Bananas are one of the world’s most consumed fruits. Though they are a tropical fruit, bananas are available in even the smallest food stores in the northern hemisphere, far from their “roots”. Bananas are not usually considered to be a “superfood”, but you might be surprised about what they have to offer in healthy components.
The story of the banana is intriguing. Bananas come not from a tree, but from a large herb called Musa acuminata which is in the same family as the lily and the orchid. Bananas originated in the Indo-Malaysian region, a large territory that encompasses southern Asia and most of the islands between Asia and Australia. Rumours of the delicious yellow fruit had reached the Mediterranean region by the 3rd century BCE, but bananas did not actually arrive in Europe, carried in the holds of Portuguese ships, until the 10th century CE. Today bananas are grown in every humid tropical region worldwide and are the fourth largest fruit crop in the world, after grapes, citrus fruits and apples (1). Plantains, a larger variety of banana with a thicker skin, contain less sugar and more starch. They are generally edible only after cooking or when they are fully ripe.
Though there are hundreds of varieties of bananas, 99% of the bananas seen on the shelves of grocery stores in the developed world are of the Cavendish variety. Surprisingly, all Cavendish bananas stem from a single mutated plantain plant. This means that they are clones, with each banana genetically exactly the same as all the rest. Moreover, all these banana clones are sterile and can’t produce seeds. Each new plant must be cultivated from a cutting of existing banana roots (2,3).
Obviously this is a risky situation. Genetic uniformity makes the Cavendish banana more vulnerable to outside threats such as diseases and pests. On top of this, bananas are mono-cropped, which means they are grown on the same land year after year. This practice depletes the soil, increases the susceptibility of the banana crop to infections and allows easy spread of disease.
It was just such a threat that created the Cavendish banana monopoly. During the 1950s, a fungus swept through many banana fields causing widespread damage to the crop. The disease caused by the fungus was named Panama Disease. Amid worries of a repeat of this disaster, banana farmers turned to the Cavendish banana because it was naturally resistant to the fungus. In addition, Cavendish bananas stay green for several weeks after harvest making them ideal candidates for shipping long distances. Today, seventy years later, a new strain of the same fungus is slowly spreading throughout the banana-growing world. This one causes a novel form of Panama disease known as Tropical Race 4 (TR4). Alarmingly, there is no effective fungicide with which to fight it and the possibility that the beloved Cavendish banana could be wiped out within a few years is becoming a definite probability (2,3). On a positive note, the Honduras Foundation for Agriculture is three years into a project aimed at developing a disease-resistant banana variety as close as possible to the Cavendish. However, this process may take 15 to 20 years (4)
THE NUTRITION IN BANANAS:
Let’s put aside worries about future banana availability for now and enjoy them while we still can. Bananas are rich in a wide variety of beneficial nutrients.
One cup of mashed banana contains (5);
0.7 gm fat
2.5 gm protein
51 gm carbohydrate, including 6 gm fiber, 12 gm of starch and 27 gm of natural sugars
41% of the %DV for vitamin B6 (pyridoxine)
33% of the %DV for vitamin C
30% of the %DV for manganese
23% of the %DV for potassium
15% of the %DV for magnesium
11% of the %DV for folate
9% of the %DV for copper
8% of the %DV for Vitamin B5 (pantothenic acid)
7% of the %DV for vitamin B3 (niacin)
5% of the %DV for vitamin B1 (thiamine)
Note: %DV is the percent daily value and is calculated from the recommended daily intake and reference standards for nutrients. In a nutshell, the %DV is the percentage of the total amount of that nutrient required daily for good health.
Sugar Content of Bananas
Recently the internet has been rife with warnings regarding the high sugar content of bananas. One average-sized banana contains about 14 gm of sugar (5). As in all whole fruits, these natural sugars are bound up in the fibers that make up the structure of the plant. Since the plant structural components need to be broken down before the sugar can be released, not all of the sugar is absorbed and what does enter the bloodstream does so very slowly (7).
Glycemic index (GI) is a measure of how a specific food increases blood sugar levels. Foods are classified as low GI (55 or less); medium GI (56 to 69); or high GI (70 and above). The lower the GI, the less effect it will have on blood sugar level. Bananas are on the low side at a GI value of 42 to 62, with the higher GI levels in the ripest fruit (6). There is no need to worry that eating a banana will cause an unhealthy spike in blood sugar.
