You are what you eat? Plants, food, and human health

1. You are what you eat? Plants, food, and human health Image courtesy CDC and Mary Anne Fenley (number 13053) • What we get from food • Macronutrients, micronutrients and phytonutrients • How diet affects human health • Dietary deficiencies • Diet and chronic diseases • How can scientists promote better nutrition?

2. Carbohydrate metabolism Every cell in your body uses glucose to produce energy (ATP). Excess glucose is stored as glycogen (short-term storage) or fat Mikael Häggström

3. Carbohydrates - dietary fibers Fibers are gums, pectins and mucilages, celluloses and lignins. They affect nutrient uptake in the gut, and support beneficial intestinal microbes Oats, okra and legume seeds are good sources of soluble fibre Whole wheat foods or wheat bran, many vegetables, and fruit skins are good sources of insoluble fiber

4. Macronutrients - Proteins have many roles – enzymes, muscle, etc. Muscle meat, milk and eggs are concentrated sources of animal protein widely used as food, but every animal and plant cell contains protein. Legume seeds are particularly protein rich

5. Macronutrients Lipids: fats and oils Lipids are hydrocarbons, energy-rich compounds. Like gasoline, lipids release energy when oxidized. Plants and animals store energy as lipids, and lipids are also normal components of every cell and the basis of the cell membranes. At room temperature, fats are solid and oils are liquid, but both are lipids Many animal-derived foods are high in fat Oils are lipids extracted from plant seeds or fruits

6. Dietary omega-3 fatty acids can protect against chronic diseases ALA must be assimilated through the diet. DHA and EPA are produced from ALA with low efficiency DHA and EPA are produced by marine algae and accumulate in some fish, making fish good sources of beneficial omega-3 fatty acids α-linolenic acid (ALA) Eicosapentaenoic acid (EPA) Docosahexaenoic acid (DHA) Omega-3 fatty acids have been shown to have protective functions for cardiovascular disease, and, in rats, protect against neurodegeneration

7. Micronutrients – vitamins are essential small molecules Vitamin E Vitamin A Vitamin C, ascorbic acid Vitamins are essential nutrients that we need to eat because we cannot synthesize them Vitamin B9, folate Vitamin B1, thiamine Vitamin B3, niacine

8. Several dietary minerals are essential for human health Iron (Fe) is assimilated as heme (from animals) and non-heme (from plants) forms; non-heme iron, are less efficiently assimilated. Leafy greens and beans are sources of non-heme iron Potassium (K+) helps maintain osmotic balance and is abundant in fruits, beans, potatoes… Zinc (Zn2+) is found in animal-derived foods, beans and nuts Brazil nuts are an unusually good source of selenium(Se). The Se content of foods depends largely on soil content Calcium (Ca2+) is abundant in milk-products and green leafy vegetables

9. Phytonutrients can have long-term health benefits Coumarins Quinones Tannins Carbohydrate metabolism Flavonoids Glycosinolates Photo-synthesis Nitrogen metabolism Fatty acid metabolism Polyketides Primary metabolites Core compounds found in most organisms Cyanogenic glycosides Terpenes Alkaloids Secondary metabolites Often involved in defense or interactions with pollinators and often in only a few species Some plant “secondary metabolites” are phytonutrients Although phytonutrients have not been shown to be essential for human health in the same way that vitamins and minerals are, they may be important for long-term human health

10. Phytonutrients: flavonoids, anthocyanins and related compounds Cyanodin-glucoside, a reddish colored anthocyanin with numerous health benefits Genistein an isoflavonoid from soy beans Epigallocatechin gallate (EGCG), a flavonoid from green tea that may help eliminate immortality from some cancer cells Quercitin a flavonoid found in many plants Hesperetin a flavanone found in citrus fruits Curcumin from the spice turmeric has antioxidant and anti-inflammatory properties

11. Phytonutrients: carotenoids Carotenoids include β-carotene, the precursor to vitamin A, but also lutein, zeaxanthin and lycopene, which have health-promoting benefits Carotenoids are more than just vitamin A precursors lycopene β-carotene is converted to vitamin A after ingestion lutein Reprinted from Cazzonelli, C.I. and Pogson, B.J. (2010). Source to sink: regulation of carotenoid biosynthesis in plants. Trends Plant Sci. 15: 266-274 with permission from Elsevier. Corn photo by Doug Wilson.

12. Phytonutrients: allyl sulfides and isothiocyanates Broccoli (Brassica oleracea) Cabbage (Brassica oleracea) Garlic (Allium sativum) Onion (Allium cepa) Isothiocyanates such as sulforaphane are derived from cruciferous vegetables and have anti-cancer activities Allium species produce allyl sulfides with anti-cancer activities Diallyl disulfide Photos by Tom Donald, and Bruce Fritz ,and Jocelyn Eason, Plant and Food, New Zealand; Talalay, P. (2005). A fascination with enzymes: The journey not the arrival matters. J. Biol. Chem. 280:28829-28847.

