Claus Leitzmann

The new nutrition science project.

Objective To show that nutrition science, with its application to food and nutrition policy, now needs a new conceptual framework. This will incorporate nutrition in its current definition as principally a biological science, now including nutritional aspects of genomics. It will also create new governing and guiding principles; specify a new definition; and add social and environmental dimensions and domains. Method A narrative review of nutrition science, its successes and achievements, and its dilemmas, paradoxes, shortcomings, dissonances and challenges. Reference is made to 16 associated papers. Equal use is made of continuous text and of boxed texts that extend the review and give salient examples. Results Recent and current interrelated electronic and genomic discoveries and linked sequential demographic, nutritional and epidemiological shifts, in the context of associated and interlinked global social, cultural, environmental, economic, political and other developments, altogether amount to a world in revolution, requiring all disciplines including that of nutrition science to make comparably radical responses. Conclusion Nutrition in principle and practice should be a biological and also an environmental and social science. This new broad integrated structure brings much recent and current progressive work into the centre of nutrition science, and in some ways is a renewal of the period when nutrition science had its greatest impact. It amounts to a map charting well-known and also new worlds. The new nutrition science is concerned with personal and population health, and also with planetary health – the welfare and future of the whole physical and living world of which humans are a part. In this way the discipline will make a greater contribution to the preservation, maintenance, development and sustenance of life on Earth, appropriate for the twenty-first century.

Dietary intakes and lifestyle factors of a vegan population in Germany: results from the German Vegan Study

Objective: Evaluation of dietary intakes and lifestyle factors of German vegans.Design: Cross-sectional study.Settings: Germany.Subjects: Subjects were recruited through journal advertisements. Of 868 volunteers, only 154 participated in all study segments (pre- and main questionnaire, two 9-day food frequency questionnaires, blood sampling) and fulfilled the following study criteria: vegan dietary intake at least 1 year prior to study start, minimum age of 18 y, no pregnancy or childbirth during the last 12 months.Interventions: No interventions.Results: All the 154 subjects had a comparatively low BMI (median 21.2 kg/m2), with an extremely low mean consumption of alcohol (0.77±3.14 g/day) and tobacco (96.8% were nonsmokers). Mean energy intake (total collective: 8.23±2.77 MJ) was higher in strict vegans than in moderate ones. Mean carbohydrate, fat, and protein intakes in proportion to energy (total collective: 57.1:29.7:11.6%) agreed with current recommendations. Recommended intakes for vitamins and minerals were attained through diet, except for calcium (median intake: 81.1% of recommendation), iodine (median: 40.6%), and cobalamin (median: 8.8%). For the male subgroup, the intake of a small amount of food of animal origin improved vitamin and mineral nutrient densities (except for zinc), whereas this was not the case for the female subgroup (except for calcium).Conclusion: In order to reach favourable vitamin and mineral intakes, vegans should consider taking supplements containing riboflavin, cobalamin, calcium, and iodine. Intake of total energy and protein should also be improved.Sponsorship: EDEN Foundation, Bad Soden, Germany; Stoll VITA Foundation, Waldshut-Tiengen, Germany

Nutrition ecology: the contribution of vegetarian diets

Nutrition ecology is an interdisciplinary scientific discipline that encompasses the entire nutrition system, with special consideration of the effects of nutrition on health, the environment, society, and the economy. Nutrition ecology involves all components of the food chain, including production, harvesting, preservation, storage, transport, processing, packaging, trade, distribution, preparation, composition, and consumption of food, as well as disposal of waste materials. Nutrition ecology has numerous origins, some of which go back to antiquity. The introduction of industrialized agriculture and mass animal production gave rise to various negative influences on the environment and health. Food quality is determined in part by the quality of the environment. The environment, in turn, is influenced by food consumption habits. Research shows that vegetarian diets are well suited to protect the environment, to reduce pollution, and to minimize global climate changes. To maximize the ecologic and health benefits of vegetarian diets, food should be regionally produced, seasonally consumed, and organically grown. Vegetarian diets built on these conditions are scientifically based, socially acceptable, economically feasible, culturally desired, sufficiently practicable, and quite sustainable.