HEALTH BENEFITS OF BANANAS:
Bananas are among the most potassium-rich foods in our diets today. Eating enough potassium can help to keep blood pressure within the healthy zone. This may be because potassium helps protect against atherosclerosis and high blood pressure by softening the inner lining of blood vessels and increasing nitric oxide release (8,9). Nitric oxide is responsible for the proper functioning of the blood vessels including the prevention of inflammation and plaque build-up (10).
A study from 2014 showed that adding foods high in potassium (bananas and potatoes) to daily food intake significantly improved blood vessel function within one week compared to that of a control group eating daily apples and rice or pasta meals (11).
Research from 2011 reviewed eleven previous studies and found that higher potassium intake was associated with a 21% lower risk of stroke as well as reduced risks of coronary heart disease and total cardiovascular disease (12).
Bananas are also high in magnesium. Magnesium deficiency is associated with a number of chronic cardiovascular diseases, including hypertension, diabetes mellitus, and hyperlipidemia (13).
Observational data have shown an association between low blood magnesium level and increased atherosclerosis, coronary artery disease, arrhythmias and heart failure. However, supplementation with magnesium has shown inconsistent results along with adverse effects of too much magnesium. Nutritional studies are needed to elucidate the effect of dietary magnesium on the risk of cardiovascular disease (33).
Catechins, one of the flavanol-type antioxidants found in bananas, are linked to a reduced risk of cardiovascular disease (14).
Intake of resistant starch, which in bananas is found predominantly in unripe fruit and those with partially green skins, has been shown to improve insulin sensitivity and decrease the risk of both diabetes and cardiovascular disease (15).
Fiber and Resistant Starch
Bananas contain considerable amounts of prebiotics (fiber) and indigestible carbohydrates such as pectin and resistant starch. Resistant starch is most plentiful in green unripe bananas. It turns to sugar as bananas ripen. Pectin content also increases as bananas ripen.
Resistant starches and fiber reach the large bowel basically unchanged. These fiber types are the preferred food for beneficial bacterial species present in the gut microbiome which ferment them and produce short chain fatty acids. Short chain fatty acids promote a healthy gut lining and are linked to the suppression of inflammation and lower risk of cancers in the gut (for example, colorectal cancer) and some cancers in other organs (16,17).
A 2011 study found that participants with no gastrointestinal disease experienced less bloating and increased levels of bifidobacteria, a beneficial species of bacteria in the microbiome, after eating just one banana a day for sixty days compared to a controlled group eating no bananas (18).
Bananas may improve bone health through their potassium content. Many people do not obtain sufficient potassium in their daily diet and the addition of a banana or two a day can help increase potassium levels. Adequate dietary potassium has been shown to protect against age-related bone loss (19).
Protection Against Cancer
Bananas contain lectins, a group of proteins that protect plants from various invading organisms and other damage by binding to specific carbohydrates and counteracting the risk (20). The internet carries many stories of the dangers of lectins. However, these have been thoroughly debunked. Recent investigations into the effects of lectins on humans are revealing that they have mostly beneficial effects including limiting the growth of tumours, causing regression of cancers and inhibiting angiogenesis (the proliferation of new blood vessels that cancers require for their own growth) (21).
A study from 2014 examined the lectin in bananas specifically and reported that banana lectins exhibit the ability to suppress the spread of cancer cells (22).
Protection Against Chronic Diseases
Bananas are quite high in antioxidants. The peel and the pulp of both green and ripened bananas contain dopamine. Dopamine is an antioxidant similar in potency to vitamin C, one of the strongest known antioxidants (23). (Note that dietary dopamine does not cross the blood-brain barrier and so has no effect on mood or mental health.) Other antioxidants found in bananas are vitamin C, vitamin E, catechins (especially gallocatechin), phytosterols, flavonol-type antioxidants and phenolic compounds (24,25).
Antioxidants are important for reducing oxidative stress (inflammation) in the body. Free radicals are produced during normal cell metabolism and, if they are allowed to accumulate, cause oxidative stress.
Oxidative stress plays a major part in the development of chronic and degenerative illness such as cancer, autoimmune disorders, aging, cataracts, rheumatoid arthritis, cardiovascular disease and neurodegenerative diseases (26).