13. How diet affects human health • Dietary deficiencies lead to disability and death • Diet is a factor in some chronic diseases • Type 2 diabetes • Cardiovascular disease • Cancer Photo credit: IRRI

14. More than one billion people are chronically hungry, and more than two billion people do not get adequate vitamins or minerals in their diet

15. There is a strong connection between diet and chronic disease Chronic diseases are by far the leading cause of mortality in the world, representing 60% of all deaths. Poor diet makes a significant contribution to the development of chronic diseases. Chronic diseases are one of the major health global health challenges, and the most effective strategy is through better nutrition In the US, 1/3 children will develop diabetes, and 2/3 adults are overweight Diabetes (millions) WHO; WHO/Chris de Bode : International Diabetes Foundation; Hossain, P., Kawar, B. and El Nahas, M. (2007). Obesity and diabetes in the developing world — A growing challenge. New England J. Med. 356: 213-215, PCRM

16. Diabetes is two diseases, type 1 and type 2; Type 2 is increasing rapidly Type I diabetes, ~10% of total, is an autoimmune disease that causes a loss of insulin production, and is usually diagnosed during childhood Type 2 diabetes is a largely a consequence of poor diet, obesity, and physical inactivity, and is usually diagnosed in adulthood. The incidence of Type 2 diabetes is increasing rapidly 2007 2025 (projection) Source: International Diabetes Foundation

17. Type 2 diabetes is preventable and reversible The not-so-secret “secret” • Maintain a healthy weight • Exercise frequently • Don’t smoke Photo credits: CDC/ Amanda Mills, Amanda Mills, Amanda Mills

18. Cardiovascular disease (CVD) is affected by blood lipid levels Reactive oxygen species Healthy levels of plasma lipids Damaged artery - the outer ring is the arterial wall, the rest is damage and plaque Triglycerides < 150 mg/dL or 1.7 mmol/L Total cholesterol < 200 mg/dL or 5 mmol/L LDL (low density lipoproteins) < 100 mg /dL or 3 mmol/L HDL (high density lipoproteins) > 60 mg/ dL or 1.56 mmol/L LDLs are prone to oxidation, which causes them to stick to arterial walls and form plaque Photo credit: Mark Shea

19. Dietary fruits and vegetables may decrease incidence of CVD There is compelling epidemiological support that dietary fruits and vegetables reduce heart disease Although the mechanisms remain uncertain, the evidence is compelling that plant-rich diets are desirable 40% 60% 80% 20% High blood pressure High cholesterol Current smoker Diabetes Percent of respondents No physical activity Overweight Failing to eat fruits and vegetables daily is correlated with CVD Not eating 5 servings of fruit or vegetables per day Image source: Centers for Disease Control and Prevention; CDC and James Gathany

20. Dietary fruits and vegetables can also contribute to cancer prevention • Eat more of a variety of vegetables, fruits, whole grains, and pulses such as beans • Limit consumption of energy-dense foods and avoid sugary drinks • Limit consumption of red meats and avoid processed meats • Don’t use supplements to protect against cancer. Aim to meet nutritional needs through diet alone • Be physically active for at least 30 minutes every day • Be as lean as you can without becoming underweight American Cancer Society; http://World Cancer Research Fund; Image courtesy CDC and James Gathany (number 130560)

21. How can scientists promote health and good nutrition? • Basic research to make healthy food available and affordable • Promote education about health and nutrition • Contribute to discussions about government’s roles What regulations should govern marketing to children? Should high-fat foods be taxed? Should schools teach cooking? Should “junk food” be banned?

22. Basic research contributes to food affordability Flooding-tolerant rice Virus-resistant tomatoes Broccoli that stays fresh longer Reprinted by permission from Macmillan Publishers Ltd. (NATURE) Xu, K., Xu, X., Fukao, T., Canlas, P., Maghirang-Rodriguez, R., Heuer, S., Ismail, A.M., Bailey-Serres, J., Ronald, P.C., and Mackill, D.J. (2006). Sub1A is an ethylene-response-factor-like gene that confers submergence tolerance to rice. Nature 442: 705-708. ; Broccoli photos courtesy Jocelyn Eason, Plant and Food, New Zealand; Anderson, L.K., Lai, A., Stack, S.M., Rizzon, C. and Gaut, B.S. (2006). Uneven distribution of expressed sequence tag loci on maize pachytene chromosomes. Genome Research. 16: 115-122; William M. Brown Jr., Bugwood.org Higher yields Less loss to drought, flooding, temperature extremes Less loss to pests and pathogens Improved shelf life Better understanding of plant biochemistry, nutrient uptake, photosynthesis, growth and development Improved tools for breeding and genomics

23. Plant scientists are working towards producing more nutritious foods Hotz, C., Loechl, C. de Brauw, A., Eozenou, P., Gilligan, D., Moursi, M., Munhaua, B., van Jaarsveld, P., Carriquiry A., and Meenakshi, J.V. (2012) A large-scale intervention to introduce orange sweet potato in rural Mozambique increases vitamin A intakes among children and women. Brit. J. Nutrit. (In press DOI: 10.1017/S0007114511005174). Photo courtesy HarevstPlus. What would happen if the foods we normally ate produced more health-enhancing nutrients?

24. Conclusions For millions of years humans have evolved to be broad, opportunistic eaters of diverse, low-calorie plant based diets Modern diets and too much of the wrong kinds of foods, leads to health problems, many stemming from obesity Scientists can help reverse the epidemic of chronic diseases through research, education and public policy Percent of Obese (BMI > 30) in U.S. Adults Photo credits: CDCNational Geographic