Unintended Consequences: Nutritional Impact and Potential Pitfalls of Switching from Animal- to Plant-Based Foods

Consumers are shifting towards plant-based diets, driven by both environmental and health reasons. This has led to the development of new plant-based meat alternatives (PBMAs) that are marketed as being sustainable and good for health. However, it remains unclear whether these novel PBMAs to replace animal foods carry the same established nutritional benefits as traditional plant-based diets based on pulses, legumes and vegetables. We modelled a reference omnivore diet using NHANES 2017–2018 data and compared it to diets that substituted animal products in the reference diet with either traditional or novel plant-based foods to create flexitarian, vegetarian and vegan diets matched for calories and macronutrients. With the exception of the traditional vegan diet, all diets with traditional plant-based substitutes met daily requirements for calcium, potassium, magnesium, phosphorus, zinc, iron and Vitamin B12 and were lower in saturated fat, sodium and sugar than the reference diet. Diets based on novel plant-based substitutes were below daily requirements for calcium, potassium, magnesium, zinc and Vitamin B12 and exceeded the reference diet for saturated fat, sodium and sugar. Much of the recent focus has been on protein quality and quantity, but our case study highlights the risk of unintentionally increasing undesirable nutrients while reducing the overall nutrient density of the diet when less healthy plant-based substitutes are selected. Opportunities exist for PBMA producers to enhance the nutrient profile and diversify the format of future plant-based foods that are marketed as healthy, sustainable alternatives to animal-based products.     

Position of the American Dietetic Association and Dietitians of Canada: Vegetarian diets

It is the position of the American Dietetic Association and Dietitians of Canada that appropriately planned vegetarian diets are healthful, nutritionally adequate, and provide health benefits in the prevention and treatment of certain diseases. Approximately 2.5% of adults in the United States and 4% of adults in Canada follow vegetarian diets. A vegetarian diet is defined as one that does not include meat, fish, or fowl. Interest in vegetarianism appears to be increasing, with many restaurants and college foodservices offering vegetarian meals routinely. Substantial growth in sales of foods attractive to vegetarians has occurred, and these foods appear in many supermarkets. This position paper reviews the current scientific data related to key nutrients for vegetarians, including protein, iron, zinc, calcium, vitamin D, riboflavin, vitamin B-12, vitamin A, n-3 fatty acids, and iodine. A vegetarian, including vegan, diet can meet current recommendations for all of these nutrients. In some cases, use of fortified foods or supplements can be helpful in meeting recommendations for individual nutrients. Well-planned vegan and other types of vegetarian diets are appropriate for all stages of the life cycle, including during pregnancy, lactation, infancy, childhood, and adolescence. Vegetarian diets offer a number of nutritional benefits, including lower levels of saturated fat, cholesterol, and animal protein as well as higher levels of carbohydrates, fiber, magnesium, potassium, folate, and antioxidants such as vitamins C and E and phytochemicals. Vegetarians have been reported to have lower body mass indices than nonvegetarians, as well as lower rates of death from ischemic heart disease; vegetarians also show lower blood cholesterol levels; lower blood pressure; and lower rates of hypertension, type 2 diabetes, and prostate and colon cancer. Although a number of federally funded and institutional feeding programs can accommodate vegetarians, few have foods suitable for vegans at this time. Because of the variability of dietary practices among vegetarians, individual assessment of dietary intakes of vegetarians is required. Dietetics professionals have a responsibility to support and encourage those who express an interest in consuming a vegetarian diet. They can play key roles in educating vegetarian clients about food sources of specific nutrients, food purchase and preparation, and any dietary modifications that may be necessary to meet individual needs. Menu planning for vegetarians can be simplified by use of a food guide that specifies food groups and serving sizes. J Am Diet Assoc. 2003;103:748-765.     

