Moringa oleifera:
A Review of the Medical Evidence for
Its Nutritional, Therapeutic, and Prophylactic Properties. Part 1.
Jed W. Fahey
PEER REVIEWED: The Moringa tree (Moringa
oleifera) has been praised for its nutritional and medicinal
properties, and many claims have been made regarding its benefits. This first
in a series of brief reviews looks at the published scientific evidence on this
tree.
PEER REVIEWED: Johns Hopkins School of Medicine,
Department of Pharmacology and Molecular Sciences, Lewis B. and Dorothy Cullman
Cancer Chemoprotection Center, 725 N. Wolfe Street, 406 WBSB, Baltimore,
Maryland, USA 21205-2185. Email:
jfahey@jhmi.edu
Trees for Life Journal 2005, 1:5.The electronic version of this article is the complete one and can be found
online at: http://www.tfljournal.org/article.php/20051201124931586
Received: September 15, 2005; Accepted: November
20, 2005; Published: December 1, 2005
Copyright: ©2005 Jed W. Fahey
This is an Open Access article distributed under the terms of the Creative
Commons Attribution License which permits unrestricted use, distribution, and
reproduction in any medium, provided the original work is properly cited.
Moringa appears to be a
nutritional and medicinal cornucopia. The author, a Western-trained nutritional
biochemist who has studied some of Moringa’s phytochemicals for almost a
decade, gives a brief commentary and extensive references, and presents a table
introducing some of the tree’s most intriguing features. This is the first
article in a series, and will be followed by more detailed analysis of some of
the strongest claims made regarding this edible plant.
Abstract
Moringa oleifera, or the horseradish tree, is a pan-tropical
species that is known by such regional names as benzolive, drumstick tree,
kelor, marango, mlonge, mulangay, nébéday, saijhan, and sajna. Over the past
two decades, many reports have appeared in mainstream scientific journals
describing its nutritional and medicinal properties. Its utility as a non-food
product has also been extensively described, but will not be discussed herein,
(e.g. lumber, charcoal, fencing, water clarification, lubricating oil).
As with
many reports of the nutritional or medicinal value of a natural product, there
are an alarming number of purveyors of “healthful” food who are now promoting M.
oleifera as a panacea. While much of this recent enthusiasm indeed appears
to be justified, it is critical to separate rigorous scientific evidence from
anecdote. Those who charge a premium for products containing Moringa
spp. must be held to a high standard. Those who promote the cultivation and use
of Moringa spp. in regions where hope is in short supply must be
provided with the best available evidence, so as not to raise false hopes and
to encourage the most fruitful use of scarce research capital. It is the
purpose of this series of brief reviews to: (a) critically evaluate the
published scientific evidence on M. oleifera, (b) highlight claims
from the traditional and tribal medicinal lore and from non-peer reviewed
sources that would benefit from further, rigorous scientific evaluation, and
(c) suggest directions for future clinical research that could be carried out
by local investigators in developing regions.
This is the first of four planned papers on the nutritional,
therapeutic, and prophylactic properties of Moringa oleifera. In this
introductory paper, the scientific evidence for health effects are summarized
in tabular format, and the strength of evidence is discussed in very general
terms. A second paper will address a select few uses of Moringa in greater
detail than they can be dealt with in the context of this paper. A third paper
will probe the phytochemical components of Moringa in more depth. A
fourth paper will lay out a number of suggested research projects that can be
initiated at a very small scale and with very limited resources, in geographic
regions which are suitable for Moringa cultivation and utilization.
In
advance of this fourth paper in the series, the author solicits suggestions and
will gladly acknowledge contributions that are incorporated into the final
manuscript. It is the intent and hope of the journal’s editors that such a
network of small-scale, locally executed investigations might be successfully
woven into a greater fabric which will have enhanced scientific power over
similar small studies conducted and reported in isolation. Such an approach
will have the added benefit that statistically sound planning, peer review, and
multi-center coordination brings to a scientific investigation.
The following paper is intended to be useful for both scientific and lay
audiences. Since various terms used herein are likely not familiar to the lay
reader, nor are many of the references readily available to either scientific
or lay audiences, we encourage active on-line dialog between readers and both
the author and the journal staff. Both will attempt to answer questions and to
direct readers to the experts in an open and public manner.
