. For instance, they have a low risk of cardiovascular disease (CVD), diabetes type two, obesity, and low risk of some cancer strains (Radnitz, Beezhold, & DiMatteo, 2015). Plant-based foods have a higher rating in reducing chronic diseases due to the metabolic evidence they imply.
The high intake of fruit and vegetables lowers the risk of cancer growth. Also, the rate of reducing CVD and osteoporosis risk is impressive. Reduced intake of whole grains has been shown to increases risk of colorectal cancer and diabetes type 2; reduced intake of nuts increases the risk of cardiovascular disease (Radnitz et al., 2015). Therefore, the choice of plant-based foods has a positive impact on health that outweighs the negative effects on health.
Effects of Vegan Diet on Cardiovascular Diseases
One area where a vegan diet has implied a significant impact is on reducing cardiovascular diseases. Clinical observations of vegans are that they are thinner; they have lower blood pressure and low-density lipoprotein as compared to other vegetarians (Zarraga, & Schwarz, 2006). A low body mass index (BMI) and low blood lipids are evident in vegans across races and not only in whites. Observing vegans diet will put an individual on a safer side of developing CVD.
CVD happens when there are fatty deposits on the inner walls of the arteries. These fatty deposits restrict blood flow reducing the amount of blood that reaches essential organs such as heart and brains. If the brained is denied enough blood flow an ischaemic stroke can develop, and it can be severe depending on how long the brain is deprived oxygen (Zarraga, & Schwarz, 2006). Vegans diet have low plasma cholesterol, LDL, and observed low mean BMI, which reduces the risk of obesity and lowers the level of blood lipids, significantly reducing heart diseases risks.
Vegans consume large amounts of vegetables and fruits. Fruits and vegetables provide fibre, antioxidants, folic acid, and phytochemicals (Tonstad, Butler, Yan, & Fraser, 2009). Correctively these nutrients result in low blood cholesterol concentration, reduced stroke incidences, the reduced mortality rate from ischaemic heart disease and stroke. Also, the high intake of soy, whole grains and nuts provide cardioprotective effects.
Effects of a Vegan Diet on Cancer
In preventing the development and progression of cancer, vegan diet plays an important role. This is because the vegetarian diet provides vital cancer-protective dietary components. Obesity is one of the risk factors for developing cancer (Tantamango-Bartley, Jaceldo-Siegl, Fan, & Fraser, 2013). The quality of the vegan diet of having low BMI effect helps in the control of obesity, reducing the risk of cancer.
Vegan’s diet is characterized by more legumes, more fruits and vegetables, allium vegetables, tomatoes, vitamin C and fibre than what is found in omnivores. These foods help to fight cancer growth. Fruits and vegetables are effective against lung cancer, cancer of the mouth, oesophagus and to some extent stomach cancer (Tantamango-Bartley et al., 2013). Legumes offer protection against stomach and prostate cancer. Carotenoids, vitamin C, fibres and other plant phytochemicals in the diet have been shown to protect against various cancers. Allium vegetables and garlic protect against stomach cancer and colorectal cancer respectively with tomatoes acting against prostate cancer.
The phytochemicals contained in fruits and vegetables are another big player in cancer management. These phytochemicals have shown to contain potent antiproliferative and antioxidant activity, and also they have additive and synergistic effects (Tonstad et al., 2009). Due to these factors, phytochemicals interfere and controls cellular processes that result in cancer progression. The mechanisms that are involved in cancer progression include blocking cell proliferation, hampering DNA adduct formation, hindering phase 1 enzymes and oncogene expression, lowering cell-cycle-arrest and apoptosis, inhibiting phase 2 enzymes, stopping nuclear factor-Kb formation, and impeding angiogenesis (Tantamango-Bartley et al., 2013). The decreased risk of cancer among vegetarians can be attributed to phytochemicals which bioavailability is much determined by food preparation.
Another detail about vegan’s diet concerning cancer is the aspect of protein avoided and the protein consumed. Red meat is mostly associated with risk of colorectal cancer. The range of risk of esophageal, colorectal, lung and liver cancer is between 20% and 60% for those who consume large quantities of red meat than those who consume less red meat. Also, eggs consumption has been associated with the development of pancreatic cancer. Vegans avoid meat and eggs altogether; instead, they consume more legumes as an alternative protein source. Legumes are associated with reduced risk of prostate cancer and colon cancer. Therefore, the protein source choice of vegans puts them in a favorable position when it comes to cancer development.
Effects of Vegan Diet on Bone Health
Another health field where vegans’ diet has a significant effect is bone health. The evidence shows no difference in bone mineral density (BMD) in trabecular and cortical bones between lacto-ovo-vegetarians and omnivores (Tucker, 2014). But, in Asian women, spine and hip bone mineral density were showed to be low in long-term vegans. A vegan diet has low protein and calcium intake, and this can be attributed to being the cause of hip and spine bone loss and fractures among the elderly.
