I am on holidays in the beautiful Sonoran desert, Arizona, and was told by the hotel gardener that many of the locals eat Moringa leaves to manage pre-diabetes and diabetes. Always the researcher (even on vacation), I had to try the leaves for myself. The leaves tasted pleasant enough, but do they actually have any health benefits?
A quick (covert) poolside internet search on my cell phone confirmed that the blogosphere agrees with the gardener’s claim that “Moringa has antidiabetic properties.” Additionally, Moringa is purported to offer over 300 medical benefits, including antibacterial, anti-inflammatory, anti-ulcer, anticancer, and anti-asthma properties.
Even on vacation, I simply have to do my own research. It is a pity that the “uncut” blogosphere is so unreliable and predictably inaccurate. Even worse, the viral nature of the internet means that misinformation can spread so easily.
I had to do my own research. Feeling a little guilty, I sat under the shade of a large Moringa tree and checked out its credentials as a “natural superfood” and “miracle tree.”
What Is Moringa?
Moringa (aka horse radish/drumstick tree) is an edible plant which is native to Asia and Africa. So how exactly was I enjoying the shade of a Moringa in Arizona? It seems that British colonists brought the tree from India to Africa and Jamaica. Thanks to globalization, Moringa has been planted around the world and is now cultivated worldwide.
India is the largest producer of Moringa worldwide, with an annual production of 1.3 million tons. There are 13 different species of Moringa, with Moringa oleifera being the most-used and most-studied species. There is high heterogeneity in both the form and yield of Moringa, which is very relevant when it comes to interpreting the literature on the subject, as we will see.
Moringa is a hardy tree which requires less than 800mm per year of irrigation. It grows quickly and can reach heights of 12 m in just a few years. On the plus side, that means Moringa is seen as a reliable crop, but on the negative side, it is discriminated in poorer countries as just a “famine food.”
Historically, Moringa was used back in ancient Egypt as a cosmetic and is still widely used in Ayurvedic or traditional Indian medicine. Interest in Moringa peaked in the 1990s with the recognition that Moringa was useful for purifying water. Moringa contains charged particles which repel similarly charged particles in natural water, and thus acts as a natural filtration system. From there, interest in the tree grew. Fast-forward a decade to 2001, when an international conference on Moringa was held in Tanzania. There are now a number of research centers focusing on Moringa (India, Taiwan, Zambia, and the Philippines).
There are three main parts of the tree: leaves, seeds, and flowers.
Seven categories of use (food, medicine, fodder, fencing, firewood, gum, and coagulant) have been recorded for Moringa oleifera.
Generally speaking, the leaves and seeds of the tree are used as food, while the leaves, bark, and root are used as medicinal products.
Looking in more detail at the medicinal uses of Moringa, we find that the:
leaves are used for malaria, typhoid, parasitic infections, arthritis, hypertension, diabetes, immune boosting, cardiac stimulation, contraception, and as a lactation aid
seeds are used for stomach ulcers, toothache, poor vision, hemorrhoids, and as biomass for biodiesel production
roots are used as a “sex enhancer”
flowers are used as an aphrodisiac, to treat hysteria and enlargement of the spleen.
Quite the list!
There are 6,000 Moringa-related products for sale on Amazon. Moringa derivative products include powder, seeds, capsules, tea, and oil. Costs run as high as $1 per oz for fine powder and $5 per fluid oz for Moringa oil.
Moringa leaves contain a multitude of compounds, including vitamins (E and C), minerals (calcium, phosphorus, potassium, sulphur, zinc, copper, manganese, iron, selenium), protein, fiber, lysine, tannins, cellulose, polyphenols, and quercetin.
Some blogs have claimed that Moringa leaves contain “seven times the amount of vitamin C as oranges” and “four times the amount of vitamin A as carrots.” Really?
Let’s start with vitamin A.
Fresh Moringa leaves contain between 11,000 IU and 23,000 IU of vitamin A. They also contain carotenoids with pro-vitamin A activity. The carotenoid content varies between 6.6 and 6.8 mg/100 g for fresh leaves of Moringa and 17.6 to 39.6 mg/100 g for dried leaves. Overall, beta-carotene is more concentrated in the dried leaves (1).
This is different to vitamin C, where the vitamin C content in fresh leaves is higher than in dried leaves, as vitamin C is sensitive to heat and oxygen. Typical levels of vitamin C in fresh leaves are 200 mg/100 g but drops to 18.7 mg/100 g for dried leaves (to put this into context, fresh oranges contain 37.4 mg/100 g of vitamin C). Some studies have found no vitamin C at all in dried Moringa leaves (1).
