Drumstick tree (Moringa oleifera) leaves as a source of dietary selenium, sulphur, and pro-vitamin A

Authors: LYONS, G - University Of Adelaide; GONDWE, C - University Of Adelaide; Banuelos, Gary; MENDOZA, C - Former ARS Employee; HAUG, A - Norwegian University Of Life Sciences; CHRISTOPHERSEN, O - Norwegian University Of Life Sciences; EBERT, A - The World Vegetable Center (AVRDC) - Taiwan

Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: 6/19/2017
Publication Date: 7/7/2017
Citation: Lyons, G., Gondwe, C., Banuelos, G.S., Mendoza, C., Haug, A., Christophersen, O., Ebert, A. 2017. Drumstick tree (Moringa oleifera) leaves as a source of dietary selenium, sulphur, and pro-vitamin A. Acta Horticulturae. 287-292. doi: 10.17660/ActaHortic.2017.1158.32.
DOI: https://doi.org/10.17660/ActaHortic.2017.1158.32

Interpretive Summary: Various vitamins, especially vitamin A, are often deficient in human diets in many parts of Sub-Saharan Africa, especially when diets are based on low/zero-carotenoid staples such as white maize, white cassava and white sweet potato. Large vitamin A enhancement programs based on pills or capsules are expensive, of limited effectiveness and unsustainable in the long run. There is a need for increased production and consumption of nutritious local vegetables and fruit high in pro-vitamin A carotenoids, notably beta-carotene, in these vitamin A deficient countries and regions. When deep-rooted trees are removed in this part of Africa, the natural cycling of biophile elements (which are found at high absolute or relative concentrations in living organisms and include nitrogen, sulfur, phosphorus, potassium, selenium, iodine, zinc, boron and bromine) is disrupted, which usually leads to deficiencies of these nutrients in topsoil and crops, as well as in livestock and humans dependent on the crops. Research shows that the “drumstick tree” has exceptional ability to take up and accumulate the minerals selenium and sulfur in leaves, even when grown on soils where these are poorly available to other plants. There may be no other food plant which is equal or superior to “drumstick” in terms of its combination of nutritive, medicinal and disease preventive value, drought tolerance and ability to flourish on poor soils. Our study is based on surveys of foliar mineral, including selenium species, and carotenoid levels in a range of leafy vegetables from Sub-Saharan Africa. Results showed favorable concentrations of selenium and vitamin A in the edible drumstick leaves. Based upon our results, we recommend that drumstick be planted and its plant parts, especially foliage, be used to improve human and livestock nutrition and reduce disease risk in the tropics and sub-tropics.

Technical Abstract: The “drumstick tree” or “miracle tree” (Moringa oleifera) is well known for its high nutritional value. It grows well in tropical and sub-tropical regions, even on poor soils, is drought tolerant and produces abundant leaves high in protein (with a favorable amino acid balance), vitamins, minerals, and a range of beneficial phytocompounds. In this study, representative samples (n=250) of a range of leafy vegetables and wild edible leaves were collected from sites in Solomon Islands, Samoa, Tonga, Torres Strait Islands and Mourilyan, south of Cairns, Queensland. An effort was made to sample different species growing at the same site/on the same soil and common species from multiple sites/different soils. Data from a subset of samples including Drumstick leaves collected in Rwanda, East Africa were included. Drumstick is similar in most minerals, protein and carotenoid content to popular leafy vegetables. Additionally, it appears to be an exceptional accumulator of selenium and sulfur: its leaves accumulated around 12 times the concentration of selenium and around four times the concentration of sulfur compared to leaves of most other plants grown on the same soil, even when available levels of these minerals were low in the soil. The selenium speciation study found selenomethionine, the most common form of selenium in food, to be the dominant selenium form in drumstick leaves: mean 67% (SD 18%); selenodiglutathione 23% (20%); selenocysteine/selenocystine 4% (0.7%); unknown 4% (3%); selenite 1% (0.6%); methylselenocysteine 1% (0.3%). Selenomethionine is a bioavailable form, which is effective at increasing selenium status of humans and animals. Deficiencies of selenium, sulfur amino acids and vitamin A are common, especially in Sub-Saharan Africa and the present findings in the “drumsick tree” have important health and medical implications. Not only can the plant species improve human and livestock nutrition and reduce disease risk, its foliage can provide green manure for other food crops. We recommend that “drumstick” be planted and become part of the staple diet throughout this region and indeed globally in the tropics and sub-tropics.