Capers are one of the most concentrated plant sources of beneficial polyphenols, particularly quercetin and related flavonoids that support heart health, blood sugar control, and reduced inflammation. These tiny pickled flower buds pack a surprising nutritional punch for their size, and a growing body of clinical research suggests they offer real, measurable health benefits beyond just adding flavor to your pasta.
A Polyphenol Powerhouse
What makes capers stand out nutritionally isn’t their vitamin or mineral content per serving (they’re too small to eat in large quantities for that). It’s their extraordinary concentration of plant compounds called polyphenols. Fresh caper buds contain roughly 1,844 mg of total phenolic compounds per 100 grams of dry weight. The dominant ones are quercetin and kaempferol, two flavonoids extensively studied for their antioxidant and anti-inflammatory effects. Fermented (brined) capers retain much of this polyphenol content, though levels shift somewhat during the curing process.
These flavonoids work in part by blocking inflammatory signaling pathways in your cells, reducing the production of proteins that drive chronic inflammation. They also neutralize free radicals, unstable molecules that damage cells over time and contribute to aging and disease. Few foods deliver this density of protective compounds in such small portions.
Blood Sugar and Diabetes
One of the most promising areas of caper research involves blood sugar management. In a randomized, double-blind clinical trial of 54 people with type 2 diabetes, participants who took 400 mg of caper fruit extract three times daily for two months saw significant drops in both fasting blood sugar and HbA1c (a marker of long-term blood sugar control) compared to a placebo group. All participants continued their standard diabetes medications during the study, meaning the capers provided additional benefit on top of conventional treatment.
This doesn’t mean sprinkling capers on your chicken piccata will replace medication. The study used concentrated extract at consistent doses. But it does suggest that the compounds in capers have genuine glucose-lowering activity, likely related to their high flavonoid content.
Heart Health and Cholesterol
Capers also show real potential for cardiovascular health. A randomized clinical trial of 60 people with high cholesterol found that eating 40 to 50 grams of caper fruit daily alongside a standard cholesterol-lowering medication produced significantly greater reductions in total cholesterol and LDL (“bad”) cholesterol compared to taking the medication alone. The combination group also saw meaningful drops in triglycerides over the eight-week study period.
The effect was noticeable as early as four weeks. LDL reductions were already significantly greater in the caper group by the halfway point, suggesting the benefits accumulate quickly. These findings point to capers as a useful dietary addition for people already working to manage their cholesterol, though the study used larger daily amounts than most people typically eat.
Liver Protection
A systematic review and meta-analysis pulling together five clinical trials (178 adults total) found that caper fruit consumption reduced ALT, a key liver enzyme that rises when the liver is inflamed or damaged. The average reduction was about 12 units per liter, a clinically meaningful improvement. The studies included people with non-alcoholic fatty liver disease, type 2 diabetes, metabolic syndrome, and high cholesterol, with interventions lasting 2 to 12 weeks.
The review also found significant improvements in HDL (“good”) cholesterol and modest weight loss in caper-supplemented groups. For people concerned about liver health, particularly those with fatty liver disease, these early results are encouraging.
Anti-Inflammatory Effects
Chronic, low-grade inflammation underlies many common diseases, from heart disease to arthritis to certain cancers. The flavonoids in capers combat inflammation through multiple mechanisms. They inhibit the activity of a protein complex called NF-κB, one of the body’s master switches for turning on inflammatory genes. They also reduce production of cytokines (inflammatory signaling molecules) and C-reactive protein, a blood marker doctors use to assess systemic inflammation.
Researchers believe the anti-inflammatory power of capers comes not from any single compound but from the synergistic interaction of their flavonoids, phenolic acids, and other plant chemicals working together. This is one reason whole food sources often outperform isolated supplements.
Antimicrobial Properties
Caper extracts have demonstrated activity against several types of harmful microorganisms in laboratory studies. Ethanol-based caper extracts inhibited the growth of Candida albicans (a common fungal infection) and Streptococcus mutans (the primary bacterium responsible for tooth decay). Methanol extracts showed broader effects against various gram-negative bacteria and additional fungi. While these are lab findings rather than clinical trials, they help explain the traditional use of capers in folk medicine for infections and oral health.
Watch the Sodium
The biggest nutritional caveat with capers is their salt content. A single tablespoon of brined capers delivers about 16% of your recommended daily sodium intake. Salt-packed capers are even higher, closer to 21% per tablespoon. If you’re monitoring your sodium for blood pressure or heart health, this matters.
Rinsing capers before use removes a substantial portion of the surface salt. You can also soak them in cold water for 15 to 20 minutes, then drain and pat dry. This simple step lets you enjoy the flavor and health benefits without as much sodium baggage.
Caper Buds vs. Caperberries
The small, pea-sized capers you see in most grocery stores are flower buds, harvested before the plant blooms. Caperberries are the larger, olive-sized fruit that develops if the flower is allowed to open and pollinate. Each caperberry contains over a hundred tiny seeds that pop when chewed, giving them a texture nothing like the compact buds.
Both contain quercetin, kaempferol, and rutin as their primary beneficial compounds. However, research on fresh samples shows dramatically higher polyphenol concentrations in the buds compared to the berries. If you’re eating capers specifically for their health benefits, the small buds are the better choice. Caperberries are still nutritious, and they offer about 12% of your daily fiber per 100 grams, but they’re more of a snack or garnish than a polyphenol supplement.
Getting the Most From Capers
Because the key beneficial compounds in capers are flavonoids, and many flavonoids are better absorbed alongside dietary fat, pairing capers with olive oil, avocado, or fatty fish is a smart strategy. This is convenient, since most traditional caper recipes already involve olive oil. Think salmon with a lemon-caper sauce, or capers tossed into a salad with a good vinaigrette.
You don’t need to eat large quantities to benefit. Even a tablespoon or two added regularly to meals contributes meaningful amounts of protective polyphenols. The clinical studies used larger doses (concentrated extracts or 40 to 50 grams of caper fruit daily), but the consistent, smaller amounts typical in Mediterranean cooking are part of a dietary pattern already associated with lower rates of heart disease, diabetes, and chronic inflammation.