Nutritional composition of Zulu dishes

Nutritional composition of commonly consumes composite dishes from rural villages in Empangeni, Kwa-Zulu Natal. South Africa. was published on JHND Early View in December 2012.  Professor Una MacIntyre of the Faculty of Health Sciences University of Pretoria has provided the comments published below. The views expressed are solely those of the authors. Dr Sharma and colleagues have been invited to make a response.

Dear Editor

We refer to the article by Spearing et al (2012) entitled: Nutritional composition of commonly consumed composite dishes from rural villages in Empangeni, Kwa-Zulu Natal.

We are in agreement with the authors that information on the nutrient composition of composite dishes would be helpful in characterising the dietary intakes of the population of Kwa-Zulu Natal.  There is however, concern about the credibility of the results given and conclusions drawn in the article.

In the Materials and Methods section, the authors state that the USDA National Nutrition Database for Standard Reference was used for the nutrient analyses ‘because the food composition database for South Africa is limited in the number of foods and nutrients. The USDA database provides a complete nutrient profile … as opposed to the South African database which only provides five nutrients per food item.

This statement is blatantly incorrect.  The South African Food Composition database, contained in the South African Food Data System (SAFOODS) and developed and managed by the South African Medical Research Council (SAMRC), comprises 1472 food items and reports values for 145 nutrients and food components (SAMRC, 2012). The reference cited by Spearing et al (2012) (Medical Research Council of South Arica (2010)) refers to the open access, online database, which is an extract of the comprehensive SAFOODS and is not meant for use by nutrition professionals or researchers.    It is a concern that the authors consulted neither the SAMRC directly concerning the analysis of their data nor consulted published South African dietary intake studies (Faber  et al., 2001, MacIntyre et al., 2002; Schutte et al.,2003; Labadarios et al., 2005; Delport et al., 2010 ) which indicate the use of the  South African Food Composition database and present the same  nutrients as  reported by Spearing et al.(2012).  Furthermore, a condensed, printed version of the SAFOODS is available from the SAMRC (Wolmarans et al., 2010).

Spearing et al. (2012) acknowledge that ‘slight variations may have occurred as a result of food composition data’.   Since Spearing et al (2012) fail to provide the amounts of the ingredients used in the reported recipes, we were unable to calculate the nutrient composition of the composite dishes. ‘Putu’ (crumbly maize meal porridge) and ‘Stifpap’ (stiff maize meal porridge) however, are simple mixtures of maize meal and water, for which nutrient composition is available in the South African Food Composition database.  While a comparison of the energy and macronutrient composition provided by South African Food Composition Tables (Wolmarans et al., 2010) and those of Spearing et al. (2012) show relatively small differences, Table 1 shows that the differences in vitamin and mineral values are considerable.

Table 1: Comparison of the micronutrient composition  of ‘Putu’ (fortified crumbly maize meal porridge) and ‘Stifpap’ (fortified stiff maize meal porridge) of Spearing et al (2012) and the South African Food Composition Tables (Wolmarans et al., 2010) (per 100g)

Spearing et al. (2012) South Afican Food Composition Tables (Wolmarans et al., 2010)
1‘Putu’ 2 ‘Stifpap’ 1Fortified crumbly maize meal porridge  (53g water; 47g maize meal) 2Fortified stiff maize meal porridge (73g water;  27g maize meal)
Vitamin A (μgRAE) 0 1.7 86 40
Thiamin (mg) 0.62 0.11 0.43 0.23
Riboflavin (mg) 0.29 0.08 0.11 0.08
Niacin (mg) 4.5 1.0 1.1 0.6
Pantothenic acid (mg) 0.4 0.1 0.21 0.12
Vitamin B6 (mg) 0.03 0.05 0.305 0.195
Total Folate (μg) 114 43 79 52
Vitamin B12 (mg) 0 0.02 0 0
Vitamin C (mg) 0 0 0 0
Vitamin D (IU) 0 0.9 0 0
Vitamin E (IU) 0 0 0.39 0.22
Calcium (mg) 4 4 4 4
Magnesium (mg) 11 8 43 24
Potassium (mg) 71 29 135 71
Sodium (mg) 91 88 8 7
Iron (mg) 2.4 0.9 2.4 1.4
Zinc (mg) 0.4 0.1 1.65 0.91

1 ‘Putu’ is equivalent to crumbly maize meal porridge

2 ‘Stifpap’ is equivalent to stiff maize meal porridge.