Nutrient Intake and Status of German Children and Adolescents Consuming Vegetarian,Vegan or Omnivore Diets: Results of the VeChi Youth Study

There is a lack of data on associations between modern vegetarian and vegan diets and health among children and adolescents. The aim of the Vechi Youth Study was to cross-sectionally examine anthropometry, dietary intakes and nutritional status in a sample of 149 vegetarian, 115 vegan and 137 omnivore children and adolescents (6–18 years old, mean age: 12.7 ± 3.9 years). Group differences of dietary intake (calculated from three-day dietary records), nutrient biomarker and blood lipid concentrations were assessed using an analysis of covariance, adjusted for sex, age and other covariates. The total energy intake did not differ significantly between groups, but intake of carbohydrates was higher among vegetarians and vegans than among omnivores (p = 0.0002, respectively). The median protein intake exceeded 0.9 g/kg body weight/day in all diet groups and was lowest among vegetarians (p < 0.02). There was no significant difference of haemoglobin, vitamin B2, 25-OH vitamin D3, HDL-C and triglycerides blood concentrations between diet groups. Vegan participants had higher folate concentrations than vegetarian participants (p = 0.0053). Ferritin concentration was significantly higher in omnivores than in vegetarians (p = 0.0134) and vegans (p = 0.0404). Vegetarians had lower concentrations of holotranscobalamin (p = 0.0042) and higher concentrations of methylmalonic acid (p = 0.0253) than omnivores. Vegans had the lowest non-HDL-C and LDL-C concentrations in comparison to vegetarians (p = 0.0053 and p = 0.0041) and omnivores (p = 0.0010 and p = 0.0010). A high prevalence (>30%) of 25-OH vitamin D3 and vitamin B2 concentrations below reference values were found irrespective of the diet group. In conclusion, the Vechi Youth Study did not indicate specific nutritional risks among vegetarian and vegan children and adolescents compared to omnivores.     

Vegetarian diets of breastfeeding women in the light of dietary recommendations

The literature review concerning selected nutritional and health aspects of applying different vegetarian diets by breastfeeding women was presented. The only two types of vegetarian diets: lactoovo- and semi-vegetarian, when properly composed, seem to be relatively safe for mother and her child. The most threatening vegetarian diets for lactating women are those including exclusively products of plant origin (so called restricted diets: vegan or macrobiotic). The results of studies performed on mothers consuming these vegetarian diets showed deficiencies in: vitamin B12 and vitamin D (in mothers and their infants) and calcium (only in lactating women). The low intake of docosahexaenoic acid (DHA) was also characteristic in this group. Additionally the endogenous metabolism of DHA is inhibited due to high proportion of linoleic vs. linolenic acid intake. It considered that lactating women on vegetarian diet should have a greater nutritional knowledge in order to avoid deficiencies which would adversely affect mother's and her child's health.     

Nutrient status and growth in vegan children

Vegan diets have risen in popularity over the past 9 years. However, few studies have examined nutrient status and the effect of a vegan diet on the growth of children. This study analysed the existing literature on the health impact and growth impact of selected nutrients in vegan children. We assessed the intake of calories and protein, as well as the nutrients iron, calcium, vitamin D, cobalamin and folate. With a small percentage of outliers, vegan children showed normal growth and were less often obese. We found limited evidence that children on a vegan diet can obtain all the examined nutrients. Furthermore, as proper planning and supplementation by caregivers is needed, it is currently unknown how often vegan children follow well-planned diets. Deficiencies in cobalamin, calcium, and vitamin D seem to be the biggest risks associated with a poorly planned vegan diet. For a more definitive assessment, data on the intake and nutrient status of omega-3 fatty acids, zinc, iodine, and selenium in vegan children are needed. Future research should account for demographic shifts in those following a vegan diet, and should discriminate between vegan sub-populations that are open or closed towards scientific approaches, towards health in general, and toward supplementation. Studies should assess the modes and dosages of supplementation and the use of fortified foods or drinks, as well as adherence to the diet itself. Plant ferritin as a source of iron and endogenous cobalamin synthesis warrants further scientific inquiry. In summary, the current literature suggests that a well-planned vegan diet using supplementation is likely to provide the recommended amounts of critical nutrients to provide for normal progression of height and weight in children, and can be beneficial in some aspects. However, data on 5 critical nutrients are still missing, hampering a more definitive conclusion.     

