SUBJECT: AJCN Supplement – Vegetarian Diet Benefits from Nutrition Investigator Roc
A remarkable symposium of wonderful reasons to eat nuts, yogurt, fruits, and vegetables, for both health and our planet!
1. Preface – The Sixth International Congress on Vegetarian Nutrition (ICVN) was held February 2013 at Loma Linda University. Since the last congress in 2008, there has been a steady increase in research and the emergence of new perspectives on vegetarian nutrition. A significant highlight was the updates from 2 of the largest continuing prospective studies on vegetarians: the UK Oxford Vegetarian Study and the Loma Linda University Adventist Health Study 2. The contribution of vegetarian diets in maintaining bone health and preventing macular degeneration and cognitive decline were featured in presentations at this congress. Three primary domains can be considered in the study of plant-based and vegetarian diets: food patterns, foods, and nutrients. We provide an increased awareness of the environmental impact and sustainability of protein food production and the consequences of food choices on climate change.
2. Nuts and berries to save your brain – Daily supplementation of between 6 and 9 mL blueberry juice/kg for 12 wk among older individuals with mild cognitive impairment (n = 9) improved cognitive function, particularly with respect to improved paired-associate learning, word list recall, and reduced depressive symptoms. Greater intakes of blueberries and strawberries were associated with slower rates of cognitive decline in an analytic sample consisting of 16,010 women >70 y of age, as were greater intakes of anthocyanidins and total flavonoids. The inclusion of nuts in the diet is associated with a decreased risk of coronary artery disease, hypertension, gallstones, diabetes, cancer, metabolic syndrome, and visceral obesity. Frequent consumption of berries seems to be associated with improved cardiovascular and cancer outcomes, improved immune function, and decreased recurrence of urinary tract infections; the consumption of nuts and berries is associated with reduction in oxidative damage, inflammation, vascular reactivity, and platelet aggregation, and improvement in immune functions. However, only recently have the effects of nut and berry consumption on the brain, different neural systems, and cognition been studied. There is growing evidence that the synergy and interaction of all of the nutrients and other bioactive components in nuts and berries can have a beneficial effect on the brain and cognition. Regular nut consumption, berry consumption, or both could possibly be used as an adjunctive therapeutic strategy in the treatment and prevention of several neurodegenerative diseases and age-related brain dysfunction. A number of animal and a growing number of human studies show that moderate-duration dietary supplementation with nuts, berry fruit, or both is capable of altering cognitive performance in humans, perhaps forestalling or reversing the effects of neurodegeneration in aging. Table of contents of various berries!
3. Meat, salt, added sugar, and processed foods shorten your life! Although reductionist questions about nutrition are legitimate scientifically, a nutrient focus in the public arena forces the food industry to compete with the use of nutrient statements. Consumers must interpret information that may not be correct or relevant. The theory of food synergy, which postulates that the many constituents of individual foods and dietary patterns act together on health, leads to the idea that dietary policy would be clearer if it focused on foods. To illustrate this method, the food-based A Priori Diet Quality Score was described in the Iowa Women’s Health Study; a substantial total mortality reduction for increasing quartiles of the score was found. The simple food-based rules implied in this a priori score support minimizing meat, salt, added sugar, and heavily processed foods while emphasizing phytochemical-rich foods.
4. Those with cardiovascular risk benefit from plant-derived foods – There was a 41% lower risk of death in those whose provegetarian food pattern was over 40 versus those whose scores were less than 30.
5. Osteoporosis is less common in vegetarians, even less in vegans – Vegetarian diets have been shown to contain lower amounts of calcium, vitamin D, vitamin B-12, protein, and n–3 (ω-3) fatty acids, all of which have important roles in maintaining bone health. At the same time, healthy vegetarian diets tend to contain more of several protective nutrients, including magnesium, potassium, vitamin K, and antioxidant and anti-inflammatory phytonutrients. On balance, there is evidence that vegetarians, and particularly vegans, may be at greater risk of lower BMD and fracture. Attention to potential shortfall nutrients through the careful selection of foods or fortified foods or the use of supplements can help ensure healthy bone status to reduce fracture risk in individuals who adhere to vegetarian diets.
