Vegetarians do not consume food and food products from animals – no meat and products made from it, no fish and no animal fats – for ideological, religious, ecological or nutritional reasons, as well as animal welfare considerations; instead, they eat a predominantly plant-based diet. In addition, the food is consumed as naturally as possible. A distinction is made between ovo-lacto-vegetarians, who consume eggs as well as milk and dairy products as animal protein sources, and lacto-vegetarians, who consume only milk and dairy products as animal protein sources in addition to plant foods. Not vegetarians in the strict sense are the so-called pesco-vegetarians, who eat like ovo-lacto-vegetarians and also eat fish and seafood.Vegans are to be distinguished from vegetarians. Vegans eat only plant foods.Ovo-lacto-vegetarians are most common among vegetarians.
Epidemiology
In the 2008 “National Nutrition Survey II,” 1.6% of participants reported being vegetarian. Meanwhile (as of January 2015), the German Vegetarian Union (VEBU) estimates that there are approximately 7.8 million vegetarians and approximately 900,000 vegans (in Germany).
Positive effects
A vegetarian diet usually contains little fat, especially very little animal fat (saturated fat and cholesterol). In contrast, the proportion of fats with monounsaturated and polyunsaturated fatty acids is much higher than is generally the case. The micronutrient supply (vital substances) of ovo-lacto- and lacto-vegetarians is also usually much better because of the high proportion of plant foods. These are probably the main reasons why vegetarians have better laboratory values for total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides and uric acid, a lower body weight and a significantly lower risk of contracting many chronic diseases such as diabetes mellitus, nephropathies (kidney diseases) and myocardial infarctions (heart attacks) compared to a control group eating a standard mixed diet. Because of their high fiber intake, vegetarians rarely suffer from diverticulosis (protrusions of the intestinal wall) and gallstones. In a study of more than 73,000 Adventists – this religious group does not eat pork and abstains from stimulants such as alcohol and tobacco – the mortality rate (death rate) was 12% lower among vegetarians than among meat-eating participants. Men in particular seem to benefit from a vegetarian diet. For them, the mortality rate was 18% lower than for meat eaters. No significant differences were found in women, which is probably due to the fact that women already eat a very healthy diet. This observation is also supported by a Heidelberg study: vegetarians have no advantages over health-conscious non-vegetarians in terms of life expectancy.A vegetarian diet appears to have a particularly positive effect on cardiovascular events such as ischemic heart disease (e.g., angina pectoris (chest tightness), myocardial infarction (heart attack)). A meta-analysis shows a 29% reduction in CHD mortality (mortality from coronary heart disease). The morbidity rate for diabetes mellitus is also lower in men who eat a vegetarian diet. The meta-analysis also showed an 18% lower incidence of cancer (new cancer incidence rate).Vegetarians have a 9% lower all-cause mortality rate compared to non-vegetarians. Pesco vegetarians have the lowest mortality rate. It is 19% lower than for mixed-food eaters, and again the difference was most significant among men (27% lower). In all these results, it must be taken into account that vegetarians in most cases smoke less, drink alcohol less often, exercise more, and have a lower BMI (body mass index; body mass index) than non-vegetarians. These factors, of course, also influence the study results.
Negative effects
Because dairy and milk products are absent from the diets of ovo-vegetarians, there is a particular risk of calcium deficiency, because more than 50% of calcium is absorbed through the consumption of dairy and milk products. Deficiency symptoms include abdominal pain, diarrhea (diarrhea), and cramps.Suitable vegetarian sources of calcium are fortified soy products, dark green vegetables such as kale, spinach and broccoli, nuts such as almonds and hazelnuts, and calcium-rich mineral waters (calcium content > 150 mg/l). Care should be taken to ensure that vegetables are low in oxalate. Oxalic acid reduces the bioavailability of calcium because it forms insoluble complexes with calcium (calcium oxalates). Particularly high levels of oxalate are found in chard, spinach, rhubarb, beet, cocoa powder and chocolate. The consumption of mineral waters containing calcium is also recommended. Likewise, due to the lack of fish consumption (except Pesco vegetarians), the intake of omega-3 fatty acids in vegetarians is critical. Often an undersupply of iodine can be observed due to the avoidance of fish, which is a very good source of iodine (except for Pesco vegetarians). Iodine is also contained in algae and seaweed products, but sometimes in very high amounts. The German Federal Institute for Risk Assessment (BfR) therefore advises against algae products to prevent iodine oversupply. In any case, vegetarians should use iodized table salt. If iodine, an essential trace element for the formation of thyroid hormones, is lacking in our body, this can lead to listlessness as well as increased cholesterol and blood fat levels. Risk groups, including people with a family history of iodine deficiency goiter, are recommended to take iodine tablets. Covering iron requirements is also problematic because the most important sources of iron – veal, pork, beef and liver – are not consumed. Cereals, whole grain and soy products, corn, rice, nuts and other plant products are poorer sources of iron despite their high iron content, because the utilization of this trace element is reduced by the high phytic acid content in them. Phytic acid or phytates form a non-absorbable complex with iron and consequently inhibit iron absorption. Typical deficiency symptoms are fatigue, pallor and headache. Simultaneous intake of vitamin C or vitamin C-rich foods increases enteric iron absorption (uptake of iron in the intestine) by ascorbic acid attenuating the effect of phytates. The simultaneous supply of ascorbic acid can significantly increase the bioavailability of non-heme plant iron in particular. By reducing Fe3+ (trivalent iron) to Fe2+ (divalent iron), ascorbic acid improves the absorption (uptake) of non-heme iron by a factor of 3-4 and stimulates its incorporation into the iron storage protein ferritin. Clinically relevant iron deficiency is rarely found in ovo-lacto vegetarians despite the low intake of iron with low bioavailability. Utilization of zinc in whole grain products is also hindered by the high phytin content. Insufficient supply is manifested by immune deficiency, loss of appetite, and delayed wound healing, among other symptoms. To increase zinc intake, the same measures as described above for iron are useful. If vegetarians consume most of their food without prior heat treatment, they have an increased risk of allergies. This is because heat destroys the antigenic potency of foods. This is especially true for stone and pome fruits, vegetables such as carrots or celery, and nuts.
Conclusion
As far as the general supply of micronutrients is concerned, although it is usually much better in vegetarians than is generally the case, it is still not optimal. Vegetarians must carefully compose their foods to avoid supply shortages. For children, pregnant women and nursing mothers, an adequate ovo-lacto or lacto-vegetarian diet is problematic. The optimal diet is that of pesco-vegetarians, who eat like ovo-lacto-vegetarians and also eat fish and seafood.