Placing a Well-Designed Vegan Diet for Slovenes

Interest in vegan diets has increased globally as well as in Slovenia. The quantity of new scientific data requires a thorough synthesis of new findings and considerations about the current reserved position of the vegan diet in Slovenia. There is frequently confusion about the benefits of vegetarian diets that are often uncritically passed on to vegan diets and vice versa. This narrative review aims to serve as a framework for a well-designed vegan diet. We present advice on how to maximize the benefits and minimize the risks associated with the vegan diet and lifestyle. We highlight the proper terminology, present the health effects of a vegan diet and emphasize the nutrients of concern. In addition, we provide guidance for implementing a well-designed vegan diet in daily life. We conducted a PubMed search, up to November 2021, for studies on key nutrients (proteins, vitamin B₁₂, vitamin D, omega-3 long chain polyunsaturated fatty acids (eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)), calcium, iron, zinc, iodine and selenium) in vegan diets. Given the limited amount of scientific evidence, we focus primarily on the general adult population. A well-designed vegan diet that includes a wide variety of plant foods and supplementation of vitamin B₁₂, vitamin D in the winter months and potentially EPA/DHA is safe and nutritionally adequate. It has the potential to maintain and/or to improve health. For physically active adult populations, athletes or individuals with fast-paced lifestyles, there is room for further appropriate supplementation of a conventional vegan diet according to individuals’ health status, needs and goals without compromising their health. A healthy vegan lifestyle, as included in government guidelines for a healthy lifestyle, includes regular physical activity, avoidance of smoking, restriction of alcohol and appropriate sleep hygiene.     

Vegetarian and vegan diets in type 2 diabetes management

Vegetarian and vegan diets offer significant benefits for diabetes management. In observational studies, individuals following vegetarian diets are about half as likely to develop diabetes, compared with non-vegetarians. In clinical trials in individuals with type 2 diabetes, low-fat vegan diets improve glycemic control to a greater extent than conventional diabetes diets. Although this effect is primarily attributable to greater weight loss, evidence also suggests that reduced intake of saturated fats and high-glycemic-index foods, increased intake of dietary fiber and vegetable protein, reduced intramyocellular lipid concentrations, and decreased iron stores mediate the influence of plant-based diets on glycemia. Vegetarian and vegan diets also improve plasma lipid concentrations and have been shown to reverse atherosclerosis progression. In clinical studies, the reported acceptability of vegetarian and vegan diets is comparable to other therapeutic regimens. The presently available literature indicates that vegetarian and vegan diets present potential advantages for the management of type 2 diabetes.     

Non-Pharmacological Treatments for Insulin Resistance: Effective Intervention of Plant-Based Diets—A Critical Review

Plant-based diets are becoming increasingly popular. Vegetarian diets are better for the environment and exhibit health benefits. A correctly balanced plant-based diet is appropriate at every stage of life. Compared to omnivores, vegetarians consume more fruits and vegetables, more fibre, vitamins C and E, magnesium and less saturated fats. In general, they have better nutrition knowledge, and they are slimmer, healthier and live longer than omnivores. It also seems that following a plant-based diet prevents the onset of chronic diseases such as cardiovascular diseases, hypertension, type 2 diabetes, obesity and some cancers. Food intake has a key influence on insulin resistance. Consumption of calorie-rich and highly processed foods, meats and sweetened beverages is a characteristic element of Western diets. They promote and elevate insulin resistance and type 2 diabetes. In contrast, intake of pulses and exclusion of meats as well as animal products bring significant benefits to vegetarian diets. According to studies, vegetarians and vegans have better blood parameters, including better glucose, insulin, total cholesterol, and LDL cholesterol levels. Their homeostatic model assessment for insulin resistance (HOMA-IR) test results are also better. More plant-based foods and fewer animal foods in a diet result in lower insulin resistance and a lower risk of prediabetes and type 2 diabetes. The aim of the study was to investigate the effect of plant-based diets on insulin resistance. In this review, we focused on presenting the positive effects of vegetarian and vegan diets on insulin resistance while showing possible clinical applications of plant-based diets in the treatment and prevention of modern-age diseases. Current and reliable publications meeting the requirements of Evidence-Based Medicine (EBM) were taken into account in this review.     

The effect of diet on plasma homocysteine concentrations in healthy male subjects

