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Pulls from Health effects of vegan diets by Winston J Craig

Micronutrients of special concern for the vegan include vitamins B-12 and D, calcium, and long-chain n–3 (omega-3) fatty acids. Unless vegans regularly consume foods that are fortified with these nutrients, appropriate supplements should be consumed. In some cases, iron and zinc status of vegans may also be of concern because of the limited bioavailability of these minerals.

Vegan diets are usually higher in dietary fiber, magnesium, folic acid, vitamins C and E, iron, and phytochemicals, and they tend to be lower in calories, saturated fat and cholesterol, long-chain n–3 (omega-3) fatty acids, vitamin D, calcium, zinc, and vitamin B-12 (8). In general, vegetarians typically enjoy a lower risk of cardiovascular disease (CVD), obesity, type 2 diabetes, and some cancers (3).

In summarizing the published research, Fraser (11) noted that, compared with other vegetarians, vegans are thinner, have lower total and LDL cholesterol, and modestly lower blood pressure.

A higher consumption of fruit and vegetables, which are rich in fiber, folic acid, antioxidants, and phytochemicals, is associated with lower blood cholesterol concentrations (17), a lower incidence of stroke, and a lower risk of mortality from stroke and ischemic heart disease

Vegans consume considerably more legumes, total fruit and vegetables, tomatoes, allium vegetables, fiber, and vitamin C than do omnivores (14–16, 20, 23). All those foods and nutrients are protective against cancer (25). Fruit and vegetables are described as protective against cancer of the lung, mouth, esophagus, and stomach and to a lesser degree some other sites, whereas the regular use of legumes provides a measure of protection against stomach and prostate cancer.

Red meat and processed meat consumption are consistently associated with an increase risk of colorectal cancer (). Those in the highest quintile of red meat intake had elevated risks, ranging from 20% to 60%, of esophageal, liver, colorectal, and lung cancers than did those in the lowest quintile of red meat intake (). In addition, the use of eggs was recently shown to be associated with a higher risk of pancreatic cancer

Data from the Adventist Health Study showed that consumption of soy milk by vegetarians protected them against prostate cancer (), whereas in other studies the use of dairy was associated with an increased risk of prostate cancer

To date, epidemiologic studies have not provided convincing evidence that a vegan diet provides significant protection against cancer.

Bone health depends on more than just protein and calcium intakes. Research has shown that bone health is also influenced by nutrients such as vitamin D, vitamin K, potassium, and magnesium and by foods such as soy and fruit and vegetables

Risk of hip fracture was decreased 45% for ≥1 servings/d of green leafy vegetables (the main vitamin K source) compared with ≤1 serving/wk (). In the Framingham Heart Study, elderly men and women in the highest quartile of vitamin K intake had a 65% decreased risk of hip fracture than did those in the lowest quartile

Diets that do not include fish, eggs, or sea vegetables (seaweeds) generally lack the long-chain n–3 fatty acids, eicosapentaenoic acid (EPA; 20:5n−3) and docosahexaenoic acid (DHA; 22:6n−3), which are important for cardiovascular health as well as eye and brain functions

Vegans should be able to easily reach the n–3 fatty acid requirements by including regular supplies of ALA-rich foods in their diet and also DHA-fortified foods and supplements

Compared with lactoovovegetarians and omnivores, vegans typically have lower plasma vitamin B-12 concentrations, higher prevalence of vitamin B-12 deficiency, and higher concentrations of plasma homocysteine

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Updated 10 months ago

Pulls from HEALTH BENEFITS AND RISK ASSOCIATED WITH ADOPTING A VEGETARIAN DIET by Wiesław Pilis, Krzysztof Stec1, Michał Zych, Anna Pilis

The potential effectiveness of vegetarian diets for dealing with obesity was observed in a study by Ton- stad et al. [34] conducted on a group of 22,434 men and 38,469 women where BMI was measured in six treatment groups (vegetarians, vegans, lacto-ovo-vege- tarians, semi-vegetarians, fish eaters, and meat eaters). The mean BMI was found lowest in the vegans (23.06 kg/m2) and gradually increased as follows, lacto-ovo- -vegetarians (25.7 kg/m2), fish eaters (26.3 kg/m2), semi- -vegetarians (27.3 kg/m2) and meat eaters (28.8 kg/m2, p<0.001).