What does all this mean in simple English? Hard to know exactly.
- There is huge variability in the content of different Moringa preparations, which makes it very difficult to make any generalization or meaningful comparisons to other nutrient-dense foods. Different plant genetics, environmental conditions, extraction, drying, and analytical methods account for the wide variability noted between different Moringa preparations. Some Moringa preparations may be a rich source of vitamin C and some are not. The uncertainty makes it hard to rely on Moringa for vitamin C. Anyway, looking at the tree above me, only a giraffe could eat 100 g of leaves. It is far easier to eat 100 g of fresh orange than fresh Moringa leaves.
- Vitamin A deficiency is prevalent in many developing countries and accounts for both maternal and child mortality. However, vitamin A deficiency is not an issue for the general population in the developed world, which undermines the value of Moringa for many of us.
Is There Any Research?
There are a total of 740 published papers on Moringa, but this includes just 5 human clinical studies. To put this into context, spirulina has twice as many papers and 50 human clinical trials.
Additionally, only 12 studies include genetic characterization of the Moringa species used.
Is Moringa an Anti-Inflammatory? Does It Have Antioxidant Properties?
There are no human clinical trials looking at the anti-inflammatory properties of Moringa. My PubMed search for clinical studies of the anti-inflammatory effects of Moringa did show a study in “cross-bred Xhosa lop-eared castrated goats.” If I ever have a “cross-bred Xhosa lop-eared castrated goat” join my practice, I will be sure to check that study. Seriously, who comes up with studies like that?
While there are no human clinical trials, there are a number of in vitro, in vivo, and ex vivo studies of interest.
Studies done in vitro show that Moringa leaves significantly decrease gene expression and production of inflammatory markers in macrophage white cells (2).
Another study identified a chitin-binding protein (Mo-CBP4) from M. oleifera seeds and showed that it exhibits anti-inflammatory and anti-nociceptive properties (3).
Moringa also contains kaempferol, which is emerging as an antioxidant/anti-inflammatory of interest (one to watch) in the medical literature (4).
An ex vivo study (cells taken from humans) showed that Moringa inhibited oxidative modification of human plasma cells (5).
Laboratory studies confirm the anti-inflammatory and antioxidant properties of Moringa, but this has yet to be replicated in human clinical trials.
Does It Balance Hormones?
A study from India found that Moringa leaf extract was beneficial in the reversal of hyperthyroidism in Swiss rats (6). Interestingly, the effect of Moringa was more pronounced in female rats and at lower doses (175 mg/kg versus 350 mg/kg). At this stage, it is hard to know the significance of these two findings, but it definitely suggests that there is a lot more to this story than just simple antithyroid effects.
Another study in rats showed that Moringa leaf exerted an antifertility effect in female rats, primarily by modulating the expression of estrogen and progesterone (7).
The fertility story does not end there. Sixty male Wistar rats participated in a study to look at the effects of mobile phone electromagnetic radiation-induced infertility (8). This study showed that testicular injury due to chronic exposure to electromagnetic radiation can be prevented by Moringa oleifera leaf extract.
Laboratory studies suggest that Moringa influences hormones, but it is very unclear as to what specific role Moringa plays. Much more research is needed to untangle the hormonal role of Moringa before it would be ready for human studies. Only then could recommendations be made on the hormonal effects of this tree.
Does It Slow the Effect of Ageing? Enhance Brain Health?
An experimental mouse model study showed that Moringa oleifera shows potent anti-inflammatory activity in the treatment of murine subacute Parkinson’s disease (9).
Another study relevant to Moringa and ageing comes from Thailand (10).
Yes, just another animal model of dementia, but interesting all the same. Rats with Parkinson’s induced by AF64A (a choline toxin) were given Moringa. Spatial memory was examined in a water maze. The rats were then sacrificed, and the brains were examined histologically.
This study demonstrated a memory-enhancing effect of M. oleifera leaf extract. It was thought that this might occur partly via decreased oxidative stress and also via enhanced cholinergic function. The authors concluded that the results suggest that M. oleifera leaf extract possesses the neuroprotective and memory-enhancing effects.
Finally, there is a growing interest in the use of Moringa for anti-ageing face creams (12).
Moringa is no more than a potential anti-ageing compound at this stage.