6. Plant lutein and zeaxanthin reduce risk for macular degeneration – Plant-based macular xanthophylls (MXs; lutein and zeaxanthin) and the lutein metabolite meso-zeaxanthin are the major constituents of macular pigment, a compound concentrated in retinal areas that are responsible for fine-feature visual sensation.
7. Vegetarian diet pattern has wonderful health results – Vegetarian dietary patterns were associated with lower body mass index, lower prevalence and incidence of diabetes mellitus, lower prevalence of the metabolic syndrome and its component factors, lower prevalence of hypertension, lower all-cause mortality, and in some instances, lower risk of cancer.
8. A vegetarian diet pattern reduces obesity – This review summarizes 2 key lines of evidence: 1) the emergence of an obesity epidemic in urban and rural India and its contribution to the noncommunicable disease (NCD) in India burden and 2) the role of a “nutrition transition” in decreasing the whole plant food content of diets in India and increasing risk of obesity and NCDs. We then present new epidemiologic evidence from Asian Indians enrolled in the Adventist Health Study 2 that raises the possibility of how specific whole plant foods (eg, nuts) in a vegetarian dietary pattern could potentially prevent obesity and NCDs in a target population of >1 billion persons.
9. Vegetarian diets recommended for weight management – Vegetarian diets should be recommended for weight management; however, care should be taken to optimize food intake to provide adequate intakes of nutrients of concern when energy restriction is used in conjunction with a vegetarian dietary pattern. At any caloric amount, vegetarians should optimize intakes of vitamin B-12, zinc, and protein; and both vegetarians and nonvegetarians need to increase intakes of calcium, magnesium, fiber, and vitamins A, C, and E.
10. Plant diet aids microbiome – Many dietary patterns have been associated with cardiometabolic risk reduction. A commonality between these dietary patterns is the emphasis on plant-based foods. Such diets are high in dietary fiber and fermentable substrate (ie, nondigestible or undigested carbohydrates), which are sources of metabolic fuel for gut microbial fermentation and, in turn, result in end products that may be used by the host (eg, short-chain fatty acids). Examples of dietary components that alter the gut microbial composition include prebiotics and resistant starches.
11. Effect of dietary patterns on cancer risk: stomach cancer [RRs compared with meat eaters: 0.62 in fish eaters and 0.37 in vegetarians, colorectal cancer 0.66 in fish eaters and 1.03 in vegetarians; cancers of the lymphatic and hematopoietic tissue 0.96 in fish eaters and 0.64 in vegetarians; multiple myeloma 0.77 in fish eaters and 0.23 in vegetarians; and all sites combined 0.88 in fish eaters and 0.88 in vegetarians.
12. Red and processed meat, but not dairy, increases colorectal cancer – An association between red and processed meat consumption and colorectal cancer was convincing. In addition, the effect of other animal products on cancer risk has been studied, and the WCRF/AICR report concluded that milk probably decreases the risk of colorectal cancer but diets high in calcium probably increase the risk of prostate cancer. In 2006 the International Agency for Research on Cancer concluded that nitrate and nitrite ingested under conditions that cause endogenous nitrosation are “probable human carcinogens
13. Nuts and yogurt reduce weight gain, chips and fries increase it – Nuts are rich in protein and dietary fiber, which are associated with increased satiety. Several independent prospective studies found that increasing nut consumption was associated with lower weight gain over relatively long periods of time. Regular consumption (approximately one handful daily) of nuts over the long term, as a replacement to less healthful foods, can be incorporated as a component of a healthy diet for the prevention of obesity and type 2 diabetes. See a table of how various foods affect long term weight gain or loss.
