What is really inside an olive?
“Olives are bad for you because they contain a lot of salt.” How many times have we heard this statement, or something similar? How many times have we resisted the temptation of a tasty olive at an aperitivo, out of fear it might raise our blood pressure?
It is certainly true that the sodium content of table olives is significant, but the idea that they are “bad for you” deserves closer examination. If we were to investigate further, the first thing we would discover is that not all table olives are the same: some contain more salt than others, depending on the processing method. It is important to note that olives contain a wealth of minerals, vitamins, antioxidants and other molecules that modern science recognises as beneficial to health.
In fact, some olives – those that are fermented and not pasteurised – are probiotic, just like the expensive jars and bottles of yoghurt found in supermarket refrigerated aisles. By the end of such an exploration, we would be quite surprised to conclude that table olives are actually a nutraceutical product, containing an even greater variety of beneficial compounds than extra virgin olive oil! All this, of course, provided they are consumed in moderation, as part of a healthy diet, precisely to limit sodium intake.
The alphabet of well-being
Let us begin our exploration in reverse alphabetical order, where the first letter we encounter is “V” for vitamins. Table olives are rich in tocopherols and tocotrienols. Of these, the most abundant is alpha-tocopherol, more commonly known as vitamin E. This vitamin is a powerful and relatively stable antioxidant. β-carotene, a precursor of vitamin A, is also present in green olives treated with lye or preserved naturally.
Next comes “P” for proteins. These essential compounds are present only in small amounts in olives – as in most plants other than legumes. However, the proteins in table olives have a high biological value, as they contain all the so-called essential amino acids.
“P” is also for polyphenols. Olives contain oleuropein, a complex molecule responsible for the extremely bitter taste experienced when eating olives straight from the tree, before processing. The various treatments olives undergo are designed precisely to transform this compound, making them palatable. From oleuropein, a number of other compounds are derived, in particular tyrosol, hydroxytyrosol and caffeic acid – all powerful antioxidants that neutralise free radicals, combating ageing and cellular degeneration. During fermentation, the microorganisms developed use part of these compounds, along with sugars, to create new ones, especially organic. Hydroxytyrosol is the most abundant phenolic compound found in the aqueous fraction of table olives.
Tyrosol is also present in high concentrations. The more olives are washed, the more the levels of these compounds drop. In the oily fraction, phenols are more numerous. However, in table olives – unlike extra virgin olive oil – the oily fraction represents on average only about 20% of the total, and thus a minority. The result is that the phenolic profile of table olives is far more complex and varied than that of extra virgin olive oil, and the overall quantity is also generally higher.
“M” for minerals. In addition to the obvious sodium content, other elements are also present. Most of these, with the exception of phosphorus and potassium, are found in higher proportions than in other vegetables. The calcium content of many table olives is comparable to that of milk, while their magnesium content is about three times as high. Iron and copper are present in more favourable proportions compared with other plant foods. The zinc content of olives is similar to that of onions, which are the vegetables richest in this mineral. The calcium-to-phosphorus ratio in table olives aids calcium absorption; the calcium-to-magnesium and potassium-to-magnesium ratios are comparable to those in other vegetables.
“F” for fibre. Table olives contain around 2% fibre, with a lignin-to-cellulose ratio below 0.5 – a figure indicating their good digestibility.
Finally, “A” for acid. This includes the long-chain fatty acids of triglycerides, also present in oil, which, being mostly monounsaturated (oleic acid), help control total cholesterol and low-density lipoprotein cholesterol (the infamous LDL). In table olives, however, there are also short-chain fatty acids. Unlike in oil, these are not eliminated during milling with the drupe water and added extraction water. Many are also formed during fermentation. These include primarily lactic and acetic acid in varying amounts, and in much smaller quantities, propionic and butyric acid. Their benefits to the human body are many:
- They promote the integrity of the intestinal barrier, reducing inflammation and helping prevent related disorders.
- They contribute to proper modulation of the immune system.
- They can positively influence the glucose and lipid metabolism.
Lactic acid, when ingested through fermented foods, helps create a favourable environment for beneficial gut bacteria and has mild antimicrobial properties against intestinal pathogens. It also increases the absorption of minerals such as calcium and iron. Acetic acid, meanwhile, can help lower blood sugar levels and improve insulin sensitivity, especially after carbohydrate-rich meals. It can stimulate gastric juice production, facilitating digestion and slowing gastric emptying. This can ultimately increase satiety, potentially reducing overall calorie intake. Some research indicates that acetic acid may also contribute to reducing cholesterol and triglyceride levels, and it has natural antibacterial properties.
In conclusion, organic acids such as acetic, propionic, lactic and butyric acid, in the amounts present, provide a wide range of health benefits – particularly for digestion, metabolism and immune function – and their synergistic action is greater than their individual effects.
But there are also other, perhaps less well-known acids that have long been studied for their nutraceutical potential: triterpenic acids. Olives are among the fruits richest in these compounds, containing 10, 100 or even 1000 times more than the most commonly eaten vegetables. Not all fruits and vegetables contain them in high amounts. Forgotten fruits like jujubes, or red fruits, are comparable sources. Another fruit relatively rich in these substances is the apple, the protagonist of the famous saying: “An apple a day keeps the doctor away”… The triterpenic acids in olives – oleanolic and maslinic acid – have recognised antioxidant, antimicrobial, anti-inflammatory, antitumour and anti-hyperglycaemic properties. There is just one drawback. If olives are poorly fermented and not brought to the correct pH level, most of these acids dissolve into the brine. This has led to ongoing studies and proposals to recover these valuable molecules from spent lye solutions, which, being alkaline, capture many of them. Nevertheless, even olives processed with the Sevillian method, that is, using caustic soda for debittering, retain significant amounts. By contrast, naturally fermented olives contain the highest levels. It is therefore essential to consume quality olives, produced properly according to best processing practices – not only for food safety reasons, but also for their nutritional benefits.
Conclusions
In conclusion, there is no doubt that, when eaten in moderation, table olives are indeed a nutraceutical food. They are certainly a snack a nutritionist would approve of – unlike the many products found in vending machines at offices and schools. And for those still worried about salt content, it is worth knowing that food research is already focused on refining production methods to preserve sensory and nutritional properties while reducing salt content by up to 50%.
So, there are no more excuses – apart from personal taste – not to enjoy a few table olives throughout the day. And given the wide variety of options – black, semi-ripe, green, natural, sweet, oven-baked, dried, wrinkled, oxidised, seasoned and countless others – it would be hard not to find something to suit everyone’s taste buds.
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