Green or ripe: how do you like your banana?

We usually eat bananas when they are yellow, that is when they start to ripe. Green bananas and yellow, ripe bananas have distinct health effects, that you may be interested to know.

Green banana for your gut

Unripe, green banana have the highest proportion of resistant starch, a form of carbohydrate that acts like a fiber. Green bananas contain prebiotics beneficial to gut bacteria. Green bananas have a lower glycaemic index, which means it takes longer to digest and triggers a lower, slower increase in blood sugar.

The drawback: they can be harder to digest and cause bloating.

Anti-oxidant yellow banana

Riper bananas are easier to digest, the starch is more rapidly converted into glucose and released into the bloodstream. On the other hand, the riper the banana, the higher the anti-oxidant content.

The drawback: with time, the content in vitamins and minerals decrease, to minimise that, you can store bananas in the fridge.

What exactly is the Mediterranean diet?

Perhaps you are reading this while in lockdown, and perhaps, just like me, you sometimes dream of holidays by the Mediterranean Sea… In my dreams, there are not only the blissful beaches bathed with crystal clear water, there is also the Mediterranean food: juicy tomatoes, plump aubergines, oriental meze, pasta of all shapes, a board of cheese and cured meat, and a glass of red wine. So much goodness!

And so many health benefits! The Mediterranean diet is associated with reduced risk of cardiovascular disease and cancer, improved cognitive health, positively impacts the immune function and inflammatory responses. What’s not to like?

Many studies have investigated the eating habits of populations living around the “Grande bleue” (Big blue sea) as we call her in France. Other studies have examined the effects of “Mediterranean diets” on health, in other populations. Truth is there are as many diets around the Mediterranean as there are countries, and the concept of « Mediterranean Diet » was invented in the 80’s in the US. Can we nevertheless draw a definition, or a description, of the celebrated Mediterranean diet?

Olive oil, a piacere!

One characteristic of the Mediterranean Diet resides in the extensive use of locally produced extra virgin olive oil (EVOO). Olive oil is very rich in monounsaturated fatty acids (MUFA, 73%), contains anti-inflammatory antioxidants and vitamin E (alpha tocopherol). Because it is the main source of fat in the Mediterranean diet and presents such a beneficial profile, olive oil is a key contributor to the healthy aspects of the Mediterranean diet.

Plenty of fruit and vegetables, nuts and pulses/legumes, a moderate protein intake

Traditional cuisine from countries around the Mediterranean include a wide variety of fruit and vegetables, from breakfast to dinner. Traditionally, cereals were often consumed wholegrain, therefore with an increased nutrient density. This allows a high content in fibre: on average, studies found that the Mediterranean Diet provides 30 to 35g of fibre per day.

Plant foods are also rich sources of folate, calcium, glutathione, antioxidants, vitamins E and C and minerals. Tomatoes, onions, garlic and herbs (oregano, mint, rosemary, parsley and dill) contain bio-protective nutrients such as carotenoids, flavonoids and polyphenols (antioxidants) and are widely used for cooking.

Nuts, consumed as a snack of incorporated in dishes bring additional healthy fats, vitamin E, magnesium, selenium and polyphenols. They contribute to maintain a healthy lipid profile.

Roughly 15% of the total energy intake comes from proteins. Red meat and eggs are consumed in small amounts and with low frequency; seafood intake varies, with moderate amounts of fish. Dairy foods are often in the form of cheese.

All minimally processed

Whatever the macronutrient balance, the “Mediterranean diet” is characterised by minimal processing of food items. This allows a maximum nutrient density.

Prebiotic, probiotic and synbiotic: who’s who?

A few definitions

Probiotics are « live microorganisms which when administered in adequate amounts confer a health benefit on the host », according to the FAO.
Probiotics supplements and additives contain a single or a mix of strains, the most commonly used being lactobacilles.

Prebiotics are nutrients that are degraded by gut microbiota. They feed the intestinal microbiota, and their degradation products are short-chain fatty acids that are released into blood circulation, consequently, affecting not only the gastrointestinal tracts but also distant organs.
Prebiotics are mostly fibers (for example inulin, pectin), which stimulate the growth and/or activity of gut bacteria. Prebiotics are present in natural products, but they may also be added to food.

Put simply, probiotics are live bacteria, and prebiotics are their preferred food.

Synbiotics are synergistic combinations of pro- and prebiotics.

What is the mechanism of action of probiotics and probiotics ?

Firstly, by promoting the growth of gut bacteria, probiotics contribute to the normal function of the organism. This effect is interesting to restore the microbiote after an antibiotic therapy. Secondly, probiotics could inhibit the development of pathogenic bacteria responsible for food poisoning.
Probiotics microorganisms not only naturally produce B group vitamins, they improve the absorption of other vitamin and mineral compounds and contribute to proper immune function.
Eventually, probiotics may be able to produce enzymes and show antibiotic, anti-cancerogenic, and immunosuppressive properties.

Prebiotics affect the composition of the intestinal microbiota and its metabolic activity. By doing so, they modulate lipid metabolism and the immune system, increase calcium absorption, and impact the bowel function, which confers a health benefit on the host.

Probiotics are essentially active in the small and large intestine, while the effect of prebiotics is observed mainly in the large intestine. Associating selected probiotics and prebiotics in the form of synbiotics may therefore enhance these effects.

Health benefits

Probiotics, probiotics and synbiotics have systemic effects on the host’s health metabolism and immune system. A recent review presents some of these benefits, which I list here.

  • increased satiety, which could help weight loss
  • anti-inflammatory and modulation of the immune system
  • increased absorption of minerals (bioavailability)
  • regulation of transit
  • improved gut health
  • prevention of cardio-vascular diseases

Food products rich in prebiotics and probiotics

Prebiotics are naturally occurring in fibre-rich foods such as: artichoke, asparagus, jerusalem artichoke, garlic, onion, leek, oats, kiwis, citrus fruits.

Probiotics are found in fermented foods such as: yogurt, kefir, kombucha, sauerkraut, pickles, miso, tempeh, kimchi, sourdough bread and blue cheeses.