by Michelle Lo, ND, and Melissa Cornish, HHC
Fruit is an important part of a healthy diet. Whether fresh, frozen, canned, or dried, the United States Department of Agriculture (USDA) recommends two servings of fruit per day, while the American Heart Association (AHA) recommends four servings per day. Your doctor or nutritionist may recommend more. Many popular diets, such as the Mediterranean diet and the anti-inflammatory diet, recommend nine servings of fruit and 15 servings of vegetables per day.
Fruit is high in fibre and low in sugar, is naturally filling, and contains many important vitamins and minerals. Berries tend to have the lowest sugar, while fruit such as grapes, mangos, navel oranges, and certain apples tend to have the most sugar.
A large-sized banana contains roughly 17 g of sugar, 3.5 g of fibre, and around 125 calories. It is a good source of potassium; B vitamins thiamine, riboflavin, B6, and niacin; folate; and vitamin C. Potassium is an important nutrient which supports heart health and kidney health. Bananas are also rich in beta-carotene, which is important for maintaining healthy eyes.
The vitamin B6 found in bananas helps maintain a healthy nervous system by supporting the production of neurotransmitters. Vitamin B6 is important for a healthy adrenal system, and it helps break down carbohydrates, fats, and protein for the body to utilize; it is also plays an important part in keeping the immune system strong, especially for older people.
Bananas are sweet and filling, they can help you recover from strenuous exercise, and they can help eliminate muscle cramps. The amino acid tryptophan, a precursor to serotonin, is found in bananas. Serotonin helps you feel calm, can lighten and regulate your mood, and can lessen your perception of pain. Bananas are a versatile food that can be used to combat both diarrhea and constipation, and act as a natural antacid.
In recent years, bananas have become reviled by some as a food that you absolutely can not eat if you want to lose weight or be thin. They have been blamed for causing weight gain, gas, and painful bloating.
Looking at Nutritional Facts
When choosing what food to eat, it is important to examine the nutritional information on the label. Along with the list of ingredients, you will find detailed information about how many calories, grams of carbohydrates, sugars, protein, and fat each serving contains. These are all important facts to know in assessing the potential health benefit or detriment of the food item. However, whole, unprocessed foods such as fruits, vegetables, and meats rarely have a nutrition label attached to them.
That’s not to say that the nutritional information of these foods is irrelevant or unimportant; what it means is that it is up to the consumer to seek out the information. This can be a good thing, if you know what to look for.
Carbohydrates v. Sugars
When it comes to our favorite fruits, most people would agree that they prefer fruit that is sweet to the taste. When you compare the number of grams of sugar in different types of fruit, you will see that there is quite a range of sugar content.
But there is a problem. Looking at the number of grams of sugar does not tell you whether those sugars are fructose, glucose, or sucrose; that is why nutritional labels also list carbohydrates. The term “carbohydrate” was developed to differentiate the effect the different types of sugar—simple or complex carbohydrates—has on our blood glucose level. Unfortunately, most labels aren’t specific about which type of carbohydrate it is listing.
Through clinical testing, it soon became apparent that carbohydrates do not affect the blood glucose level of all people in the same way. So, further testing was done on individuals to find a way to standardize a measurement of a food’s effect on blood glucose levels.
The Glycemic Index
During clinical testing, it was discovered that by testing a person’s blood glucose level after consuming 50 g of carbohydrate and comparing the results to an equivalent amount of pure glucose gave them a controlled standard to compare the person’s blood glucose level after eating a particular food. The lower the glycemic index (GI) rating, the less effect it has on blood glucose levels.
After plotting a curve of blood glucose levels taken before and several times after eating, plus some fancy calculations, the glycemic index became the new way to look at the health potential of food. Even the American Diabetes Association has adopted the glycemic index as their main tool for educating people on how to control their blood glucose level.
Let me give you an example why all of this, so far, is relevant. Let’s compare three popular fruits: watermelon, banana, and navel orange. One serving of watermelon has 18 g of sugar; one serving of banana has 17 g of sugar; and one serving of navel orange has 23 g of sugar. When comparing sugar content, the watermelon and banana look very similar.
When calculated on the glycemic index, watermelon has a GI rating of 76, which is equal to that of a donut; the banana, on the other hand, has a GI rating of 55, while the orange comes in last with a GI rating of 42. How is it that the fruit with the highest content of sugar (the orange) has the least effect on blood sugar? That has to do with the type of sugar and the amount of fibre these fruits contain.
Why Glycemic Load Is Better
The glycemic index is a little bit deceiving, because it is not based on testing done with the same serving size as outlined by the USDA. To make more relative sense of the data in the glycemic index, the glycemic load (GL) rating was developed. Glycemic load is a calculation based on the glycemic index rating and the USDA serving size, and it takes into consideration the amount of carbohydrates in one serving.
What the glycemic load tells us is how much we can expect one serving to affect our blood sugar when eaten on an empty stomach. A GL rating of ≥ 20 is high, 11–19 is intermediate, and ≤ 10 is low.
Interestingly, watermelon and oranges contain only 11 g of carbohydrates per serving, while bananas contain 24 g per serving. The GL of one serving of watermelon is 8, making it a good choice for those watching their blood glucose level. The GL of one serving of orange is 5, making it an excellent choice for diabetics and others with high-blood-sugar concerns. The GL for banana is 13, making it OK for most people, including diabetics, as long as other sources of sugar are kept low. One thing to keep in mind is that the more ripe a banana is, the more of its starch turns into sugar. A greener banana will have less of an effect on blood glucose levels than a very ripe one.
Let’s take a moment to recap what we know so far about bananas. Bananas are naturally sweet and are a good source of potassium, B vitamins, and vitamin C. They are fat-free, and a large-sized banana is about 125 calories. Due to 3.5 g of fibre and 24 g of carbohydrates, bananas are filling.
Now, let’s address the two opposing beliefs concerning weight. Regular consumption of bananas in addition to your regular diet can cause weight gain in those who are not physically active enough to burn them off. When they are eaten in place of other high-carbohydrate foods such as rice, pasta, bread, and most processed foods (including cereals), they will not cause weight gain.
If a banana is consumed with food that is high in protein and fat, the sugars in the banana are more slowly broken down and will have less of an effect on blood glucose, and you will feel full longer. You can add a banana to your high-protein breakfast or have it as a snack with nuts or a nut butter. Bananas are great for helping you recover from strenuous exercise, and the potassium can help relieve muscle cramps. Just remember to substitute the banana for other high-carb foods if you want to lose weight, or add them to your regular diet if you are needing to gain weight. Are bananas health food? Yes!
Gas and bloating from eating bananas can sometimes occur due to the high level of soluble and insoluble fibre. This should resolve itself once your body adjusts to the extra fibre, or you can take a daily probiotic to improve digestion. For someone who is not well-hydrated, the soluble fibre can cause minor constipation. In the case of diarrhea, the insoluble fibre will absorb water in the intestines helping to alleviate it.
If you have been diagnosed with or are being treated for diabetes type 1 or 2, HIV, cancer, heart failure, liver disease, kidney disease, lactic acidosis, metabolic acidosis, or diabetic ketoacidosis, it is important you talk to your doctor before adding bananas or extra potassium to your diet. Potassium can raise your blood pH level, which may help resolve acidosis, but you doctor may need to monitor your potassium blood serum level.