Dr Oz Recommends THIS for Cholesterol

On one episode of his show, Dr. Oz invited Bryce Wylde, a popular homeopath, to discuss the different health benefits of artichoke. Bryce Wylde himself is the host of a show, Wylde on Health, as well as a doctor of homeopathic medicine.

Dr. Oz noted that artichoke was rich in dietary fiber and antioxidants which made the herb useful for a number of gastrointestinal problems ranging from indigestion to IBS (irritable bowel syndrome).

Besides its use in the treatment of gastrointestinal complaints, Dr. Oz also noted that a number of studies have established that artichoke can significantly lower cholesterol levels. So, what part of the artichoke is most useful and how does it reduce blood cholesterol?

Health Benefits of Artichoke

Artichoke or Cynara cardunculus var. scolymus is a vegetable native to the Mediterranean region including North Africa and Southern Europe. However, it is also now extensively grown in South America, the United States, and China.

Artichoke is commonly used in the preparation of certain dishes especially in Europe, North Africa, and the Middle East. Artichoke is also used to flavor liqueur and fruit juices especially in Italy and Switzerland.

As a food, artichoke has a high nutritional value. It is rich in dietary fiber, proteins, and micronutrients such as B vitamins, vitamin C, iron, calcium, magnesium, potassium, manganese, and zinc.

While the leaves are used in the preparation of food, artichoke flower is used to make a medicinal tea or tisane. This tisane is used in traditional medicine to cleanse the liver and as a diuretic.

The antioxidant property of artichoke is responsible for some of its major medicinal uses. In fact, artichoke has one of the highest antioxidant capacities among vegetables. Besides the antioxidants in artichoke, other artichoke phytochemicals of note are cynarin (inhibits the taste receptor to make drinks and foods taste sweet), luteolin and apigenin.

Different studies have established that artichoke improves digestive and liver functions. It also improves gall bladder functions.

In addition, available clinical evidence shows that artichoke can raise HDL (high-density lipoprotein or “good”) cholesterol while lowering LDL (low-protein lipoprotein or “bad”) cholesterol.

The hypocholesterolemic properties of artichoke involve the inhibition of the enzyme, HMG-CoA reductase. By lowering blood cholesterol levels and improving lipid profile, experts believe artichoke can reduce the risks of arteriosclerosis and coronary heart disease.

Artichoke Leaf Extract and Cholesterol

Although artichoke is an old remedy in traditional medicine, scientific support for its cholesterol-lowering ability has only recently been established.

One of the landmark studies on the subject (and the most frequently quoted) is a German study in which a group of volunteers were given 1,800 mg/day of artichoke extract for 6 weeks.

The results of the study showed that artichoke lowered total cholesterol levels by 18.5% (compared to 8.6% in the placebo group) and reduced LDL cholesterol by 22.9% (compared to 6.9% in the placebo group).

The study also found no serious adverse effect even with the high dose of the artichoke supplement.

With regards to HDL cholesterol, some studies found that artichoke does not affect the level of this “good” cholesterol while other studies found that artichoke can modestly raise HDL cholesterol. In addition, the effect of artichoke on triglycerides is only minimal.

Although experts believe that cynarin is the phytochemical in artichoke responsible for the herb’s cholesterol-lowering properties, recent evidence suggests that this is not the case.

Cynarin is also known as a hydroxycinnamic acid. It is believed to increase the production of bile in the liver and its secretion from the gallbladder.

Besides the two mechanisms of actions outlined above, artichoke can improve cardiovascular health in another way. Because of its high antioxidant content, artichoke can inhibit lipid peroxidation.

Basically LDL or low-density lipoprotein is only a container for cholesterol. It is responsible for transporting cholesterol through the blood. However, when reactive oxygen species and free radicals (like the ones released from the oxidation of lipids) oxidize LDL cholesterol, it turns “bad” and causes the thickening of artery walls.

Therefore, the antioxidants in artichoke can reduce the oxidation of LDL cholesterol and, therefore, improve cardiovascular health by a mechanism other than simply lowering cholesterol levels.

Studies on Artichoke and Cholesterol

Can Artichoke Lower Cholesterol Levels?

A 2008 study published in Phytomedicine: International Journal of Phytotherapy and Phytopharmacology, is only one of several studies done to investigate the cholesterol-lowering benefits of artichoke leaf extract.

For this study, the researchers recruited 75 adults with mild to moderate hypercholesterolemia and divided them into two groups.

While the first group was given a placebo, the second group received 1,280 mg of standardized artichoke leaf extract daily. After the 12-week duration of the study, the researchers found that plasma cholesterol levels were lowered in the artichoke group by an average of 4.2% while the placebo group experienced an increment of 2%.

This study found no differences in the levels of HDL cholesterol, LDL cholesterol, and triglycerides between the treatment group and the placebo group.

Even though this study did not find any evidence to support the LDL cholesterol-lowering effect of artichoke, other studies have confirmed that this vegetable can significantly reduce LDL cholesterol levels even more than the total cholesterol level. 

The researchers concluded that artichoke leaf extract can indeed reduce cholesterol levels. They also suggested that the positive health status of the volunteers may be responsible for the insignificant effect of artichoke on LDL cholesterol in this study.

It may well be that the variations in the composition of the various artichoke leaf extracts are responsible for the differences in the results of positive and negative studies.