OBJECTIVE: To determine the effect of habitual omnivorous and vegetarian diets on folate and vitamin B12 status and the subsequent effect on homocysteine concentration. DESIGN: Cross-sectional comparison of free-living habitual meat-eaters and habitual vegetarians. SETTING: The study was conducted at RMIT University, Melbourne. SUBJECTS: One hundred and thirty-nine healthy male subjects (vegans n=18, ovolacto vegetarians n=43, moderate meat-eaters n=60 and high meat-eaters n=18) aged 20-55 y who were recruited in Melbourne. OUTCOME MEASURES: Fasting plasma or serum from each subject was analysed for folate, vitamin B12 and homocysteine concentration. A semi-quantitative Food Frequency Questionnaire was completed by a subset of subjects from each group to determine methionine intake. RESULTS: The two meat eating groups consumed significantly greater levels of methionine (P<0.001). There was no clear trend in plasma folate status between groups, however the plasma vitamin B12 concentration decreased progressively from the high-meat-eating group to vegans (P<0.05). An inverse trend was observed with plasma homocysteine concentration, with vegans showing the highest levels and high meat eaters the lowest (P<0.05). CONCLUSIONS: Dietary methionine intake has no observable effect on plasma homocysteine concentration. In habitual diets, where folate intake is adequate, lowered vitamin B12 intake from animal foods leads to depleted plasma vitamin B12 concentration with a concomitant increase in homocysteine concentration. The suggested mechanism is the failure to transfer a methyl group from methyl tetrahydrofolate by vitamin B12 in the remethylation of homocysteine to methionine.     

The growth and development of vegan children

The results of prospective study on the growth and diets, estimated from 7-day weighed food intake records, of 20 life vegan children (aged 5.8–12.8 years) are presented. The growth and development of the children were normal but they tended to be lighter in weight and exceptionally lean compared with standards. Heights were around the median of the Tanner-Whitehouse standards but were lower than the medians recently proposed by the Department of Health. Energy intakes were similar to those reported in children of the same age in the general population, but dietary fibre intakes were very high which may have influenced the digestible energy. Sugar provided an average 15.6% of the dietary energy and this was supplied mainly by fruit and fruit juice. Mean fat intakes were close to the dietary reference values. Daily intakes of essential nutrients generally met the amounts recommended, with the exceptions of calcium and vitamin B₁₂. Many children received supplementary sources of vitamin B₁₂ and only two children had intakes below the lower recommended nutrient intake. Intakes of saturated fatty acids were low and those of linoleic acid were high. The ratio of linoleic/α-linolenic acid was high. As docosahexaenoic acid is absent from vegan diets, it is suggested that vegans should use oils with a lower ratio of linoleic/α-linolenic acid. Future studies should also consider the influence of a vegan diet on retinal function. None of the children was immunized against whooping cough and 11 had not been immunized against polio: 16 of the children had suffered from whooping cough. Future studies need to take into account factors other than diet when assessing the health of vegans. The results of this study show that children can be successfully reared on a vegan diet providing sufficient care is taken to avoid the known pitfalls of a bulky diet and vitamin B₁₂ deficiency.     

Changes in nutrient intake and dietary quality among participants with type 2 diabetes following a low-fat vegan diet or a conventional diabetes diet for 22 weeks

BACKGROUND: Although vegan diets improve diabetes management, little is known about the nutrient profiles or diet quality of individuals with type 2 diabetes who adopt a vegan diet. OBJECTIVE: To assess the changes in nutrient intake and dietary quality among participants following a low-fat vegan diet or the 2003 American Diabetes Association dietary recommendations. DESIGN: A 22-week randomized, controlled clinical trial examining changes in nutrient intake and diet quality. SUBJECTS/SETTING: Participants with type 2 diabetes (n=99) in a free-living setting. RESEARCH DESIGN AND METHODS: Participants were randomly assigned to a low-fat vegan diet or a 2003 American Diabetes Association recommended diet. MAIN OUTCOME MEASURES: Nutrient intake and Alternate Healthy Eating Index (AHEI) scores were collected at baseline and 22 weeks. STATISTICAL ANALYSES PERFORMED: Between-group t tests were calculated for changes between groups and paired comparison t tests were calculated for changes within-group. Pearson's correlation assessed relationship of AHEI score to hemoglobin A1c and body weight changes. RESULTS: Both groups reported significant decreases in energy, protein, fat, cholesterol, vitamin D, selenium, and sodium intakes. The vegan group also significantly reduced reported intakes of vitamin B-12 and calcium, and significantly increased carbohydrate, fiber, total vitamin A activity, beta carotene, vitamins K and C, folate, magnesium, and potassium. The American Diabetes Association recommended diet group also reported significant decreases in carbohydrate and iron, but reported no significant increases. The vegan group significantly improved its AHEI score (P<0.0001), while the American Diabetes Association recommended diet group did not (P=0.7218). The difference in AHEI score at 22 weeks between groups was significant (P<0.0001). With both groups combined, AHEI score was negatively correlated with both changes in hemoglobin A1c value (r=-0.24, P=0.016) and weight (r=-0.27, P=0.007). CONCLUSIONS: Vegan diets increase intakes of carbohydrate, fiber, and several micronutrients, in contrast with the American Diabetes Association recommended diet. The vegan group improved its AHEI score whereas the American Diabetes Association recommended diet group's AHEI score remained unchanged.     

