Banana contains plentiful potassium ions, dietary fiber, vitamins, and antioxidants. Delicious and nutritious, bananas are not only healthy snacks, but also great for preventing cancer, cardiovascular diseases, memory decline, and relieving anxiety.
What can a banana a day do for the human body?
1. Cancer Prevention
In a research report published in the International Journal of Cancer in January 2005, researchers at the Karolinska Institute in Sweden conducted a 13.4-year study of 61,000 women aged between 40 and 76.
The study found that women who ate at least four bananas a week lowered the risk of kidney cancer by 50 percent.
Women who eat root vegetables such as carrots and beets also have a lower incidence of kidney cancer.
A Japanese study (pdf) discovered that ripe bananas can boost human immune cells to produce tumor necrosis factor (TNF), which can fight abnormal cells.
The darker the patches on the banana skin, the better the immune system enhancement. Yellow-skinned bananas with dark spots have eight times the ability to increase white blood cells than green-skinned bananas.
Bananas also contain substances that have the potential to develop anti-cancer drugs.
A research review published in Frontiers in Oncology in 2021 wrote that the extracts of banana fruits and banana plants show prevention and anti-cancer activities for various types of cancer by regulating different cell signal conduction pathways. The botanical chemicals in bananas can be used to develop multitarget drugs for cancer treatment.
2. Cardiovascular and Cerebrovascular Disease Prevention
Bananas are rich in magnesium. Magnesium helps reduce the risk of atherosclerosis by lessening the plasma oxidized low-density lipoprotein, also known as bad cholesterol. They also have a lot of potassium, which controls blood pressure and regulates heart rate.
The human body is prone to arrhythmias and elevated blood pressure when it lacks potassium. The right amount of potassium can stabilize the excitability of nerves and muscle cells within the normal range, maintaining the heart’s proper functioning.
In a research report published in the European Heart Journal in 2022, the research team conducted a 19.5-year study of 24,963 participants, a total of 11,267 men and 13,696 women.
The results revealed that compared to those with the lowest potassium intake, the risk of cardiovascular disease was drastically reduced by 13 percent in those with the highest potassium intake.
Cardiovascular disease onset or recurrence risk was 11 percent lower in women and 7 percent in men.
The research indicated that eating more potassium-rich foods can prevent heart disease and stroke, especially for women.
In addition to potassium, bananas contain a lot of water-soluble dietary fiber, which is essential for heart disease prevention.
A study published in JAMA Internal Medicine in 2003 confirmed that eating high-fiber foods such as bananas can prevent heart disease. Over 9,700 American adults participated in the study. During the years of follow-up, researchers discovered participants’ risk of coronary heart disease (CHD) and cardiovascular disease (CVD) was reduced by 12 percent and 11 percent, respectively, in those who consumed the most fiber per day at a median of 20.7 grams, and those who ate the least water-soluble fiber daily at a median of 5.9 grams.
People with the highest daily consumption of water-soluble fibers, at a median of 5.9 grams, compared with the lowest median of 0.9 grams, also saw a decreased risk of heart disease by 15 percent. The mortality rate of coronary heart disease was reduced by 24 percent, while the chance of getting heart disease went down by 15 percent.
This particular group of participants was also 10 percent less likely to develop cardiovascular disease, with cardiovascular disease mortality rates also dropping by 12 percent.
3. Memory Loss Prevention
Bananas are a fantastic source of vitamin B6. Vitamin B6 regulates the homocysteine level in the blood, thus improving cognitive ability.
In a study published in The American Journal of Clinical Nutrition in March 1996, researchers at Tufts University in Boston conducted cognitive tests on 70 men aged between 54 and 81.
They found that subjects with higher vitamin B6 levels performed better in two memory tests.
Research shows (pdf) that eating fruits rich in potassium, such as bananas, helps students improve concentration and study more effectively, thus, improving their test scores.
A school in Twickenham (Middlesex), England, helped 200 students to pass the exam by giving them bananas at breakfast, break, and lunch to improve their brain power.
4. Emotional Regulation, Anxiety, and Depression Relief
Bananas contain tryptophan, which the human body can convert into serotonin. Serotonin can relax the body, relieve anxiety, and make people feel joy.
Bananas also contain B vitamins, which play a vital role in the human nervous system, as coenzymes coordinate chemical reactions in the body.
A study published in the journal Human Psychopharmacology: Clinical & Experimental in 2022 documented that researchers at the University of Reading measured the effect of high doses of vitamin B6 on 478 participants.
The clinical study found that high doses of vitamin B6 consumption can reduce anxiety and depression.
Another study published in the Pakistan Journal of Pharmaceutical Sciences in 2017 pointed out that banana pulp and peel have anti-anxiety, anti-depression, and memory-enhancing functions, likely due to their antioxidant effects.
Some People Should Avoid Overeating Bananas
Patients with Kidney Disease
Since the potassium content in bananas is high, the metabolic function of potassium is abnormal in patients with acute and chronic nephritis, renal insufficiency, and other kidney diseases if consumed too much.
Hyperkalemia and symptoms such as muscle weakness, drowsiness, and slow heart rate may arise.
Therefore, the National Kidney Disease Foundation suggests that patients with kidney disease avoid bananas and have apples instead.
The sugar content of bananas is high. People with diabetes should be mindful of the amount they eat.
According to the U.S. Department of Agriculture Nutrition Database, 100 grams of bananas contain about 15.8 grams of sugar.
However, since bananas contain more fiber and resistant starch that the human body cannot absorb, their glycemic index (GI) is not high, so it will not cause a sharp spike in blood sugar.
According to the School of Public Health of Harvard University, the glycemic index of ripe bananas is 51. While the glycemic index of semi-ripe bananas is only 42, it is still higher than that of apples, with a glycemic index of about 36.