Most of us think of orange juice as a simple breakfast habit, something you pour without much thought. Yet scientists are discovering that this everyday drink may be doing far more in the body than quenching thirst.

A recent study has shown that regular orange juice consumption can influence the activity of thousands of genes inside our immune cells. Many of these genes help control blood pressure, calm inflammation and manage the way the body processes sugar, all of which play an important role in long-term heart health.

The study followed adults who drank 500ml of pure pasteurised orange juice every day for two months. After 60 days, many genes associated with inflammation and higher blood pressure had become less active.

These included NAMPT, IL6, IL1B and NLRP3, which usually switch on when the body is under stress. Another gene known as SGK1, which affects the kidneys’ ability to hold onto sodium (salt), also became less active.

Such changes match previous findings that daily orange juice drinking can reduce blood pressure in young adults.

This is noteworthy because it offers a possible explanation for why orange juice has been linked to better heart health in several trials. The new work shows that the drink does not simply raise blood sugar. Instead, it appears to trigger small shifts in the body’s regulatory systems that reduce inflammation and help blood vessels relax.

Natural compounds in oranges, particularly hesperidin, a citrus flavonoid known for its antioxidant and anti-inflammatory effects, seem to influence processes related to high blood pressure, cholesterol balance and the way the body handles sugar.

The response also varies by body size. People carrying more weight tended to show greater changes in genes involved in fat metabolism, while leaner volunteers showed stronger effects on inflammation.

A systematic review of controlled trials involving 639 participants from 15 studies found that regular orange juice consumption lowered insulin resistance and blood cholesterol levels. Insulin resistance is a key feature of pre-diabetes, and high cholesterol is an established risk factor for heart disease.

Another analysis focusing on overweight and obese adults found small reductions in systolic blood pressure and increases in high density lipoprotein (HDL), often called the good cholesterol, after several weeks of daily orange juice consumption. Although these changes are modest, even slight improvements in blood pressure and cholesterol can make a meaningful difference when maintained over many years.

More clues come from studies that examine metabolites, the tiny molecules produced as the body processes food. A recent review found that orange juice influences pathways related to energy use, communication between cells and inflammation. It may also affect the gut microbiome, which is increasingly understood to play a role in heart health.

One study showed that drinking blood orange juice for a month increased the number of gut bacteria that produce short-chain fatty acids. These compounds help maintain healthy blood pressure and reduce inflammation. Volunteers also showed improved blood sugar control and lower levels of inflammatory markers.

People with metabolic syndrome, a cluster of risk factors that includes high blood pressure, raised blood sugar and excess body fat, may see particular benefits.

In one study, daily orange juice consumption improved the function of the lining of blood vessels, known as endothelial function, in 68 obese participants. Endothelial function describes how well blood vessels relax and widen, and better function is associated with a lower risk of heart attacks.

Not all studies report the same outcomes. A broader analysis of blood fat concentrations found that although levels of low density lipoprotein (LDL), often called the bad cholesterol, often fall, other lipid measurements such as triglycerides and HDL may not change much. Even so, people who regularly drink orange juice may still benefit.

A study of 129 workers in an orange juice factory in Brazil reported lower blood concentrations of apolipoprotein B, or apo-B, a marker that reflects the number of cholesterol-carrying particles linked to heart attack risk.

Altogether, the evidence challenges the idea that drinking citrus fruit juice is simply consuming sugar in a glass. Whole fruit remains the better choice because of its fibre, but a modest daily glass of pure orange juice appears to have effects that build up over time.

These include easing inflammation, supporting healthier blood flow and improving several blood markers linked to long-term heart health. It is a reminder that everyday foods can have more influence on the body than we might expect.

David C. Gaze, Senior Lecturer in Chemical Pathology, University of Westminster

This article is republished from The Conversation under a Creative Commons license. Read the original article.