Mineral and trace element content of vegetarian diets

Lacto-ovo, lacto, and vegan vegetarian diets were analyzed for calcium, phosphorus, magnesium, zinc, iron, and nitrogen at four calorie intake levels ranging from 1,700 to 2,800 kcal/day. Diets containing dairy products had a high calcium and phosphorus content, ranging from 1,279 to 1,755 mg calcium and 1,378 to 2,160 mg phosphorus for the four calorie levels, respectively, and vegan diets contained less calcium, ranging from 612 to 810 mg. The magnesium content of all three types of vegetarian diets was adequate or high, ranging from 366 to 560 mg/day. The zinc content was lower than that of the RDA (15 mg/day), and was particularly low at the 1,700 calorie intake levels of all diets. The iron content of these diets varied widely and ranged from 12.7 to 22.7 mg. This study has shown that vegetarian diets planned and presented at the higher calorie intake levels contain adequate amounts of minerals and trace elements, whereas this is not the case at the 1,700 calorie intake level. This observation is of importance as the mineral and trace element content of relatively low calorie vegetarian diets would not supply sufficient amounts of these nutrients. In addition, the bioavailability of minerals and trace elements from these diets remains to be determined.     

Vegetarian diets: what are the advantages?

A growing body of scientific evidence indicates that wholesome vegetarian diets offer distinct advantages compared to diets containing meat and other foods of animal origin. The benefits arise from lower intakes of saturated fat, cholesterol and animal protein as well as higher intakes of complex carbohydrates, dietary fiber, magnesium, folic acid, vitamin C and E, carotenoids and other phytochemicals. Since vegetarians consume widely divergent diets, a differentiation between various types of vegetarian diets is necessary. Indeed, many contradictions and misunderstandings concerning vegetarianism are due to scientific data from studies without this differentiation. In the past, vegetarian diets have been described as being deficient in several nutrients including protein, iron, zinc, calcium, vitamin B12 and A, n-3 fatty acids and iodine. Numerous studies have demonstrated that the observed deficiencies are usually due to poor meal planning. Well-balanced vegetarian diets are appropriate for all stages of the life cycle, including children, adolescents, pregnant and lactating women, the elderly and competitive athletes. In most cases, vegetarian diets are beneficial in the prevention and treatment of certain diseases, such as cardiovascular disease, hypertension, diabetes, cancer, osteoporosis, renal disease and dementia, as well as diverticular disease, gallstones and rheumatoid arthritis. The reasons for choosing a vegetarian diet often go beyond health and well-being and include among others economical, ecological and social concerns. The influences of these aspects of vegetarian diets are the subject of the new field of nutritional ecology that is concerned with sustainable life styles and human development.     

The potential of diet to alter disease processes

Diet is a strong factor in the control of atherosclerosis relating to general vascular disease, coronary heart disease and stroke. The interrelated disorders in atherosclerosis of hyperinsulinemia, hyperlipidemia and hypertension are strongly subject to dietary influence. The type of dietary protein, animal versus plant, appears to be as important as the type of lipid, animal versus plant, in atherosclerosis. Dietary protein type, with its differing amino acid ratios, appears to be a major secretagogue of insulin.

Diabetes mellitus, or Type II, diabetes is a related disease where diet is a possible causal or at least a strong contributing factor. Diet is the beginning and continuing basis for the control of Type II diabetes. Interestingly, diabetics have a high incidence of atherosclerosis.

Renal failure has a long history of treatment with protein-restricted diets. Dietary plant protein is a possible therapy mechanism for the treatment of chronic and acute renal failure.

Patients with rheumatic arthritis appear to be helped by specialized dietary approaches. A few examples of the use of vegetarian diets look very promising. Individual arthritic sensitivities or reactivities to certain foods appear to warrant more study.

Osteoporosis is a disease or metabolic disturbance, particularly in postmenopausal women, that shows a need for very high dietary calcium intake. High calcium requirements appear to be related to the very high protein intake of the modern Western diet. A decreased protein intake, as can be obtained on a total vegetarian (vegan) diet, can allow for calcium balance, in a variety of age groups, from one-third to one-fifth the amount of daily calcium required on the Western diet.