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.

Dietary Iron Intake and Iron Status of German Female Vegans: Results of the German Vegan Study

Background: As shown in previous studies vegetarians and especially vegans are at risk for iron deficiency. Our study evaluated the iron status of German female vegans. Methods: In this cross-sectional study, the dietary intakes of 75 vegan women were assessed by two 9-day food frequency questionnaires. The iron status was analyzed on the basis of blood parameters. Results: Mean daily iron intake was higher than recommended by the German Nutrition Society. Still 42% of the female vegans <50 years (young women, YW) had a daily iron intake of <18 mg/day, which is the recommended allowance by the US Food and Nutrition Board. The main dietary sources of iron were vegetables, fruits, cereals and cereal products. Median serum ferritin concentrations were 14 ng/ml for YW and 28 ng/ml for women ≧50 years (old women, OW). In all, 40% (tri-index model (TIM) 20%) of the YW and 12% (TIM 12%) of the OW were considered iron-deficient based on either serum ferritin levels of <12 ng/ml or a TIM. Only 3 women had blood parameters which are defined as iron deficiency anemia. Correlations between serum ferritin levels and dietary factors were not found. Conclusion: Although the mean iron intake was above the recommended level, 40% (TIM 20%) of the YW were considered iron-deficient. It is suggested that especially YM on a vegan diet should have their iron status monitored and should consider taking iron supplements in case of a marginal status.

Vegetarian nutrition: past, present, future

Early human food cultures were plant-based. Major religions such as Hinduism and Buddhism have recommended a vegetarian way of life since their conception. The recorded history of vegetarian nutrition started in the sixth century bc by followers of the Orphic mysteries. The Greek philosopher Pythagoras is considered the father of ethical vegetarianism. The Pythagorean way of life was followed by a number of important personalities and influenced vegetarian nutrition until the 19th century. In Europe, vegetarian nutrition more or less disappeared during the Middle Ages. In the Renaissance era and in the Age of Enlightenment, various personalities practiced vegetarianism. The first vegetarian society was started in England in 1847. The International Vegetarian Society was founded in 1908 and the first vegan society began in 1944. Prominent vegetarians during this time included Sylvester Graham, John Harvey Kellogg, and Maximilian Bircher-Benner. A paradigm shift occurred at the turn of the 21st century. The former prejudices that vegetarianism leads to malnutrition were replaced by scientific evidence showing that vegetarian nutrition reduces the risk of most contemporary diseases. Today, vegetarian nutrition has a growing international following and is increasingly accepted. The main reasons for this trend are health concerns and ethical, ecologic, and social issues. The future of vegetarian nutrition is promising because sustainable nutrition is crucial for the well-being of humankind. An increasing number of people do not want animals to suffer nor do they want climate change; they want to avoid preventable diseases and to secure a livable future for generations to come.

Consequences of a long-term raw food diet on body weight and menstruation: results of a questionnaire survey

Objective: To examine the relationship between the strictness of long-term raw food diets and body weight loss, underweight and amenorrhea. Methods: In a cross-sectional study 216 men and 297 women consuming long-term raw food diets (3.7 years; SE 0.25) of different intensities completed a specially developed questionnaire. Participants were divided into 5 groups according to the amount of raw food in their diet (70–79, 80–89, 90–94, 95–99 and 100%). A multiple linear regression model (n = 513) was used to evaluate the relationship between body weight and the amount of raw food consumed. Odds of underweight were determined by a multinomial logit model. Results: From the beginning of the dietary regimen an average weight loss of 9.9 kg (SE 0.4) for men and 12 kg (SE 0.6) for women was observed. Body mass index (BMI) was below the normal weight range (< 18.5 kg/m2) in 14.7% of male and 25.0% of female subjects and was negatively related to the amount of raw food consumed and the duration of the raw food diet. About 30% of the women under 45 years of age had partial to complete amenorrhea; subjects eating high amounts of raw food (> 90%) were affected more frequently than moderate raw food dieters. Conclusions: The consumption of a raw food diet is associated with a high loss of body weight. Since many raw food dieters exhibited underweight and amenorrhea, a very strict raw food diet cannot be recommended on a long-term basis.