A vegan generally faces the problem of consuming inadequate calcium. This is because a vegan diet falls short of the recommended daily intake (RDA) for calcium (Tucker, 2014). Although the risk of bone fracture among vegans is the same as that of omnivores, the increased occurrence of bone fractures in vegans is attributed to consumption of insufficient calcium.
In general, bone health depends on other nutrients, not just protein and calcium. Vitamin D, vitamin K, magnesium and potassium from soy and vegetables and fruits affect bone health. A vegan diet provides these crucial elements from an appropriate choice of food. Acid-base balance is significant in maintaining bone health. Since calcium is used as a buffer in extracellular fluid pH, a drop in pH results to bone resorption (Tucker, 2014). A diet rich in fruits and vegetables is a typical vegan diet and has a positive influence on calcium levels which is a critical ingredient in bone metabolism.
Fruits and vegetables are rich in potassium and magnesium. These two minerals create alkaline ash that prevents bone resorption. Intake of potassium in required RDA is associated with greater BMD of the lumbar spine and femoral neck among premenopausal women.
In addition, the intake of soy products increases soy isoflavones which are significant in maintaining bone health by improving BMD. Vegan’s diet provides bone protective factors; therefore, by ensuring there is an adequate intake of calcium bone health is not an issue among vegans.
Shortcomings OG Vegans Diet
To get a nutritionally balanced diet, an individual must know what constitutes such a balanced nutritional diet. Another essential detail to obtain such a diet is the accessibility of foods. These are those foods that are fortified with nutrients that are lacking in a diet to make in nutritionally stable (Pistollato et al., 2015). The accessibility of these fortified foods is dependent on the geographical region a consumer resides since different countries have put in place different fortification laws. Some nutrients are vital to health, and a vegan diet does not provide. The supplemental source of these nutrients is essential to avoid adverse effects on health.
n-3 Polyunsaturated fat
Vegans’ diet strictly does not include any animal or animal products in its composition. That is to mean fish, sea vegetables and eggs which are the source of long-chain n-3 fatty acids, docosahexaenoic acid (DHA; 22:6n-3), and eicosapentaenoic acid (EPA; 20:5n-3) are not included in the diet (Saunders, Davis, & Garg, 2013). These fatty acids are important in maintaining cardiovascular health, eye health and brain functions. Plants have a type of n-3 fatty acid known as α-linoleic acid (ALA; 18:3n-3), this fatty acid can be converted into EPA and DHA though with low efficiency (Saunders et al., 2013). Vegans have a low concentration of EPA and DHA in their blood as compared to other types of diets.
Vegans can find DHA in microalgae supplementation that contains DHA and in DHA fortified foods. The body can get EPA from DHA retro conversion; also brown algae (kelp) are a good source of EPA. The RDA of EPA and DHA are 1.6 ALA/D for men and 1.1 ALA/d for women which is less than 1% of daily calorie intake (Saunders et al., 2013). The regular supply of ALA-rich foods and DHA fortified foods ensure the vegan attain the essential n-3 fatty acids. However, these DHA supplements should be taken in moderation since they can give rise to total cholesterol and LDL cholesterol, although they can lower blood plasma triacylglycerol.
Vitamin D
The vegan diet has a low supply of vitamin D in general. The most inadequate mean intake of vitamin D is 0.88µg/d, for vegans this mean is attained by sun exposure and intake of vitamin D fortified foods (Ho-Pham et al., 2012). In world regions where there is no food fortification with vitamin D, supplementation of vitamin D is essential. Another group of vegans that need supplementation are those that live in high latitudes where the sun in inadequate for months in a year and those who cover their bodies for cultural reasons hampering skin exposure to the sun. Another factor is that vitamin D2, which is the most acceptable form among vegans is less bioavailable than vitamin D3, which is animal-derived.
Iron
There are two types of iron, heme iron and non-heme iron. Heme iron is found in animal sources while non-heme is from plant foods. The absorption of heme iron from animal sources is much higher than that of non-heme iron from plant sources (Craig, 2009). However, the hemoglobin concentration and iron deficiency anaemia risk among vegans, omnivores and other vegetarians are similar. This can be attributed to a large intake of vitamin C among vegans that improves non-heme iron absorption rate. Vegans have low ferritin concentration, same mean values as other vegetarians but low than mean concentration among omnivores.
Vitamin B-12
Vitamin B-12 is another vital nutrient that a vegan diet has a low supply. Vegans have a low concentration of plasma vitamin B-12, they are more at risk of vitamin B-12 deficiency, and they have significantly high plasma homocysteine concentration. Increased homocysteine is a risk factor for osteoporotic bone fracture and CVD (Elmadfa & Singer, 2009). The complications that result from vitamin B-12 deficiency include psychoses, ataxia, paresthesia, dementia, concentration difficulties and mood and motor disturbances. In addition, apathy and delayed milestone is an effect of vitamin B-12 deficiency.