The often-quoted 2000 German study on the effect of artichoke leaf extract on cholesterol levels was published in the journal, Arzneimittel-Forschung. This double-blind, randomized, placebo-controlled, multi-center study involved 143 adults with high cholesterol levels.

These volunteers were randomly assigned to the placebo and drug groups. Those receiving artichoke got a total daily dose of 1,800 mg dried artichoke extract supplied in the form of 450 mg tablets.

After the 6-week duration of the study, the volunteers receiving artichoke had significantly lower levels of total cholesterol and LDL cholesterol than those in the placebo group. In addition, the LDL/HDL ratio reduced by 20% in the artichoke group but only by 7% in the placebo group.

These results confirmed that artichoke can lower total cholesterol and LDL cholesterol levels. In addition, it may improve HDL cholesterol levels.

The researchers concluded that artichoke can be used in the treatment of hypercholesterolemia and also reduce the risks of arteriosclerosis and coronary heart disease.

How Does Artichoke Lower Cholesterol Levels?

A 2012 study published in the journal, Phytotherapy Research, provided great insight into how the actions of artichoke on bile acids lower cholesterol levels.

The researchers placed a group of 64 Golden Syrian hamsters on a control diet with or without 4.5 g/kg of artichoke leaf extract for 6 weeks. The study results showed that there was no difference in the levels of HDL cholesterol, non-HDL cholesterol, and triglycerides as well as fecal bile acids between the 2 groups of hamsters after 21 days.

However, after 42 days, the hamsters fed artichoke leaf extract had significantly lower levels of total cholesterol (15%), lower non-HDL cholesterol (30%) and triglycerides (29%).

Furthermore, the excretion of sterols (including cholesterol) and bile acids increased by 50% - 85%.

These results show that one of the important mechanisms by which artichoke leaf extract lowers cholesterol levels is by preventing the absorption of bile acids.

The body makes bile acids from cholesterol. On the other hand, bile acids are released into the intestine to prepare dietary fat (including cholesterol) for absorption. By preventing the reabsorption of bile acids into the systemic circulation, artichoke leaf extract encourages the body to keep on producing more bile acids from plasma cholesterol.

Therefore, artichoke can lower plasma cholesterol levels by increasing the fecal excretion of bile acids.

A 1998 study published in The Journal of Pharmacology and Experimental Therapeutics also revealed another mechanism by which artichoke can lower cholesterol levels.

The researchers injected high doses of aqueous extracts of artichoke leaf into cultured rat liver cells.

The researchers found out that artichoke leaf extract indirectly inhibits the enzyme, hydroxymethylglutaryl-CoA (HMG-CoA) reductase. This inhibition persisted for 20 hours after the artichoke extract was washed off and even blocked insulin from stimulating the enzyme.

Since HMG-CoA reductase is important for the body to synthesize cholesterol in the liver, this inhibition is an important mechanism by which artichoke reduces cholesterol levels.

Furthermore, the researchers determined that the active phytochemicals in artichoke responsible for this inhibition are cynaroside (a glucoside) and luteolin (an aglycone released from cynaroside).

Cynarin, once believed to be the phytochemical responsible for the inhibition, was found to have no effect.

Artichoke and Cardiovascular Health

In 2010, a group of researchers published the results of a study investigating the benefits of artichoke’s antioxidant and cholesterol-lowering activities in the journals, Phytochemical Research and Biological Trace Element Research.

The researchers fed a group of rats on a diet rich in cholesterol (4% w/w) and cholic acid (1%) for 1 month. During the last 2 weeks of the study, they added 1.5 g/kg/day of artichoke leaf extract to the diet.

At the end of the study, the researchers measured blood markers of oxidation, plasma antioxidant activities, and serum cholesterol levels.

The results of the study showed that the artichoke extract reduced total cholesterol and triglyceride levels and increased HDL cholesterol levels. In addition, artichoke reduced the markers of oxidation and increased plasma antioxidant activities.

These results indicate that besides lowering blood cholesterol levels and improving lipid profile, artichoke can reduce the oxidation of cholesterol (especially non-HDL cholesterol).

These benefits can significantly improve cardiovascular health and especially reduce the risks of arteriosclerosis and coronary heart disease.

Two Cochrane Reviews

Two Cochrane reviews have been done so far to determine the benefits of artichoke leaf extract in the treatment of hypercholesterolemia.

The first Cochrane review was done in 2002. The review only used the results of 2 randomized trials.

These trials involved a total of 167 participants. One of these studies reported a modest reduction in cholesterol levels with artichoke leaf extract while the other study reported a significant reduction.

The Cochrane review agreed that artichoke leaf extract can be used in hypercholesterolemia but called for more compelling evidence through more rigorous clinical trials involving larger study populations and longer study durations.

The second Cochrane review was done in 2009. This review used the results of only 3 randomized, controlled trials and the total number of participants in those studies was 262.

The reviewers agreed that all 3 studies showed that artichoke leaf extract significantly lowered cholesterol levels but still called for more clinical trials on the subject.

Both Cochrane reviews noted that artichoke leaf extract was safe and only produced mild, few and transient side effects.

Clearly, there are a lot more studies investigating the use of artichoke leaf extract in the treatment of hypercholesterolemia. However, Cochrane Reviews have strict and inflexible criteria for including studies in their reviews.

Even by this high standard, none of the studies used in both Cochrane reviews failed to confirm the cholesterol-lowering benefit of artichoke leaf extract.