Water Use for Food Production, Nutrition and Health WRC Dialogue - 17 October Friede Wenhold

Transcription

1 Water Use for Food Production, Nutrition and Health WRC Dialogue - 17 October 2014 Friede Wenhold

2 Aim of presentation: To o highlight food and nutrition findings, o present a ranking of water use / productivity of selected food groups, & o briefly explain Nutritional Water Productivity from WRC project K5/1954 Water use and nutrient content of crop and animal food products for improved household food security: a scoping study. (2012)

3 Context Under- South Africa Malnutrition Over- Imbalance Rural Poverty Strategies Foodbased Home-production Water-implications

4 Which FOODS are currently eaten? Sources of these foods? Why are these foods eaten? How can the current intake be improved (in given context)? Food selection guidance (FSG) What is WATER USE of ( home-producible ) items in FSG? What is nutrient content of items in FSG? What is NUTRITIONAL WATER PRODUCTIVITY (nutrient / m 3 water) of home-producible items in FSG?

5 Purpose

6 Which foods are currently eaten? Methods Replicable electronic search Hand searches, professional networks, etc Inclusion criteria (location, date, quantitative food intake information ranked, etc) Captured in project specific template

7 Which foods are currently eaten? Results 1. National Food Consumption Survey 1999

8 National Food Consumption Survey (1999) SA Food map: Colour-coded food icons/bars for 10 most frequently reported foods by province

9 Which foods are currently eaten? 2. KwaZulu-Natal: certain sites well covered Ndunakazi (Young children [4-24mo; 2-5y; 10-11y; 25-55y]) Valley of a Thousand Hills (KwaXimba) (households; 6-12mo) Umkhanyakude & Zululand (Nongoma & Pongola sub-districts) (6-12mo; 2-5y) Northern KZN (6-12mo)

10 Which foods are currently eaten? 3. Limpopo: some data for different sites Sovenga (UNIN students) Dikgale (adults) Sekhukhune district (households) Vhembe (infants; students) Central Region (1-3y; 12-24mo) Arthurstone, Mars & Glenroy (focus on leaves) Bushbuckridge (household food acquisition)

11 Which foods are currently eaten? 4. Rest of country Eastern Cape (OR Tambo & Alfred Nzo districts) Free State North West (Thusa) Western Cape Very limited number of studies Mpumalanga Gauteng Northern Cape no studies

12 Challenges: Only one national survey (done in 1999; did not disaggregate rural poor) Smaller studies: - non-representative coverage geographically sampling life stage & ethnicity - often not the primary objective of the study - some studies focused on specific foods

13 Challenges: Smaller studies: (cont) - different ways of reporting and grouping of foods groups (e.g. fruit versus apple) dishes (e.g. samp-and-beans) individual foods (e.g. samp, legumes) different types of a specific food (e.g. bread brown bread & white bread)

14 Challenges: Smaller studies: (cont) - only studies with quantitative data - major food items - current intake - different ways of ranking the foods number of times reported number (%) of respondents consuming the food total amount consumed

15 Conclusion: Preliminary (food-based) trends: - Cereal-based (maize, bread, rice) - Low intakes of fruit, vegetables, animal-source foods - Provincial differences: - Limpopo province: green leafy vegetables - Western Cape differs from other provinces Insufficient evidence to compile one basket of contemporary food intake of poor rural households in South Africa

16 SOURCES OF FOOD Insufficient data for generalisation Buy maize meal, wheat, bread, salt Purchasing major mode of procurement for other foods Home-production limited and uncertain nutritional contribution From the wild regional, mostly leaves

17 In general: The nutritional problems of South Africans: 1. Energy and macronutrient (protein) status 2. Micronutrient malnutrition 3. Dietary diversity 4. Nutrient density

18 1. Energy and macronutrient (protein) status Energy: Protein: Children: Overall intakes of energy inadequate, but at the same time childhood obesity is increasing Adults: Obesity common among women in rural areas Total intakes adequate, but biological value (of mainly plant source protein) may be a concern.

19 2. Micronutrient status Among SA children - High prevalence of Low retinol levels (poor vit. A status) Low zinc status Anaemia & poor iron status Hidden hunger is a major cause of concern.

20 3. Dietary diversity Overall South Africans consume monotonous diets: diets lack diversity Intake of fruit and vegetables is low

21 4. Nutrient density Nutrient density: Amount of (micro)nutrients relative to energy content (or volume) of the diet or of a food Porridge (made from maize meal) and bread are the staples of many South Africans. Both have a low micronutrient density. ( Fortification!)