Zinc
A vegan diet is considered inferior in the supply of zinc. Grains, legumes and seeds which make part of vegan’s diet have a component known as phytate. This component binds zinc inhibiting its bioavailability. Although vegans have low zinc intake, they do not show immunocompetence as it is implicated by assessment of cell cytotic activities (Foster, Chu, Petocz, & Samman, 2013). This is imputed to the presence of zinc absorption facilitators that help vegans adapt to insufficient zinc supply.
Dietary Recommendations to Optimize Nutrients in a Vegan diet
To avoid vitamin B-12 deficiency, vegans should regularly consume vitamin B-12 fortified foods. These foods include fortified soy, rice beverages, meat analogs, breakfast cereals, and yeast fortified with vitamin B-12, or they can ensure a daily intake of vitamin B-12 supplements (Craig, 2009). There is no unfortified plant food that contains active vitamin B-12.
To optimize calcium in the diet, foods fortified with calcium should be included regularly in the diet. Calcium-fortified foods include calcium-fortified soy, ready-to-eat cereals, rice beverages and apple and orange fortified juices and beverages (Craig, 2009). Vitamin D is found in most fortified food, and where there is no fortification vitamin D supplement should be taken.
The choice of a vegan diet has a significant impact on the health of an individual. The impact is dependent on the knowledge of appropriate components of a healthy diet, and this influences food choices. Vegan’s diet is very vital in the management and control of chronic diseases. These chronic diseases include diabetes type 2, cardiovascular diseases, bone health, and cancer.
Although a vegan diet provides most of the nutrients the body requires, some nutrients are reduced in supply by avoiding animal sources entirely in the diet. Deficiency of these vital nutrients can result in some negative effect on health, and some of the impacts can be irreversible. The nutrients that are most compromised in the vegan diet include n-3 fatty acids, vitamin B-12, vitamin D, calcium, and zinc. To ensure an adequate supply of these essential nutrients, most plant foods are fortified with them, and regular intake of these fortified foods is paramount to avoid deficiency. In cases where fortified foods are unavailable, supplementation is encouraged.
References
Craig, W. J. (2009). Health effects of vegan diets. The American journal of clinical nutrition, 89(5), 1627S-1633S.
Elmadfa, I., & Singer, I. (2009). Vitamin B-12 and homocysteine status among vegetarians: a global perspective. The American journal of clinical nutrition, 89(5), 1693S-1698S.
Elorinne, A. L., Alfthan, G., Erlund, I., Kivimäki, H., Paju, A., Salminen, I., … & Laakso, J. (2016). Food and nutrient intake and nutritional status of Finnish vegans and non-vegetarians. PLOS one, 11(2), e0148235.
Foster, M., Chu, A., Petocz, P., & Samman, S. (2013). Effect of vegetarian diets on zinc status: a systematic review and meta‐analysis of studies in humans. Journal of the Science of Food and Agriculture, 93(10), 2362-2371.
Ho-Pham, L. T., Vu, B. Q., Lai, T. Q., Nguyen, N. D., & Nguyen, T. V. (2012). Vegetarianism, bone loss, fracture and vitamin D: a longitudinal study in Asian vegans and non-vegans. European journal of clinical nutrition, 66(1), 75-82.
Pistollato, F., Sumalla Cano, S., Elio, I., Masias Vergara, M., Giampieri, F., & Battino, M. (2015). Plant-based and plant-rich diet patterns during gestation: beneficial effects and possible shortcomings. Advances in Nutrition, 6(5), 581-591.
Radnitz, C., Beezhold, B., & DiMatteo, J. (2015). Investigation of lifestyle choices of individuals following a vegan diet for health and ethical reasons. Appetite, 90, 31-36.
Saunders, A. V., Davis, B. C., & Garg, M. L. (2013). Omega‐3 polyunsaturated fatty acids and vegetarian diets. Medical journal of Australia, 199, S22-S26.
Tantamango-Bartley, Y., Jaceldo-Siegl, K., Fan, J., & Fraser, G. (2013). Vegetarian diets and the incidence of cancer in a low-risk population. Cancer Epidemiology and Prevention Biomarkers, 22(2), 286-294.
Tonstad, S., Butler, T., Yan, R., & Fraser, G. E. (2009). Type of vegetarian diet, body weight, and prevalence of type 2 diabetes. Diabetes care, 32(5), 791-796.
Tucker, K. L. (2014). Vegetarian diets and bone status. The American journal of clinical nutrition, 100(suppl_1), 329S-335S.
Zarraga, I. G., & Schwarz, E. R. (2006). Impact of dietary patterns and interventions on cardiovascular health. Circulation, 114(9), 961-973.