Examine publishes rigorous, unbiased analysis of the latest and most important nutrition and supplementation studies each month, available to all Examine Members. Click here to learn more or log in.

In this article

I <3 green tea

When it comes to curbing cardiovascular disease, it’s not all about reducing cholesterol. Green tea may help prevent oxidation of LDL, as is explored in this trial looking at green tea catechins both in vivo and in vitro.

Study under review: Green tea catechins prevent lowdensity lipoprotein oxidation via their accumulation in low-density lipoprotein particles in humans


Atherosclerosis is a disease characterized by the thickening and narrowing of arterial walls due to the progressive buildup of plaque. Since atherosclerosis is a chief contributor to cardiovascular disease (CVD), the leading cause of death worldwide, there is great interest in finding ways to slow its development.

While the pathogenesis of atherosclerosis is only partially understood, mounting evidence[1] suggests that the oxidation of low-density lipoproteins (LDL) may play a pivotal role (as shown in Figure 1). Accordingly, protecting LDL from oxidation could potentially be a sound strategy in slowing its progression.

Figure 1: How oxidized LDL may contribute to athersclerosis

Adapted from: Stein et al.Int J Mol Sci. 2015.

A growing number of people are turning to dietary antioxidants to minimize oxidation. Lending credence to this trend, epidemiological[2] evidence[3] has displayed a positive association between use of dietary antioxidants and a reduced risk of coronary heart disease. This has been ostensibly corroborated by the results of animal studies[1] which indicate the effectiveness of antioxidants in reducing the severity of atherosclerosis. Although the few human trials[1] that exist remain equivocal, most used vitamin E or beta-carotene as their antioxidant. More clinical trials analyzing the effect of a wide range of antioxidants are needed to determine if antioxidants, either through food or supplementation, can help prevent or mitigate conditions like atherosclerosis.

Green tea is a popular beverage, in part due to its purported health benefits[4]. These health benefits may be attributed to green tea’s high concentration of polyphenols, which may have antioxidant properties[5] The major type of polyphenol found in green tea are known as catechins. The four main types of catechins are epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC), and epigallocatechin-3-gallate (EGCG). Researchers have proposed a molecular mechanism through which EGCG, the most abundant catechin in green tea, may reduce endothelial inflammation[6] by stimulating the cell’s own defense system against oxidants.

Moreover, the authors of the study under review previously found[7] that directly adding green tea catechins to isolated LDL particles inhibits oxidation in a test tube (in vitro). Although these findings are promising, what happens in test tubes doesn’t always replicate in humans. As a result, a few years later the authors extended their findings into humans[8], reporting that an acute intake of five grams of green tea powder led to an increase in plasma catechin levels and increased the resistance against LDL oxidation in healthy people. However, even though the increase in plasma catechin levels was simultaneous with a reduction in LDL oxidation, there was still a possibility that green tea protected LDL particles from oxidation through a mechanism unrelated to the catechins.

Therefore, the purpose of this study was to observe whether or not green tea catechins are incorporated into plasma LDL particles and thereby provide protection against LDL oxidation, both in vitro and in humans.

The oxidation of low-density lipoproteins (LDL) seems to play a pivotal part in the development of atherosclerosis, a chief contributor to cardiovascular disease (CVD). Recent studies have reported that green tea, which has a high concentration of antioxidants in the form of catechins, has the potential to reduce LDL oxidation. This study was designed to test green tea catechin incorporation into LDL particles, and hence protection against LDL oxidation.

Who and what was studied

Become an Examine Member to read the full article.

Becoming an Examine Member will keep you on the cutting edge of health research with access to in-depth analyses such as this article.

You also unlock a big picture view of 400+ supplements and 600+ health topics, as well as actionable study summaries delivered to you every month across 25 health categories.

Stop wasting time and energy — we make it easy for you to stay on top of nutrition research.

Try free for two weeks

Already a member? Please login to read this article.

What were the findings?

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

What does the study really tell us?

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

The big picture

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

Frequently Asked Questions

Become an Examine Member to unlock this article.

Already a member? Please login to read this article.

What should I know?

Become an Examine Member to unlock this article.

Free 2-week trial »

Already a member? Please login to read this article.

Other Articles in Issue #14 (December 2015)

  • Investigating vitamin D as a performance enhancer
    Having sufficient vitamin D levels has been associated with better muscle recovery. This trial not only looks at the question of causality, but also addresses some potential mechanisms of vitamin D’s benefit for exercise.
  • Trans fats: “natural” might not mean “healthy”
    In the nutrition community, a common message has been that artificial trans fats are bad, however natural trans fats are not only okay but beneficial. This trial on blood lipids puts that to the test.
  • High versus low fat diets for insulin sensitivity
    More body weight means more risk for metabolic syndrome. But the question of whether more fat (and especially saturated fat) impacts insulin sensitivity hasn’t been adequately addressed until now.
  • Exercise, with a (tart) cherry on top!
    Berries have burst onto the research scene in recent years. Tart cherries have shown some of the most promise in certain areas, leading to this study of powdered tart cherry on exercise recovery.
  • Interview: Dan Pardi MS PhD(c)
    Dan Pardi is an entrepreneur and researcher whose life’s work is centered on how to facilitate health behaviors in others.
  • Root rage: The impact of ashwagandha on muscle
    So called “adaptogens” like ashwagandha are typically studied for stress-easing potential. A randomized trial looked into this popular herb for a different purpose: bolstering adaptations to weight training.
  • Does the Food Guide make my butt get fat?
    By Francy Pillo-Blocka, RD
  • Antioxidants, anti-adaptations?
    We’ve covered antioxidants and strength training before. This study is a bit different — it investigates whether vitamin C and vitamin E might impact adaptations to endurance exercise.
  • Investigating slow carbs for metabolic rate
    Glycemic index, glycemic load, insulin index: only one of these is widely known by the public. But when it comes to keeping weight off, does glycemic index and total carb content actually have any impact?