Vegans also showed significant differences to meat eaters (i.e. controls) by having lower blood levels of leukocytes (p<0.05), neutrocytes (statistically insignificant), platelets (p<0.05) and urea (p<0.05) but a higher concentration of albumin (p<0.05). These values may indicate a lower content of protein in the vegetarian diet. In addition, vegetarians run the risk of having a deficiency of iron, calcium, zinc, vitamin D, and B12, as well as of amino acids.

Eating large amounts of vegetables and fruits, which form a major part of all vegetarian diet types, also has a beneficial effect on the cardiovascular system. Plant based foodstuffs (e.g. apples, onions, broccoli, berries, olives, lettuce, tomato, red pepper, grapefruit etc.) provi- de the body with multiple antioxidants. The most active of these include the antioxidant vitamins (α-tocopherol, ascorbic acid), flavonoids and carotenoids (lycopene, lutein, β-carotene, cryptoxanthin, zeaxanthin). Their biological activity are based on inhibiting the oxidation of LDL cholesterol, increasing HDL cholesterol and re-ducing total cholesterol concentrations in the circulation.

A study by Somannavar and Kodliwadmath [29] confirms that vegetarians have significantly higher antioxidant levels compared to those eating a mixed diet (p<0.001). Another health benefit for adopting a vegetarian diet is that blood levels of total cholesterol (T-C) and LDL cholesterol (LDL-C) are maintained correctly. The plasma lipid profiles of vegetarians and those eating a traditional diet was studied by Dourado et al [11] which demonstrated that the latter group had significantly higher average T-C (207.11 mg/dl) and LDL-C (143.79 mg/dl) blood concentrations compared to the former at respectively T-C; 160.06 mg/dl, LDL-C; 87.40 mg/dl (p<0.001). Both of the last aforementioned studies also show that meat eaters have a significantly higher systolic blood pressure (123.76 mmHg) compa- red to vegetarians (114.86 mmHg) (p<0.05).

The authors take the view that the high amounts of carbohydrates and low amounts of fat as seen in vegetarian diets increases cellular insulin sensitivity thereby affording some protection against diabetes. This hypothesis was checked in a study by Tonstad et al [34] conducted on a group of 38,469 women and 22,434 men. It was found that the incidence of type 2 diabetes occurred in the following groups in descending order of magnitude; meat eaters (7.6%), semi-vegetarians (6.1%), fish eaters (4.8%), lacto-ovo-vegetarians (3.2 %) and vegans (2.9%), (p<0.05).

As reported by Borrine et al [7], the body’s need for protein is associated with being provided with adequate amounts of carbohydrates. The body consumes up to twice as much protein du- ring intense exertion when insufficiently supplied with carbohydrates. A high carbohydrate intake beneficially affects muscles and regulates the level of glycogen. … Barr et al. [3] confirmed that the high proportion of carbohydrates in the diet is associated with obtaining better results for endurance sports.

Based on research conducted by the American Dietetic Association and Dieticians of Canada [1], iron intake successively increases for each of the following groups; vegans, lacto-ovo-vegetarians and meat eaters. … A loss of iron in athletes is demonstrated by gastrointestinal bleeding, increased sweating, haemo- lysis and menstrual disorders in women. In most cases, vegetarian athletes can adjust the level of iron by eating foods rich in vitamin C, citric acid, malic acid, tartaric acid, fructose and sorbitol.

Burke et al. [8] have stated that the administering creatinine as a dietary supplement can significantly (p<0.05) increase the physical per- formance and muscle strength of athletes that follow a vegetarian diet.

1. Properly balanced vegetarian diet leads to a lower body mass and lower BMI, compared to meat eaters. There have been attempts to use a vegetarian diet for treating obesity and overweight.
2. A higher intake of carbohydrates achieved through a vegetarian diet may be beneficial for the body by decreasing amounts of saturated fatty acids; this also results in the maintenance of lipid metabolism and lower blood pressure and reduces the incidence of arteriosclerosis, coronary heart disease, type 2 diabetes and metabolic syndrome.
3. Improperly applied vegetarian diets can lead to lo-wered levels of vitamin B12, producing an increase in blood levels of homocysteine, which is associated with increased risk of cardiovascular morbidity, a reduction in the blood levels of sex hormones and disruption of the menstrual cycle.
4. Controversies however remain concerning the safety of a vegetarian diet when adopted by athletes. The concerns relate to a sufficient supply of proteins, iron and creatinine together with the occurrence of irre-gular menstrual cycles, especially in hard-training women. However, some research has demonstrated that a properly balanced vegetarian diet can reduce the adverse symptoms and that such a diet can be successfully used by top level world-class athletes.

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