Homocysteine and cobalamin status in German vegans.

OBJECTIVE The study aimed to evaluate the homocysteine and cobalamin status of German vegans and determine whether the intake of very small amounts of foods of animal origin can improve this status. DESIGN AND SETTING Cross-sectional study, Germany. SUBJECTS The dietary and nutritional intakes of 131 vegans (73 women, 58 men; age range: 20.2-82.1 years) were evaluated using a general questionnaire and two food-frequency questionnaires. RESULTS The prevalence of inadequate cobalamin status in volunteers of the German Vegan Study was 28.2%, and that of hyperhomocysteinaemia, 38.1%. Moderate vegans were affected to a lesser extent than were strict vegans. Duration of veganism and cobalamin concentration were inversely correlated (Spearmans r=-0.175, P=0.047). Folate concentration and erythrocyte aspartic acid aminotransferase activity were not correlated with plasma homocysteine concentration, but duration of veganism correlated positively with homocysteine concentration (Spearmans r=0.319, P<0.001). Cobalamin and homocysteine concentrations were inversely correlated (when controlling for duration of veganism; r=-0.602, P<0.001). CONCLUSION Cobalamin status needs to be improved in order to minimise the risk of hyperhomocysteinaemia.

German vegan study : Diet, life-style factors, and cardiovascular risk profile

Background/Aim: Evaluation of cardiovascular risk profile in 154 German vegans. Methods: Cross-sectional study, Germany. Study instruments: 2 FFQ, 2 questionnaires, analyses of fasting venous blood samples. Results: The total study population had a low BMI (mean: 22.3 kg/m2), a moderate blood pressure (mean: 120/75 mm Hg), an extremely low consumption of alcohol (mean: 0.77 g/day) and 96.8% were nonsmokers. Moderate physical activity (PAL) was reported by nearly 50%, whereas 22.7% declared to have a high PAL (>3 h/week). Median triacylglycerol (TG) was 0.81 mmol/l, total cholesterol (TC) was 4.33 mmol/l, HDL was 1.34 mmol/l. The mean TC/HDL-ratio was 3.3. Lipoprotein(a) (Lp(a)) was 8.13 mg/dl, concentrations of >30 mg/dl were prevalent in 25% of the participants. In general, status of folate and pyridoxine were sufficient, while 49.7% showed cobalamin concentrations <150 pmol/l. Plasma homocysteine levels were slightly elevated (median: 12.5 µmol/l). Cobalamin concentration and duration of vegan nutrition were the main determinants of homocysteine in the total study population. Conclusion: Although TC and LDL concentrations were favorable, low HDL and elevated homocysteine and Lp(a) concentrations were unfavorable. Overall, these results confirm the notion that a vegan diet is deficient in vitamin B12, which may have an unfavorable effect on CHD risk.

Dimensions, domains and principles of the new nutrition science

OBJECTIVE Following the agreed principles, definition and dimensions of the new nutrition science, to elaborate its overall guiding principles, to propose some domains of its biological, social and environmental dimensions, and to propose a series of principles to govern and guide these dimensions and domains. This paper, part of The New Nutrition Science project, is initial work in progress towards a comprehensive typology of the science, and is designed to stimulate further work. METHOD A review that takes into account the discussions of the Giessen workshop on the new nutrition science, and in particular the workshop agreement as expressed in The Giessen Declaration. Three outlines of the evolutionary, historical and ecological general principles to guide the new nutrition science are given in boxed texts. The suggested specific principles, taken mostly from 14 associated papers and workshop discussion, are an informal supplement to the Declaration. They are presented as further work in progress, to be developed, revised and agreed at future meetings designed to develop the new nutrition science. CONCLUSION An essential aspect of the theory and the practice of the new nutrition science--in common with any scientific discipline and indeed any ordered human activity--is a specification of its dimensions and their domains, with definitions; and also considered and agreed principles to govern and guide its work.