Cancer of the breast, colon and prostate appears to have a strong dietary relationship. The incidence of cancer is significantly greater on the modern Western diet than on a vegetarian or vegan diet. The greater antioxidant vitamin content, higher fiber level, higher complex carbohydrate, more unsaturated and less saturated fat, along with a variety of anticancer like compounds in vegetables, grains, legumes, nuts, and fruits are all dietary factors that appear to reduce the risk of cancer.     

Long-chain n-3 polyunsaturated fatty acids in plasma in British meat-eating, vegetarian, and vegan men

BACKGROUND: Plasma concentrations of long-chain n-3 polyunsaturated fatty acids are lower in vegetarians and in vegans than in omnivores. No data are available on whether these concentrations differ between long- and short-term vegetarians and vegans. OBJECTIVES: We compared plasma fatty acid composition in meat-eaters, vegetarians, and vegans and examined whether the proportions of eicosapentaenoic acid (20:5n-3; EPA), docosapentaenoic acid (22:5n-3; DPA), and docosahexaenoic acid (22:6n-3; DHA) were related to the subjects' duration of adherence to their diets or to the proportions of plasma linoleic acid (18:2n-6; LA) and alpha-linolenic acid (18:3n-3; ALA). DESIGN: The present cross-sectional study included 196 meat-eating, 231 vegetarian, and 232 vegan men in the United Kingdom. Information on anthropometry, diet, and smoking habits was obtained through a questionnaire. Total fatty acid composition in plasma was measured. RESULTS: The proportions of plasma EPA and DHA were lower in the vegetarians and in the vegans than in the meat-eaters, whereas only small differences were seen for DPA. Plasma EPA, DPA, and DHA proportions were not significantly associated with the duration of time since the subjects became vegetarian or vegan, which ranged from <1 y to >20 y. In the vegetarians and the vegans, plasma DHA was inversely correlated with plasma LA. CONCLUSIONS: The proportions of plasma long-chain n-3 fatty acids were not significantly affected by the duration of adherence to a vegetarian or vegan diet. This finding suggests that when animal foods are wholly excluded from the diet, the endogenous production of EPA and DHA results in low but stable plasma concentrations of these fatty acids.     

The Relationship between Modern Fad Diets and Kidney Stone Disease: A Systematic Review of Literature

Objectives: Kidney stone disease (KSD) has a strong association with diet metabolic syndrome. This review aims at exploring the lithogenic risk posed by the current most popular diets. Our approach was to search for the effect of each diet type on the major urinary risk factors, to try to draw conclusions regarding the association of a specific diet type and KSD. Methods: This systematic review searched for the available literature exploring the association between the existing popular fad diets and KSD. Articles in English, French and Spanish were included, without restriction of the search period with the final search done in August 2021. Results: Total number of studies and studies for each diet type was as follows: 22 articles for the low carbohydrate diet, 20 articles for high protein diets, 26 articles for vegetarian and vegan diets. There exists a substantial variability in different low carbohydrate and high protein diets, and considerable overlap between modern popular fad diets. High carbohydrate intake might increase urine uric acid, calcium and oxalate levels. High protein diets increase urine calcium and uric acid and lower urine pH and citrate. Consumption of fruits and vegetables increases the urinary volume and urinary citrate. In vegan diets, sufficient daily calcium intake is important to avoid possible secondary hyperoxaluria. Conclusions: Few studies evaluated the direct relationship between modern fad diets and KSD. In general, the reduction of carbohydrate in the diet, and counterbalancing protein rich diets with sufficient intake of fruits and vegetables, seem to play a protective role against KSD formation. Maintaining sufficient calcium intake in vegan and vegetarian diets is important. Additional research is needed to directly evaluate the link between KSD and each diet type.     

