Olives and olive oil form a major part of the healthful Mediterranean diet that is now lauded the world over for protecting the heart and preventing cancer.1 But while olive oil has caught on as health food, olives still do not make it to a healthy diet. As whole fruits, however, an equal amount of raw olives has a higher amount of nutrients and antioxidants and less fat than olive oil, even the extra-virgin kind.
[pullquote]About 100 g of olives contains:
- 80 g water, 116 calories
- 10.9 g fat, of which 7.652 g is monounsaturated fat, including oleic acid
- 5% fiber
- 8.8% calcium
- 34%–77% iron
- 31.9% sodium
- 10.6% vitamin E
- A tiny amount of protein, zinc, vitamin A, and vitamin K2
- Over 30 antioxidants, including oleuropein, hydroxytyrosol, tyrosol, oleonalic acid, maslinic acid, and oleocanthal3[/pullquote]
The reason table olives have not caught on is that excluding some varieties, most raw olives are too bitter, thanks to the antioxidant oleuropein. Olives can be made edible only after curing or debittering them in water, brine, dry salt, or commercially, with lye (sodium hydroxide). The olives you find in supermarkets, farmers’ markets, and olive bars are all processed. Some of the curing processes rob the olives of the antioxidants (including oleuropein), add a lot of sodium, and make portion control necessary.
But even when eaten in moderation, table olives can give you the following health benefits. Do note that most studies have been conducted on extra-virgin olive oil or olive extract rather than whole olives, but since extra-virgin oil is cold-pressed from the fruit and retains most of its phenolic content, the benefits are comparable.
1. Balance Cholesterol Levels
Scientists held for long that a high HDL and a low LDL cholesterol level indicates a healthy heart. However, modern research suggests that your heart health does not depend on how high your HDL levels are but on how efficient these “good cholesterols” are.4 This is where olives and olive oil could be helpful.
A new study has found that extra-virgin olive oil, cold-pressed from olives, does not alter the LDL or HDL levels but protects HDL cholesterol from oxidation and enhances its functioning.5 Better-functioning HDLs translates to efficient removal of LDLs from the body.
This benefit is due to the healthy monounsaturated fats as well as the olive polyphenols. Hydroxytyrosol in particular helps prevent the oxidation of LDL cholesterol and thereby atherosclerosis, a major risk factor for heart disease.6 Oleuropein changes to hydroxytyrosol as the fruit matures. This is why tree-ripe olives are less bitter than the unripe ones.7 And while the debittering process removes much of the oleuropein, the hydroxytyrosol levels remain high.
2. Lower Blood Pressure
The Unites States Food and Drugs Administration recommends substituting saturated fat with 2 tablespoons of extra-virgin olive oil a day while keeping the calorie intake constant to cut the risk of heart disease.8 Several studies on healthy subjects as well as those with high blood pressure have found that extra-virgin olive oil can reduce blood pressure, especially systolic pressure, thanks to the polyphenols.9 Oleuropein and hydroxytyrosol improve blood vessel function and blood circulation. They also prevent platelet aggregation, which reduces the risk of blood clots suddenly blocking blood vessels and causing strokes.10 11 12
Two tablespoons of extra-virgin olive oil would equal about 30 g or 10 small canned olives. However, these would give you negligible oleuropein and 235 mg of sodium, which is 15% of the recommended sodium intake for a patient of high blood pressure. In this case, choose naturally sweet tree-ripe olives like the Turkish Hurma and the Greek Trubolea or varieties which have a high oleuropein content even after curing, such as Thruba Thassos.
3. Manage Diabetes
Olives have a beneficial effect on diabetes. Traditional Greco-Arab medicine recommended olive leaves to control blood glucose levels in diabetics, and modern dietary guidelines for diabetes management also suggest olive oil.13 14 As per a 2017 study, this glucose-lowering effect of olives is due to oleuropein, the bitter antioxidant compound found in the olive leaf as well as the fruit. It helps the body secrete more insulin, which is necessary for glucose metabolism. It also regulates the production of amylin, another hormone, which when overproduced forms clumps and leads to type 2 diabetes.15 Hydroxytyrosol too also been found to lower blood glucose levels in an animal study.16
If you are not daunted by the bitterness, try water-cured olives since water curing does not leach out the oleuropein fully. You may also opt for naturally ripe black olives, such as Kalamata olives, which contain a high amount of hydroxytyrosol.
4. Prevent Osteoporosis
It’s a known fact that people in the Mediterranean regions do not suffer from bone loss or osteoporosis as much as the rest of the world. And besides the other calcium-rich leafy greens, olives could be the reason. In animal studies, the olive polyphenols oleuropein and hydroxytyrosol improved calcium deposition and prevented the formation of osteoclasts, the cells involved in the breakdown of bone tissue.17 18 Since hydroxytyrosol has a more potent effect in bone formation and maintenance, naturally ripe black olives are better than the green ones.
5. May Prevent Anemia
Black olives are a rich source of iron. A 100 g serving of canned olives meets about 34% of your daily need for iron if you are female (19–50 years) and about 77% if you are male. Iron is essential for many vital functions in the body, the chief among which is the production of red blood cells and transportation of oxygen. Lack of iron results in anemia, which can be life-threatening for pregnant women. While 100 g olives is a lot more than you should consume in a day, having a few a day can contribute to your total iron intake.