14. Nuts reduce apetite – Tree nuts and peanuts are good sources of many nutrients and antioxidants, but they are also energy dense. The latter often limits intake because of concerns about their possible contribution to positive energy balance. However, evidence to date suggests that nuts are not associated with predicted weight gain. This is largely due to their high satiety value, leading to strong compensatory dietary responses, inefficiency in absorption of the energy they contain, a possible increment in resting energy expenditure, and an augmentation of fat oxidation. Preliminary evidence suggests that these properties are especially evident when they are consumed as snacks.
15. Soy intake reduces breast cancer risk – Over the past 2 decades, soy foods have been the subject of a vast amount of research, primarily because they are uniquely rich sources of isoflavones. Isoflavones are classified as both phytoestrogens and selective estrogen receptor modulators. The phytoestrogenic effects of isoflavones have led some to view soy foods and isoflavone supplements as alternatives to conventional hormone therapy. However, clinical research shows that isoflavones and estrogen exert differing effects on a variety of health outcomes. Nevertheless, there is substantial evidence that soy foods have the potential to address several conditions and diseases associated with the menopausal transition. For example, data suggest that soy foods can potentially reduce ischemic heart disease through multiple mechanisms. Soy protein directly lowers blood low-density lipoprotein-cholesterol concentrations, and the soybean is low in saturated fat and a source of both essential fatty acids, the omega-6 fatty acid linoleic acid and the omega-3 fatty acid alpha-linolenic acid. In addition, soflavones improve endothelial function and possibly slow the progression of subclinical atherosclerosis. Isoflavone supplements also consistently alleviate menopausal hot flashes provided they contain sufficient amounts of the predominant soybean isoflavone genistein. In contrast, the evidence that isoflavones reduce bone loss in postmenopausal women is unimpressive. Whether adult soy food intake reduces breast cancer risk is unclear. Considerable evidence suggests that for soy to reduce risk, consumption during childhood and/or adolescence is required. Although concerns have been raised that soy food consumption may be harmful to breast cancer patients, an analysis in 9514 breast cancer survivors who were followed for 7.4 y found that higher postdiagnosis soy intake was associated with a significant 25% reduction in tumor recurrence. In summary, the clinical and epidemiologic data indicate that adding soy foods to the diet can contribute to the health of postmenopausal women.
16. Soy inhibits prostate cancer – Prostate cancer (PCa) is the most commonly diagnosed cancer in men in the United States and the second leading cause of cancer death. The natural product genistein, found in high amounts in soy products, has been implicated in preventing PCa formation and metastasis in men who consume high amounts of soy. In vitro studies and in vivo rodent models that used human PCa cells, as well as prospective human clinical trials, provide a mechanistic explanation directly supporting genistein as an antimetastatic agent. Phase I and phase II clinical trials conducted by us and others showed that concentrations of genistein associated with antimetastatic efficacy in preclinical models are achievable in humans.
17. Soak beans and discard water to reduce gas – Dried beans (often referred to as grain legumes) may contribute to some of the health benefits associated with plant-based diets. Beans are rich in a number of important micronutrients, including potassium, magnesium, folate, iron, and zinc, and are important sources of protein in vegetarian diets. The relatively low bean intakes of North Americans and northern Europeans can be attributed to a negative culinary image as well as to intestinal discomfort attributable to the oligosaccharide content of beans. Cooking practices such as sprouting beans, soaking and discarding soaking water before cooking, and cooking in water with a more alkaline pH can reduce oligosaccharide content.
18. Shorter omega-3s from plants have health benefits – α-Linolenic acid (ALA) is an n–3 (ω-3) fatty acid found mostly in plant foods such as flaxseed, walnuts, and vegetable oils, including canola and soybean oils. Most of the health benefits observed for n–3 fatty acids have been attributed to the marine-derived long-chain n–3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid. In summary, it appears that ALA confers modest protection against CVD. Although the strength of the evidence is not nearly the same as for marine n–3 fatty acids, there is an increase in the number of studies in the past decade that support this protective association.