Does It Improve Digestive Health?
The science here is very limited again.
Moringa seed extract was shown to be effective in treating experimental colitis in male Wisteria rats (13).
As an aside, there is also interest in using Moringa gum as a carrier for colon-specific drug delivery (14).
There is no science to support the claim that Moringa improves digestive health.
Does It Affect Blood Sugar? Help With Diabetes?
Finally, we get a clinical study in real humans. A study in ten healthy volunteers in Thailand measured the insulin response to increasing doses of Moringa (14). There was a statistically significant reduction in the insulin secretion rate following 4 g of Moringa as compared to baseline.
It is worth noting that these volunteers were young, aged 29+/- 5 years, and had a low BMI of 20. As such, they are not representative of the demographic of the population of interest. It is also hard to rely too much on a study with a sample size of just 10.
There is a single healthy-volunteer study looking at the antidiabetic effects of Moringa. Further studies in patients with the metabolic syndrome+/diabetes are needed.
Is It Good for Your Skin?
There are two studies of interest here, in addition to the anti-ageing study mentioned above.
The first study from Pakistan enrolled 11 healthy volunteers aged 20-35 years old who applied a water-cream mixture of Moringa to their cheeks twice daily for 12 weeks. The study found that there was a significant improvement in skin hydration (15).
The second study from the same research group looked at 11 healthy volunteers who again applied Moringa cream twice daily to the cheeks for 3 months. Skin re-vitalizing parameters (surface, texture, and volume) and evaluation of living cells were done using skin topography. The study found a gradual decrease in roughness and scaliness, along with a gain in collagen (16).
Small short-term human clinical studies suggest that Moringa may be good for your skin. There are no large-scale, long-term studies to back this up.
Does It Stabilize Mood?
When it comes to mood disorders, most people think of anxiety and depression.
There are no studies of Moringa in anxiety.
There is a study of Moringa in a depressed mouse model (17).
Depressed Swiss albino mice were randomized to either a control group, low-dose Moringa +/- Prozac, or high-dose Moringa +/- Prozac.
The animals were tested using behavioral models of depression, such as forced swim test (FST), tail suspension test (TST), and locomotor activity test (LAT). The study suggested that low-dose Moringa extract plus 10mg Prozac positively affected the mood of these animals.
(The ethical part of me wonders if these depressed rats were given the successful Moringa plus Prozac cocktail (or maybe even some Toblerone) after the study ended.)
There are no human studies to support the mood-enhancing effects of Moringa.
Is Moringa Safe?
A number of clinically relevant side effects have been reported with Moringa.
Occupational asthma has been described with Moringa (18).
Moringa inhibits the activity of the cytochrome P450 3A4 system in the liver (19). This raises the possibility of clinically significant drug interactions with medications metabolized by this system, such as anti-HIV drugs, anti-TB drugs, and some BP medications. The leaves are more potent inhibitors of the cytochrome system as compared to the roots.
Moringa oleifera is safe at levels ≤ 1,000 mg/kg body weight but has been shown to be genotoxic at supra-supplementation levels of 3,000 mg/kg body weight (20).
The most comprehensive (44-page) review on Moringa published in 2015 in the International Journal of Molecular Science concluded that, “There are too few studies on humans to recommend Moringa leaves as medication in the prevention or treatment of diseases” (1). That about sums it up.
I feel a little guilty. I have enjoyed the shade of this beautiful tree and am now effectively “dissing” it. It feels especially bad as I read The Secret Lives of Trees on the plane ride here, which made a compelling case that trees are intelligent, sentient beings. So just in case and by way of apology, here goes:
Moringa exemplifies many of the problems with research on herbal medicines.
Firstly, there are relatively few studies to look at. This is unlikely to change, given the fact that producers of Moringa cannot use any positive results in their labeling or marketing. This is a major disincentive to funding any studies, and especially expensive human clinical studies.
Secondly, Moringa is not a single entity. There are 13 species of Moringa. Moringa is a tree with flowers, leaves, and seeds. That alone makes 39 variables of Moringa. Each part is a mixture of a huge range of compounds, each of which can have differing health or wellness effects. That makes for more “Moringas” than we could ever study or make claims about.
Finally, there is huge variability in the constituents of Moringa from place to place, season to season, and between producers, depending on their manufacturing practices. This comes down to the fact that there are no effective regulations to standardize herbal products such as Moringa.
Taken together, it is pretty meaningless to say that Moringa does anything.