6. Prevent Ulcers
[pullquote]One study has found that the antioxidants in olives may fight bacterial infections in the body’s airways.19[/pullquote]
Virgin olive oil has a beneficial effect on ulcers in the esophagus and stomach caused by the H. pylori bacteria. In one lab study, the polyphenols in virgin olive oil, chiefly oleocanthal (also known as decarboxy methyl ligstroside aglycone), could kill 8 strains of the bacteria, 3 among which were antibiotic-resistant. While human studies have not been conducted, what’s heartening is that compared to polyphenols from tea, wine, or plant extracts, a lower amount of olive polyphenols was required to kill the bacteria.20 So one could say that having olives and olive oil in dietary amounts could prevent peptic and gastric ulcers.
7. Relieve Pain In Arthritis
[pullquote]Oleocanthal is what gives the pungency to virgin olive oil, and oils with greater pungency are rightly considered superior.[/pullquote]
Given that olives are so rich in antioxidants, their anti-inflammatory benefits are guaranteed. In fact, oleocanthal is similar in function to the pain-relieving drug ibuprofen. It inhibits the function of an inflammation-triggering enzyme called COX and reduces the levels of inflammatory proteins. This is why olive oil is recommended to patients of arthritis and rheumatoid arthritis.21 A few small-scale, short-term human studies conducted with olive extract, hydroxytyrosol, and virgin olive oil on patients of osteoarthritis have also reported some improvement in pain and symptoms.22 23
8. May Prevent Neurodegenerative Diseases
The anti-inflammatory benefits of oleocanthal and the other polyphenols in olives extend to the brain and nerves as well. In patients of dementia, two proteins called tau and beta-amyloid form clumps inside the neurons and outside brain cells, respectively. Oleocanthal can prevent the clumping of tau proteins and also clear up the beta-amyloid clumps.24 However, these studies have been conducted on animals using oleocanthal in amounts larger than can be found in dietary amounts of olive oil or olives. It’s also not known how well the body absorbs it and keeps it in circulation. More studies are required to understand how we could get these health benefits in a sustainable and realistic way.
9. Prevent Allergies
Olives and olive leaves have been used traditionally to combat inflammatory conditions, including allergies. In one study, hydroxytyrosol in olives suppressed the immune reaction of healthy cells to the pollen of pellitory of the wall, a highly potent allergen.25 So it seems that having naturally ripe olives regularly could protect you from seasonal allergies.
10. Promote Youthful Skin And Hair
Olives may also give you youthful skin and hair. Like most antioxidant-rich foods, olives also fight free radical damage. Oleuropein, hydroxytyrosol, and squalene have been found to protect the skin against UV light and radiation. Olive leaf extracts also show preventative effects against chronic UVB-induced skin damage.26 However, applying olive oil directly on your skin may have a more pronounced effect than eating the fruits.
11. Have Anti-Cancer Properties
At the moment, no research has been conducted on the benefits of whole olives for cancer. But the lower rates of cancer among people consuming the Mediterranean diet suggest that olives may have a role to play. Theoretically, olives can keep cancer at bay as they contain up to 16 grams/kg of important cancer-fighting agents like acteoside, hydroxytyrosol, tyrosol, and phenyl propionic acids.27 Isolated chemicals, such as the oleuropein in olive leaf extract or hydroxytyrosol from the fruit have been found to induce cell death in breast, prostate, colon, papillary, and thyroid cancer cells without affecting healthy cells.28 29 30 We need more research to understand whether olives could cure cancer as well.
Which Olives Should You Choose?
The health benefits of commercial table olives depend on the cultivar, stage of ripeness, and the debittering process. There are essentially 3 types of table olives: Spanish-style green olives, Greek-style natural black olives, and California-style black olives. Both the Spanish- and California-style olives involve processing with lye, followed by thorough washing and brining. The California style of processing also involves oxidation, while the Spanish style involves fermentation. As a result, the antioxidant quotient of these olives is quite low. However, the Spanish-style may have an edge over the California-style, thanks to their probiotic benefits.
[pullquote]The California-style black olives you find sliced up on your pizza are not naturally black. They turn black during processing. The Kalamata olives from Greece are, however, naturally black or dark brown and are considered the healthiest.31 32[/pullquote]
On the other hand, since the Greek style of processing involves no chemicals and just brining or dry salt curing for several months, Greek-style olives like the black Kalamata and Tsakistes retain more antioxidants. While most olives have been found to contain varied amounts of hydroxytyrosol, depending on the cultivar and the debittering process, the Greek salt-cured Throuba Thassos also contains oleuropein and can be more helpful.33
If you can, get hold of naturally sweet varieties like the Turkish Hurma and the Greek Thrubolea.34
How To Buy Olives
If you buy your olives from an olive bar, don’t choose those that have mold or are dry. Make sure the liquid in the olive jar is clear. Olives tend to be easily infected by fungus, so make sure you preserve the olives in brine, that is salt solution even at home. The California-style ripe olives also have a harmful compound called acrylamide formed during processing.35 So if you have a choice, opt for Spanish-style olives which have undergone fermentation or the naturally cured Greek ones.
Do remember that while canned green olives do contain more vitamins, minerals (except iron), and fat than canned black olives, they contain about twice the sodium.36 Stick to no more than 10 olives a day so as to not exceed your recommended daily sodium intake.
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