Grape Seed Extract with Vitamin C: A New Duo for Cardiovascular Health

We hear about cardiovascular health all the time. And for good reason. Your cardiovascular system delivers oxygen, nutrients, hormones, and more to all the cells, tissues, and organs of the body. Supporting the health of this central body system is vital for longevity.

Scientists at USANA partnered with researchers at Boston University to find out if there was a way to support cardiovascular health by protecting against oxidative stress in the blood vessels. Their hypothesis was that two powerful antioxidants, epicatechin (found in Grape Seed Extract) and Vitamin C, could support blood flow and provide antioxidant protection. In this study, the results showed that when taken together, these two ingredients did support markers of cardiovascular health.

Summary of Study Findings

  • 42 participants
  • The treatment included 450mg of Grape Seed Extract and 1500mg of Vitamin C daily for four weeks.
  • Blood samples and vascular tests were conducted two and four hours after day-1 treatment and again two and four hours after treatment on the last day.
  • Treatment significantly increased antioxidant levels, serum vitamin C, and plasma epicatechin at all time points.
  • Acute treatment helped optimize blood flow in the peripheral blood vessels (capillaries and arterials)

The scientists concluded that GSE and Vitamin C have a complementary relationship in supporting vascular health. Together, these ingredients support antioxidant protection, help maintain the function of the blood vessels, and optimize blood flow.

The design and hypothesis of this study were based on the root of cardiovascular health, according to scientific literature. Like with all the other body systems, health starts in the cell. One of the biggest threats to a healthy cell is something called oxidative stress. This kind of stress is caused by reactive molecules called free radicals, which your body produces constantly. They’re the byproducts of being alive. When the body can’t detoxify these reactive molecules quickly enough, they accumulate in the cell and cause damage. This can happen to all cells, including those that make up your blood vessels.

The Cells Behind Your Cardiovascular Health

There is a layer of cells on the inside of your blood vessels (arteries, veins, and capillaries) called the endothelium. In fact, this continuous layer of cells is one of the largest organ systems in the body.

These cells are crucial to cardiovascular health. Their job is to keep your blood vessels open (or dilated), which keeps your blood pressure normal and your heart happy. Flexible blood vessels are a critical factor in maintaining the health of the heart and the whole cardiovascular system.

To understand how the endothelial cells accomplish this, we need to zoom in even more. Down to the chemical level.

Scientists don’t know the exact mechanism behind endothelial function, but they know it’s related to Nitric Oxide (NO). If you’re familiar with the fitness industry, you’ve probably heard of NO. Pre-workout products that claim to increase blood flow and improve performance all aim to increase NO levels. NO is also produced in the body, by your endothelial cells. They activate NO to keep the blood vessels open. So, it makes sense that scientists say supporting NO production is crucial for proper endothelial function.

You might be wondering, why would NO activity slow down? Let’s circle back to oxidative stress. Research has shown that when oxidative stress builds up in the endothelial cells, it reduces the production and function of NO.

To summarize. Cardiovascular health is supported by endothelial function. Healthy endothelial cells require NO to do their job. The loss of NO can be linked to the accumulation of free radicals in the cells.

We also know that antioxidant levels determine how well your body can neutralize free radicals. This suggests that supporting the body’s antioxidant potential could be a way to support cardiovascular health.

That’s exactly what USANA scientists wanted to test. They proposed that vitamin C and grapeseed extract would support antioxidant levels in the blood, which would help maintain the health of the endothelium.

Vascular Health Study

The researchers conducted a double-blind, placebo-controlled study to see if this combination of antioxidants could help optimize markers of vascular health.

A variety of antioxidants have been studied in the past for their cardioprotective properties. But the scientists chose these two based on their cardioprotective potential.

Vitamin C (ascorbic acid)

Did you know that Vitamin C is an antioxidant? One of the most powerful in fact. Many of Vitamin C’s most well-known health benefits come from its antioxidant properties. Research also suggests that Vitamin C supports the dilation of blood vessels.

Grape Seed Extract (GSE)

The seeds of grapes contain many beneficial flavonoids, like epicatechin. This flavonoid is known for its antioxidant and cardiovascular benefits.

42 patients were involved in the study. Half the group was given the treatment (Vitamin C and GSE supplement), while the other half received the placebo. After 4 weeks, the groups switched and were given the opposite treatment for another 4 weeks.


The study produced important findings. Overall, the researchers concluded that this specific combination of GSE and Vitamin C helped support antioxidant levels and endothelial function. Specifically, it supported the function of the endothelium in the smaller blood vessels (capillaries and arterials).

They also found that antioxidant reserves in the body increased with the treatment. Vitamin C and epicatechin levels in the bloodstream also increased following treatment.

Altogether, the results suggest that GSE and Vitamin C complement each other in supporting markers of cardiovascular health.

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