Measuring the Affordability of Nutritious Diets in Africa: Price Indexes for Diet Diversity and the Cost of Nutrient Adequacy

American Journal of Agricultural Economics, Forthcoming

Invited paper presented at the ASSA (January 2018)

43 Pages Posted: 19 May 2017 Last revised: 26 Jun 2018

William A. Masters

Tufts University - Friedman School of Nutrition Science and Policy; Tufts University - Department of Economics

Yan Bai

Tufts University - Friedman School of Nutrition Science and Policy

Anna Herforth

Tufts University - Friedman School of Nutrition Science and Policy

Daniel Sarpong

University of Ghana - Department of Agricultural Economics and Agribusiness

Fulgence Mishili

Sokoine University of Agriculture

Joyce Kinabo

Sokoine University of Agriculture

Jennifer Coates

Tufts University - Friedman School of Nutrition Science and Policy

Date Written: June 3, 2018

Abstract

Policies and programs often aim to improve the affordability of nutritious diets, but existing food price indexes are based on observed quantities which may not meet nutritional goals. To measure changes in the cost of reaching international standards of diet quality, we introduce a new Cost of Diet Diversity (CoDD) index based on the lowest-cost way to include at least five different food groups as defined by the widely-used Minimum Dietary Diversity for Women (MDD-W) indicator, and compare that to a Cost of Nutrient Adequacy (CoNA) indicator for the lowest-cost way to meet estimated average requirements of essential nutrients and dietary energy as defined by Dietary Reference Intake (DRI) values for an adult woman. We demonstrate application of both indexes using national average monthly prices from two very different sources: an agricultural market information system in Ghana (2009-14), and the data used for national consumer price indexes in Tanzania (2011-15). We find that the CoDD index for Ghana fluctuated seasonally and since mid-2010 rose about 10 percent per year faster than national inflation, due to rising relative prices for fruit, which also drove up the cost of nutrient adequacy. In Tanzania there were much smaller changes in total daily costs, but more adjustment in the mix of food groups used for the least-cost diet. These methods can show where and when nutritious diets are increasingly (un)affordable, and which nutritional criteria account for the change. These results are based on monthly national average prices, but the method is generalizable to other contexts for monitoring, evaluation, and assessment of changing food environments.

Keywords: Food Prices, Diet Quality, Diet Diversity, Nutrient Adequacy, CPI

JEL Classification: Q11, Q18, I15

Suggested Citation

Masters, William A. and Bai, Yan and Herforth, Anna and Sarpong, Daniel and Mishili, Fulgence and Kinabo, Joyce and Coates, Jennifer, Measuring the Affordability of Nutritious Diets in Africa: Price Indexes for Diet Diversity and the Cost of Nutrient Adequacy (June 3, 2018). American Journal of Agricultural Economics, Forthcoming; Invited paper presented at the ASSA (January 2018). Available at SSRN: https://ssrn.com/abstract=2970745 or http://dx.doi.org/10.2139/ssrn.2970745

William A. Masters (Contact Author)

Tufts University - Friedman School of Nutrition Science and Policy ( email )

150 Harrison Avenue
Boston, MA 02111
United States

HOME PAGE: http://sites.tufts.edu/willmasters

Tufts University - Department of Economics ( email )

Medford, MA 02155
United States

Yan Bai

Tufts University - Friedman School of Nutrition Science and Policy ( email )

150 Harrison Avenue
Boston, MA 02111
United States

HOME PAGE: http://ianda.nutrition.tufts.edu/team/yan-bai-mib

Anna Herforth

Tufts University - Friedman School of Nutrition Science and Policy ( email )

150 Harrison Avenue
Boston, MA 02111
United States

HOME PAGE: http://ianda.nutrition.tufts.edu/team/anna-herforth-phd

Daniel Sarpong

University of Ghana - Department of Agricultural Economics and Agribusiness ( email )

Accra
India

HOME PAGE: http://ianda.nutrition.tufts.edu/team/daniel-bruce-sarpong-phd

Fulgence Mishili

Sokoine University of Agriculture ( email )

PO Box 3000
Morogoro
Tanzania

HOME PAGE: http://ianda.nutrition.tufts.edu/team/fulgence-mishili-phd

Joyce Kinabo

Sokoine University of Agriculture ( email )

PO Box 3000
Morogoro
Tanzania

HOME PAGE: http://ianda.nutrition.tufts.edu/team/joyce-kinabo-phd

Jennifer Coates

Tufts University - Friedman School of Nutrition Science and Policy ( email )

150 Harrison Avenue
Boston, MA 02111
United States

HOME PAGE: http://https://nutrition.tufts.edu/profile/faculty/jennifer-coates

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