The human body can produce antioxidants but generally not in high enough amounts to cover antioxidant needs. This is where diet comes in. Epidemiological prospective studies show that higher intakes of antioxidant-rich fruits, vegetables and legumes are associated with a lower risk of chronic oxidative stress-related diseases such as cardiovascular diseases, cancer and deaths from all causes (27). Antioxidants in foods such as bananas can play an important role in reducing the risk of many chronic illnesses.
Diets rich in high potassium foods such as bananas seem to encourage better sleep. Research on people with lower blood potassium levels has found that these individuals suffer from disturbed sleep. Sleep impairment is associated with major health problems such as metabolic diseases (hypertension, type-2 diabetes), depression and cognitive impairment (28).
Tryptophan and Melatonin
Bananas are a good source of the amino acid tryptophan, a natural sedative. Studies have shown that consuming more tryptophan improves many measures of sleep. Tryptophan increases sleep efficiency, sleep time and immobile time and decreases total nocturnal activity, sleep fragmentation and time required to fall asleep. Total antioxidant capacity is also increased and anxiety and depression symptoms reduced with higher dietary intake of tryptophan (29).
Tryptophan is the precursor of serotonin (a relaxing neurotransmitter) and melatonin (a natural hormone produced in the body), both of which help to promote restful sleep. Melatonin is a regulator of circadian rhythms. It is produced from tryptophan, a process that increases when darkness falls and is stopped with light. In this way melatonin synchronizes the sleep-wake cycle with night and day and so facilitates easier transition into sleep and consistent quality of sleep (30). In our busy modern lives, melatonin production can be curtailed by staying up late.
Dietary melatonin from foods such as bananas can help promote healthful sleep. A 2013 study observed that eating tropical fruits including bananas can increase melatonin levels and raise antioxidant content in the blood (31).
Bananas are a good source of magnesium, known for its calming effects and links to increased sleep quality. Inadequate magnesium levels in the body are associated with insomnia as well as hypertension, diabetes, osteoporosis, migraines, premature ejaculation and premenstrual syndrome (32).
FINAL THOUGHTS ABOUT BANANAS
Bananas are a delicious and easy snack that is bursting with health-giving components and yet low in fat and sugar. Besides simply eating this fruit, bananas are also excellent for adding thickness to smoothies and sweetness to desserts. For an extra special treat, try using frozen bananas to create the following delicious plant-based frozen dessert.
Plant-Based Chocolate “Ice Dream”
Makes about 4 cups
½ cup soy milk
3 tbsp cocoa powder
1 tsp vanilla
3 heaping tbsp date paste (boil dates in a small amount of water for a couple of minutes then mash)
2 medium-sized bananas, frozen
1 cup frozen blueberries
Place soy milk, cocoa, vanilla and dates in a food processor or strong blender. Process until dates disappear. Add banana and blueberries and process until smooth. Eat immediately or freeze for future use.
7 Ludwig, D.S. Examining the Health Effects of Fructose. JAMA. 2013;310(1):33–34. doi:10.1001/jama.2013.6562
8 Oberleithner, H., Callies, C., Kusche-Vihrog, K., Schillers, H., Shahin, V., Riethmüller, C., Macgregor, G.A., de Wardener, H.E. Potassium softens vascular endothelium and increases nitric oxide release. Proc Natl Acad Sci U S A. 2009 Feb 24;106(8):2829-2834.
9 American Society of Nephrology. Low Potassium Linked To High Blood Pressure. ScienceDaily. November 2008. <www.sciencedaily.com/releases/2008/11/081109074611.htm>.
10 Deanfield, J.E., Halcox, J.P., Rabelink, T.J. Endothelial Function and Dysfunction. Contemporary Reviews in Cardiovascular Medicine. Circulation. 2007; 115:1285-1295
11 Blanch, N., Clifton, P.M., Petersen, K.S., Willoughby, S.R., Keogh, J.B. Effect of high potassium diet on endothelial function. Nutr Metab Cardiovasc Dis. 2014 Sep;24(9):983-989.
12 D’Elia, L., Barba, G., Cappuccio, F.P., Strazzullo, P. Potassium intake, stroke, and cardiovascular disease a meta-analysis of prospective studies. J Am Coll Cardiol. 2011 Mar 8; 57(10): 1210-12199. doi: 10.1016/j.jacc.2010.09.070.
13 Fox, C., Ramsoomair, D., Carter, C. Magnesium: its proven and potential clinical significance. South Med J. 2001 Dec;94(12):1195-201. PMID: 11811859.