Introduction
Moringa oleifera is the most widely cultivated species of a
monogeneric family, the Moringaceae, that is native to the sub-Himalayan tracts
of India, Pakistan, Bangladesh and Afghanistan. This rapidly-growing tree (also
known as the horseradish tree, drumstick tree, benzolive tree, kelor, marango,
mlonge, moonga, mulangay, nébéday, saijhan, sajna or Ben oil tree), was
utilized by the ancient Romans, Greeks and Egyptians; it is now widely
cultivated and has become naturalized in many locations in the tropics. It is a
perennial softwood tree with timber of low quality, but which for centuries has
been advocated for traditional medicinal and industrial uses. It is already an
important crop in India, Ethiopia, the Philippines and the Sudan, and is being
grown in West, East and South Africa, tropical Asia, Latin America, the
Caribbean, Florida and the Pacific Islands.
All parts of the Moringa tree are
edible and have long been consumed by humans. According to Fuglie (47) the many
uses for Moringa include: alley cropping (biomass production), animal forage
(leaves and treated seed-cake), biogas (from leaves), domestic cleaning agent
(crushed leaves), blue dye (wood), fencing (living trees), fertilizer
(seed-cake), foliar nutrient (juice expressed from the leaves), green manure
(from leaves), gum (from tree trunks), honey- and sugar cane juice-clarifier
(powdered seeds), honey (flower nectar), medicine (all plant parts), ornamental
plantings, biopesticide (soil incorporation of leaves to prevent seedling
damping off), pulp (wood), rope (bark), tannin for tanning hides (bark and
gum), water purification (powdered seeds). Moringa seed oil (yield 30-40% by
weight), also known as Ben oil, is a sweet non-sticking, non-drying oil that
resists rancidity. It has been used in salads, for fine machine lubrication,
and in the manufacture of perfume and hair care products (158).
In the West,
one of the best known uses for Moringa is the use of powdered seeds to
flocculate contaminants and purify drinking water (11,50,113), but the seeds are
also eaten green, roasted, powdered and steeped for tea or used in curries
(50). This tree has in recent times been advocated as an outstanding indigenous
source of highly digestible protein, Ca, Fe, Vitamin C, and carotenoids
suitable for utilization in many of the so-called “developing” regions of the
world where undernourishment is a major concern.
Nutrition
Moringa trees have been used to combat malnutrition, especially among
infants and nursing mothers. Three non-governmental organizations in particular—Trees
for Life, Church World Service and Educational Concerns for Hunger
Organization—have advocated Moringa as “natural nutrition for the
tropics.” Leaves can be eaten fresh, cooked, or stored as dried powder for many
months without refrigeration, and reportedly without loss of nutritional value.
Moringa is especially promising as a food source in the tropics because the
tree is in full leaf at the end of the dry season when other foods are
typically scarce.
A large number of reports on the nutritional qualities of Moringa now exist
in both the scientific and the popular literature. Any readers who are familiar
with Moringa will recognize the oft-reproduced characterization made many years
ago by the Trees for Life organization, that “ounce-for-ounce, Moringa leaves
contain more Vitamin A than carrots, more calcium than milk, more iron than
spinach, more Vitamin C than oranges, and more potassium than bananas,” and
that the protein quality of Moringa leaves rivals that of milk and eggs. These
readers will also recognize the oral histories recorded by Lowell Fuglie in
Senegal and throughout West Africa, who reports (and has extensively documented
on video) countless instances of lifesaving nutritional rescue that are
attributed to Moringa (47,48). In fact, the nutritional properties of Moringa
are now so well known that there seems to be little doubt of the substantial
health benefit to be realized by consumption of Moringa leaf powder in
situations where starvation is imminent. Nonetheless, the outcomes of well
controlled and well documented clinical studies are still clearly of great
value.
In many cultures throughout the tropics, differentiation between food and
medicinal uses of plants (e.g. bark, fruit, leaves, nuts, seeds, tubers, roots,
flowers), is very difficult since plant uses span both categories and this is
deeply ingrained in the traditions and the fabric of the community (85). Thus,
Table 1 in this review captures both nutritional and medicinal references as
they relate to Moringa, whilst avoiding most of the better known agro-forestry
and water purification applications of this plant. The interested reader is
also directed to the very comprehensive reviews of the nutritional attributes
of Moringa prepared by the NGOs mentioned earlier (in particular, see
references 47,123,157).....
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