22 Nutritional status is influenced by multiple and interrelated factors. FOOD CARE HEALTH Poverty is the root cause of malnutrition In South Africa people living in rural areas are most affected by malnutrition

23 FOOD for good nutritional A healthy diet is: status & health Balanced / proportional (in line with the SA-Food Based Dietary Guidelines & international DRI s) Varied (different foods from the various food groups) Moderate (to prevent overnutrition)

24 FOOD selection guidance for homeproduction / agronomists Overall guiding principles: SA Food Based Dietary Guidelines Micronutrient deficiencies - public health relevance (vitamin A, iron, zinc) Sustainable (agro-ecologically, economically and socio-culturally) Focus on non-staples

25 FOOD selection guidance for homeproduction / agronomists Non-staples should address nutritional gaps + consider dietary requirements of (vulnerable) target groups micronutrient malnutrition in children obesity and chronic disease in adults immune compromised groups take regional differences in intake into account

26 FOOD selection guidance for homeproduction / agronomists Non-staples: Additional considerations Do support systems exist for o the agronomic component? o nutrition education and promotion? Continuous supply of affordable planting material (seed systems / high quality seeds / seedlings / farming system)

27 Preliminary food selection guidance Using a 2-5 year old child in rural KZN as target: Non-staple crops: Yellow / orange vegetables: Yellow pumpkins, incl. butternut Orange-fleshed sweet potato Carrots Dark green leafy vegetables, wild & home-grown: Swiss chard / Spinach Amaranthus Yellow / orange fruits (excl. citrus): Papaya Mango In addition to current crops planted! Plus: Animal-source foods Legumes

28 Water productivity WATER in crop production Water use / productivity In the case of plants, water productivity considers the yield of a crop relative to the water used to produce it be it from rainfall, irrigation or groundwater and taking into account productive and unproductive water losses. It is typically expressed as kilograms of crop per cubic metre water. Water productivity = Yield (biomass) in kg per m 3 water transpired

29 Water productivity Water productivity is influenced by multiple and interrelated factors. For crops the most important factors can be grouped under these broad categories: CLIMATE Radiation Wind speed Temperature Relative humidity CROP TYPE Harvest index Fraction of crop used as food Within the crop type: Leaf shape and stomata properties, canopy, total growing period, composition (% dry matter) etc.

30 Water productivity WATER in crop production Most productive A general ranking of water use efficiency of food crops types from most to least efficient, would be 1. from vegetables 2. to fruits 3. then to cereals, 4. oil crops and 5. lastly legumes. Vegetables are largely composed of water and a major part of the plant is harvested (high harvest index). Least productive On the other hand, legumes are harvested dry and contain significant amounts of protein (growing period & composition).

31 Water productivity WATER in livestock production For animal-source foods, some water is used by livestock for drinking. By far the most is used in the production of feed ( previous considerations about plant water productivity again apply). Processing of carcasses into meat and other (edible) outputs also depletes water.

32 Water productivity WATER in livestock production Most productive Overall: Animal-source products are less water efficient than crops. Amongst the animal source foods a ranking from highest to lowest water productivity would be from milk and eggs, to chicken and pork, to small stock (sheep and goats) and lastly to beef. Least productive

33 Nutritional water productivity Nutritional water productivity (NWP) This novel concept combines knowledge of the composition of food products in terms of nutrients (for example the protein or vitamin A content of a food) with knowledge of the water productivity of that food product. The result is an index for a given food product which includes nutrient-based output per unit water use. Example: μg β-carotene in 100g raw spinach per cubic metre of water used to produce the spinach. NWP = (Harvested yield [kg per ha] x Nutrient content [nutrition unit per kg]) Evapotranspiration [m 3 per ha]

34 Nutritional water productivity Nutritional water productivity Example 1: Orange sweet potato The water productivity of orange sweet potato is 5.2 kg / m 3 Orange sweet potato has the following nutrient content per kg: Energy: 4.5 MJ Protein: 17 g The nutritional water productivity would thus be: Energy: 23.2 MJ/m 3 Protein: 88 g /m 3 Per cubic meter of water used, sweet potatoes yield 23.2MJ of energy and 88 g of protein.

35 Nutritional water productivity Nutritional water productivity Example 2: Spinach The water productivity of spinach is 3.2 kg / m 3 Spinach has the following nutrient content per kg Energy: 1.3 MJ Protein: 27 g The nutritional water productivity would thus be Energy: 4.1 MJ/m 3 Protein: 86 g/m 3 Spinach yields 4.1 MJ of energy and 86 g of protein per cubic meter of water used.

36 Nutritional water productivity Nutritional water productivity Conclusion: Knowledge about nutritional water productivity can be used to promote the production of those food products that may contribute to closing the nutrient gaps in vulnerable South African communities while, at the same time, leaving a sustainable water footprint. For a particular target group (e.g. children in Limpopo) one needs to remember how much of and how often a particular food (e.g. sweet potato) is typically consumed, before active promoting for addressing a specific form of malnutrition. Knowledge about nutritional water productivity must be embedded in an understanding of the eating habits and the factors influencing these in the vulnerable group to be targeted (e.g. cultural factors, food security ). VARIETY, BALANCE and MODERATION remain the pillars of healthy eating.

37 Acknowledgements Project Team: WRC Project K5/1954 John Annandale: Plant Production & Soil Science, UP Mieke Faber: Non-Communicable Diseases Research Unit, MRC Tim Hart: Human Sciences Research Council Andre Oelofse: (formerly) Centre for Nutrition, UP WRC: Reference Group members