14 Wang, X., Ouyang, Y.Y., Liu, J., Zhao, G. Flavonoid intake and risk of CVD: a systematic review and meta-analysis of prospective cohort studies. Br J Nutr. 2014 Jan 14; 111(1): 1-11. doi: 10.1017/S000711451300278X.
15 Johnston, K.L., Thomas, E.L., Bell, J.D., Frost, G.S., Robertson, M.D. Resistant starch improves insulin sensitivity in metabolic syndrome. Diabet. Med. 2010; 27: 391–397.
16 Bird, A.R., Brown, I.L., Topping, D.L. Starches, resistant starches, the gut microflora and human health. Curr Issues Intest Microbiol. 2000 Mar; 1(1): 25-37.
17 Sivaprakasama, S., Prasad, P.D., Singh, N. Benefits of short-chain fatty acids and their receptors in inflammation and carcinogenesis. Pharmacology & Therapeutics. August, 2016; 164: 144-151.
18 Mitsou, E.K., Kougia, E., Nomikos, T., Yannakoulia, M., Mountzouris, K.C., Kyriacou, A. Effect of banana consumption on faecal microbiota: a randomised, controlled trial. Anaerobe. 2011 Dec; 17(6): 384-387. doi: 10.1016/j.anaerobe.2011.03.018.
19 Weaver, C.M. Potassium and Health. Adv Nutr. 2013 May; 4(3): 368S–377S.
20 Lannoo, N., Van Damme, E.J.M. Lectin domains at the frontiers of plant defense. Front Plant Sci. 2014; 5: 397.
21 Abdullaev, F.I., de Mejia, E.G. Antitumor effect of plant lectins. Nat Toxins. 1997;5(4):157-163.
22 Singh, S.S., Devi, S.K., Ng2, T.B. Banana Lectin: A Brief Review. Molecules. 2014 Nov; 19(11): 18817–18827.
23 Kanazawa, K., Sakakibara, H. High content of dopamine, a strong antioxidant, in Cavendish banana. J Agric Food Chem. 2000 Mar;48(3):844-8. doi: 10.1021/jf9909860.
24 Someya, S., Yoshiki, Y., Okubo, K. Antioxidant compounds from bananas (Musa Cavendish). Elsevier Food Chemistry. November 2002; 79(3): 351-354.
25 AlAmri, F.S., Hossain, M.A. Comparison of total phenols, flavonoids and antioxidant potential of local and imported ripe bananas. Egyptian Journal of Basic and Applied Sciences. December 2018; 5(4): 245-251.
26 Pham-Huy, L.A., He, H., Pham-Huy, C. Free radicals, antioxidants in disease and health. Int J Biomed Sci. 2008 Jun; 4(2): 89-96.
27 Aune, D., Giovannucci, E., Boffetta, P., Fadnes, L.T., Keum, N., Norat, T., Greenwood, D.C., Riboli, E., Vatten, L.J., Tonstad, S. Fruit and vegetable intake and the risk of cardiovascular disease, total cancer and all-cause mortality—a systematic review and dose-response meta-analysis of prospective studies. International journal of epidemiology. 2017 Jun 1;46(3):1029-1056.
28 Heizhati, M., Zhang, Y., Shao, L., Wang, Y., Yao, X., Abulikemu, S. et al. Decreased serum potassium may disturb sleep homeostasis in essential hypertensives. Hypertension Research. Nov 16, 2018; 42: 174-181.
29 Bravo, R., Matito, S., Cubero, J., Paredes, S.D., Franco, L., Rivero, M., Rodríguez, A.B., Barriga, C. Tryptophan-enriched cereal intake improves nocturnal sleep, melatonin, serotonin, and total antioxidant capacity levels and mood in elderly humans. Age (Dordr). 2013 Aug; 35(4): 1277-1285. doi: 10.1007/s11357-012-9419-5.
31 Sae-Teaw, M., Johns, J., Johns, N.P., Subongkot, S. Serum melatonin levels and antioxidant capacities after consumption of pineapple, orange, or banana by healthy male volunteers. J Pineal Res. 2013 Aug; 55(1): 58-64. doi: 10.1111/jpi.12025.
32 Boomsma, D. The magic of magnesium. Int J Pharm Compd. Jul-Aug 2008; 12(4):306-309.
33 Tangvoraphonkchai, K., Davenport, A. Magnesium and Cardiovascular Disease. Advances in Chronic Kidney Disease. May, 2018; 25(3): 251-260.