19. Vegetarians without EPA and DHA healthier than omnivores – How can vegetarians increase their blood and tissue concentrations of these animal-derived fatty acids? At present, both cardiovascular risk markers and cardiovascular events appear to be significantly reduced in vegetarians compared with those in omnivores. Could the risk in vegetarians be even lower with higher n–3 concentrations? The use of supplements containing EPA, DHA, or both derived from nonanimal sources (microalgae, biotech yeast, and, in the future, biotech plant oils) is possible
20. Vegetarian children may need zinc and iron fortified foods – Well-planned vegetarian diets are considered adequate for all stages of the life cycle, despite limited data on the zinc status of vegetarians during early childhood. The bioavailability of iron and zinc in vegetarian diets is poor because of their higher content of absorption inhibitors such as phytate and polyphenols and the absence of flesh foods. Existing data indicate no differences in serum zinc or growth between young vegetarian and omnivorous children. To reduce the risk of deficiency, the content and bioavailability of iron and zinc should be enhanced in vegetarian diets by consumption of fortified cereals and milk, by consumption of leavened whole grains, by soaking dried legumes before cooking and discarding the soaking water, and by replacing tea and coffee at meals with vitamin C–rich drinks, fruit, or vegetables.
21. Vegans may benefit from fortified foods for stronger bones – Some research suggests that vegetarian diets, especially vegan diets, are associated with lower bone mineral density (BMD), but this does not appear to be clinically significant. Vegan diets are not associated with an increased fracture risk if calcium intake is adequate. Dietary factors in plant-based diets that support the development and maintenance of bone mass include calcium, vitamin D, protein, potassium, and soy isoflavones. Fortified foods are often helpful in meeting recommendations for calcium and vitamin D. Plant-based diets can provide adequate amounts of key nutrients for bone health.
22. Plant-based diets required for a sustainable future for Earth – Plant-based diets in comparison to diets rich in animal products are more sustainable because they use many fewer natural resources and are less taxing on the environment. Given the global population explosion and increase in wealth, there is an increased demand for foods of animal origin. Environmental data are rapidly accumulating on the unsustainability of current worldwide food consumption practices that are high in meat and dairy products. Natural nonrenewable resources are becoming scarce, and environmental degradation is rapidly increasing. At the current trends of food consumption and environmental changes, food security and food sustainability are on a collision course. Changing course (to avoid the collision) will require extreme downward shifts in meat and dairy consumption by large segments of the world’s population. Other approaches such as food waste reduction and precision agriculture and/or other technological advances have to be simultaneously pursued; however, they are insufficient to make the global food system sustainable. Figure 3 shows how efficient various foods are at converting energy use into protein. Soybeans are the best plant protein, cheese is the best animal protein.
23. Food production may need to double over 40 years – Food sustainability and food security are increasingly in the spotlight and increasingly intertwined. According to some projections we will need to nearly double food production in the next 4 decades. This article argues that protein production and consumption are pivotal to sustainability, because anthropogenic contributions to the nitrogen cycle are 100–200% compared with a contribution of 1–2% to the carbon cycle by mineral fuel combustion, with biodiversity as the main casualty. Because 1 kg animal protein requires ∼6 kg plant protein, its large-scale production by means of factory farming is a major driver of biodiversity loss, climate change, and freshwater depletion. Furthermore, intensive livestock production is associated with antibiotics resistance and increasing incidence of emerging diseases. Therefore, a “reversed” diet transition back to less animal protein could make a difference.
24. Better health and lower greenhouse gas emissions with vegetarian diets – With the use of the nonvegetarian diet as a reference, the mean reductions in GHGEs for semivegetarian and vegetarian diets were 22% and 29%, respectively. The mortality rates for nonvegetarians, semivegetarians, and vegetarians were 6.66, 5.53, and 5.56 deaths per 1000 person-years, respectively. Moderate differences in the caloric intake of meat products provided nontrivial reductions in GHGEs and improved health outcomes.
25. Ancient Greek Pythagorus is father of ethical vegetarianism – 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 International Vegetarian Society was founded in 1908 and the first vegan society began in 1944. 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.
– Roc, Nutrition Investigator
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