The South African Food Composition Tables provide higher vitamin A, vitamin E, vitamin B6, potassium and zinc values for both ‘Putu’ (crumbly maize meal porridge) and ‘Stifpap’ (stiff maize meal porridge) and higher thiamin and iron values for ‘stifpap’ (stiff maize meal porridge).  The values of niacin and pantothenic acid given for ‘stifpap’ (stiff maize meal porridge) by the South African Food Composition Tables are lower than those given by Spearing et al (2012), as are the values of thiamin and folate for ‘putu’ (crumbly maize meal porridge). In light of the similarity in energy contents, the differences cannot be explained by differences in consistency, but by the micronutrient fortificant mixture developed to address the specific deficiency risk micronutrients of the South African population (Editorial, 2003).  The use of the results of Spearing et al (2012) for the analysis of dietary intakes of the target population will therefore provide inaccurate conclusions and possible inappropriate interventions.

It is not clear why Table 3 (Spearing et al 2012) gives  the Vitamin A and vitamin D content of ‘stifpap’ of 1.7 μg-RAE  and 0.9 mg respectively, while these values for ‘Putu’ are reflected as 0.  Since ‘stifpap’ has a lower maize meal to water ratio than ‘Putu’, if ‘Putu’ lacks these nutrients, then so should ‘stifpap’.

Since Spearing et al. (2012), have presented only the nutrient content of what they identify as ‘commonly consumed composite dishes’ (without any explanation of how a composite dish was identified as ‘common’), and have provided neither an indication of amounts of composite dishes consumed nor of the total dietary intake, their reference to their results as ‘baseline data’ is not supported.  While the meat and vegetable composite dishes appear to have a high fat content and the recommendation to reduce the use of fat in food preparation appears reasonable, without information about the total dietary intake of the population these conclusions cannot be supported.

The publication of an article which not only presents incorrect facts, but also questionable conclusions by a highly respected journal such as the Journal of Human Nutrition and Dietetics is concerning as it calls the review and editorial process into question. It is incumbent on the Journal to publish a correction and to apologise not only to the South African MRC, but also to the South African Nutrition community, for misrepresenting the South African Food Composition Database, which is the basis of nutrition science and research.

References

Delport, R., Bornman, R., MacIntyre, U.E.,Oosthuizen, N.M., Becker, P.J., Aneck-Hahn, N.H., de Jager, C. (2011) Changes in retinol binding protein concentrations and thyroid homeostasis in nonoccupational exposure to DDT. Environmental Health Perspectives.119, 647-651.

Editorial Office (2003). Food fortification becomes a reality in South Africa. SAJCN  16, 39.

Faber, M., Jogessar, V.B. & Benade, A.J.S. (2001). Nutritional status and dietary intakes of children aged 2-5 years and their caregivers in a rural South African Community. International Journal of Food Science and Nutrition. 52, 401-411.

Labadarios, D., Steyn, N.P., Maunder, E. et al. (2005). The National Food Consumption Survey (NFCS): South Africa, 1999. Public Health Nutrition. 8(5),533-543.

MacIntyre, U.E., Kruger, H.S., Venter, C.S. &  Vorster, H.H. (2002)Dietary intakes of an African population in different stages of transition in North West Province, South Africa: the THUSA study.Nutrition Research 22, 239-256.

Schutte, A.E., van Rooyen, J.M., Huisman, H.W., Kruger, H.S., Malan N.T. & De Ridder, J.H. (2003). Dietary markers of hypertension associated with pulse pressure and arterial compliance in black South African children. Cardiovasc J South Afr.  14, 81-89.

South African Medical Research Council (2012). SAFOODS. South African Food Database System.Available at http://safoods.mrc.ac.za/. (Accessed on 28 February 2012).

Spearing, K., Kolahdooz, F., Lukaswich, M., Mathe, N., Khamis, T. & Sharma, S. (2012). Nutritional composition of commonly consumes composite dishes from rural villages in Empangeni, Kwa-Zulu Natal. South Africa. J Hum Nutr Diet.  Doi:10.111/jhn.12001.

Wolmarans, P., Danster N., Dalton A., Rossow, K. & Schonveldt, H. (eds). (2010). Condensed food composition tables for South Africa. Parow Valley, Cape Town: Medical Research Council.

U E MacIntyre,  PhD

G Gericke, MSc

F Wenhold, PhD

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