Position of the American Dietetic Association: Vegetarian Diets

It is the position of the American Dietetic Association that appropriately planned vegetarian diets, including total vegetarian or vegan diets, are healthful, nutritionally adequate, and may provide health benefits in the prevention and treatment of certain diseases. Well-planned vegetarian diets are appropriate for individuals during all stages of the life cycle, including pregnancy, lactation, infancy, childhood, and adolescence, and for athletes. A vegetarian diet is defined as one that does not include meat (including fowl) or seafood, or products containing those foods. This article reviews the current data related to key nutrients for vegetarians including protein, n-3 fatty acids, iron, zinc, iodine, calcium, and vitamins D and B-12. A vegetarian diet can meet current recommendations for all of these nutrients. In some cases, supplements or fortified foods can provide useful amounts of important nutrients. An evidence-based review showed that vegetarian diets can be nutritionally adequate in pregnancy and result in positive maternal and infant health outcomes. The results of an evidence-based review showed that a vegetarian diet is associated with a lower risk of death from ischemic heart disease. Vegetarians also appear to have lower low-density lipoprotein cholesterol levels, lower blood pressure, and lower rates of hypertension and type 2 diabetes than nonvegetarians. Furthermore, vegetarians tend to have a lower body mass index and lower overall cancer rates. Features of a vegetarian diet that may reduce risk of chronic disease include lower intakes of saturated fat and cholesterol and higher intakes of fruits, vegetables, whole grains, nuts, soy products, fiber, and phytochemicals. The variability of dietary practices among vegetarians makes individual assessment of dietary adequacy essential. In addition to assessing dietary adequacy, food and nutrition professionals can also play key roles in educating vegetarians about sources of specific nutrients, food purchase and preparation, and dietary modifications to meet their needs.     

The nutritional status of iron, folate, and vitamin B-12 of Buddhist vegetarians

Nutritional status of iron, folate, and vitamin B-12 in vegetarians were assessed and compared with those of non- vegetarians in Korea. The vegetarian subjects were 54 Buddhist nuns who ate no animal source food except for dairy products. The non-vegetarians were divided into two groups: 31 Catholic nuns and 31 female college students. Three-day dietary records were completed, and the blood samples were collected for analyzing a complete blood count, and serum levels of ferritin, folate, and vitamin B-12. There was no difference in hemoglobin among the diet groups. The serum ferritin and hematocrit levels of vegetarians did not differ from that of non- vegetarian students with a high intake of animal source food but low intake of vitamin C, and the levels were lower than that of non-vegetarian Catholic nuns with a modest consumption of animal source food and a high intake of vitamin C. The serum vitamin B-12 levels of all subjects except one vegetarian and the serum folate levels of all subjects except one non-vegetarian student fell within a normal range. In vegetarians, there was a positive correlation between the vitamin C intake and serum ferritin levels as well as between the laver intake and serum vitamin B-12 levels. In order to achieve an optimal iron status, both an adequate amount of iron intake and its bioavailability should be considered. Sufficient intake of vegetables and fruits was reflected in adequate serum folate status. Korean laver can be a good source of vitamin B-12 for vegetarians.     

Long-term effect of a plant-based diet on magnesium status during pregnancy

OBJECTIVE: To compare dietary magnesium intake and magnesium concentrations in serum, red blood cells (RBC) and urine during pregnancy of women habitually following a long-term plant-based diet and of women following an average Western (control) diet. DESIGN: Prospective study during pregnancy. SETTING: Giessen, Germany. SUBJECTS: Healthy pregnant women (n=108) in their 9-12th, 20-22nd and 36-38th gestational week habitually following a plant-based diet for more than 3 y or an average Western diet. The vegetarians were subdivided into ovo-lacto vegetarians (n=27) and low-meat eaters (n=43). RESULTS: Significant higher dietary magnesium intakes were observed in pregnant women consuming a plant-based diet (508+/-14 mg/day for ovo-lacto vegetarians, P<0.001 and 504+/-11 mg/day for low-meat eaters, P<0.001) than in pregnant women consuming a control diet (412+/-9 mg/day). Serum magnesium concentrations were similar in all diet groups whereas RBC magnesium was slightly higher in low-meat eaters than in controls (P=0.058). Urinary magnesium excretion was higher in ovo-lacto vegetarians (P=0.023), followed by low-meat eaters (P=0.017) when compared to the control group. During the third trimester of pregnancy, the frequency and the occurrence of calf cramps was lower in the plant-based diet group than in the control group (P=0.004 and 0.008). CONCLUSIONS: Owing to a higher dietary magnesium intake confirmed by higher urinary magnesium excretion, habitual plant-based diets result in a slightly improved magnesium status during pregnancy and reduce the frequency of calf cramps during the third trimester of pregnancy compared to an average Western diet. Therefore, plant-based diets during pregnancy can be recommended with regard to magnesium supply.