Turmeric and Cholesterol
Turmeric is a spice related to ginger. It is notable for its curcumin content. Curcumin is a food additive that impacts a deep orange-yellow color to foods. Besides its culinary uses, turmeric is also a potent, well-studied herb with numerous proven medicinal uses. Studies have shown that turmeric can lower blood cholesterol. How does turmeric and curcumin affect cholesterol levels and how can you use the spice to treat hypercholesterolemia? Read on to find out.
by Brad Chase
Turmeric or Curcuma longa belongs in the ginger family. It is perennial plant native to South Asia and known for its rhizome which has a long history in food preparation and traditional medicine.
Although fresh rhizome is the most common form in which turmeric is used as food and medicine, turmeric powder is also used as dye and food coloring because of its deep orange-yellow color.
The culinary uses of turmeric extend beyond simply serving as a food additive to impact its bright orange-yellow color, it also serves as a spice in curries and as condiment.
The most popular bioactive compound in turmeric is curcumin. This is the compound responsible for the bright color of the herb and as a food additive, it is known as E100. Curcumin is also responsible for most of the medicinal properties of turmeric.
Turmeric has been used for centuries in both Ayurveda and Chinese traditional systems of medicine. This spice is used as a herbal remedy in the treatment of colic, jaundice, hemorrhage, toothache, chest pain and blood urine.
Research into the therapeutic properties of the phytochemicals in turmeric has been growing in recent years. As at 2012, over 70 clinical trials have been registered with the U.S. National Institutes of Health investigating the health benefits of curcumin and turmeric.
These new studies show that the phytochemicals in turmeric have potent antioxidant and anti-inflammatory properties. Turmeric also has antibacterial and antiviral activities.
These medicinal properties have been shown to be useful in the treatment of inflammatory bowel disease, cystic fibrosis and rheumatoid arthritis.
However, one of the major areas of turmeric research involves the usefulness of the herb in the prevention and treatment of certain cancers. Preliminary studies indicate that turmeric can reduce the risks of prostate, breast, colon and lung cancers.
In addition, turmeric has been shown to be useful in the management of Alzheimer’s disease. Curcumin readily crosses the blood-brain barrier and it can speed up the clearance of amyloid protein plaques.
In addition to these health benefits, studies also show that turmeric is useful for detoxifying the body. To do this, turmeric improves the expression of at least 2 important liver enzymes.
However, the effects of turmeric on the liver extends beyond mere detoxification. Turmeric increases the population of receptors for LDL (low-density lipoprotein or “bad”) cholesterol in the liver. This effect directly increases the breakdown of LDL cholesterol and the reduction of blood cholesterol levels.
In addition, the antioxidant effect of turmeric inhibits lipid peroxidation and prevents the oxidation of LDL cholesterol.
This is important for cardiovascular health because oxidized LDL cholesterol is responsible for the clogging and thickening of the arteries.
Lastly, turmeric can also improve cardiovascular health by its anti-platelet action. By preventing platelets from sticking together, turmeric prevents blood clot formation and can, therefore, reduce the risk of heart attack and stroke.
Most of the studies investigating the effects of turmeric or curcumin on cholesterol levels involve animal models. There are still very few studies done to determine whether the positive results seen in animal studies extend to humans.
A 1996 study published in the Indian Journal of Pharmacology detailed the hypolipidemic effects of turmeric extract in mice fed on high-cholesterol diet.
The researchers fed the mice on this diet for 60 days and observed that serum and liver cholesterol levels were significantly increased by the 15th day of the study. This increase continued as the mice continued on the high-cholesterol diet.
After giving these mice 5% turmeric extract, the researchers observed significant reduction in serum and liver cholesterol levels as well as triglyceride levels.
Giving the mice 10% turmeric extract lowered the cholesterol and triglyceride levels to normal values.
This study proves that turmeric can indeed lower blood cholesterol levels at least in mice. In addition, it also shows that the hypocholesterolemic effect of turmeric is dose-dependent.
A 2008 study published in the Journal of Bangladesh Pharmacological Society also demonstrated the cholesterol-lowering benefits of turmeric.
For the study, the researchers fed 20 male guinea pigs on free-range diet for 30 days before separating them into 4 groups. The first group received no supplementation while the other 3 groups were given turmeric, garlic and turmeric plus garlic.
The results of the study showed that both turmeric and garlic (whether used alone or in combination) lowered blood cholesterol levels.
This study not only demonstrated the hypocholesterolemic benefits of turmeric but also indicated that garlic can be safely added to turmeric to improve this lipid-lowering property.
In a 2005 study published in Medical Science Monitor: International Medical Journal of Experimental and Clinical Research, a group of researchers investigated the hypolipidemic and antioxidant benefits of curcumin in rats.
The researchers induced hypercholesterolemia in the rats by feeding them high-cholesterol diet for 7 days. Thereafter, they added 0.5% curcumin to the animals’ diet.
The study result showed that curcumin
The researchers confirmed that curcumin is the turmeric phytochemical responsible for reducing cholesterol levels. In addition, they determined that curcumin reduced lipid levels by interfering with the absorption, metabolism and excretion of cholesterol rather than by antioxidant mechanisms.
A much earlier study published in the Journal of Nutrition in 1970 reached similar conclusions.
In that study, the researchers demonstrated that curcumin lowered serum and liver cholesterol by 33% - 50% in a group of rats induced with hypercholesterolemia.
The researchers determined that the cholesterol-lowering effect of curcumin was caused by the increased fecal excretion of bile acids and cholesterol.
In another study done on rats, the researchers identified another mechanism by which curcumin reduces cholesterol levels. This study was published in the journal, Molecular and Cellular Biochemistry, in 1997.
After inducing diabetes in the rats with the drug, streptozotocin, the researchers divided them into 2 groups. The first group was placed on a high-cholesterol diet while the second group received a control diet. Both groups were given 0.5% curcumin.
The results showed that the levels of LDL cholesterol and VLDL (very low-density lipoprotein) cholesterol fell significantly with curcumin supplementation.
In addition, curcumin lowered triglyceride and phospholipid levels.
The cholesterol-lowering effect was higher among the rats fed on high-cholesterol diet than those fed on the control diet.
To determine how curcumin lowers blood cholesterol, the researchers measured the activities of 2 liver enzymes: HMG-CoA reductase and cholesterol-7-alpha-hydroxylase. They found that the activity of the second enzyme was raised in the livers of the rats fed curcumin.
Therefore, this study shows that one of the mechanisms by which curcumin lowers cholesterol levels is by increasing the breakdown of cholesterol in the liver.
A 2006 study published in the Journal of Nutritional Biochemistry investigated the effects of curcumin on human liver cell line.
This in vitro study was designed to closely investigate the mechanisms by which curcumin reduced cholesterol levels. The researchers demonstrated that the effect of curcumin on cholesterol metabolism extends deep to the genetic levels.
By treating the human liver cells with curcumin, the researchers showed that the turmeric phytochemical raised LDL-receptor mRNA seven-folds.
This finding shows that curcumin increases the uptake of cholesterol by the liver and its removal from the plasma. By increasing the population of LDL receptors in the liver, curcumin accelerates the breakdown of LDL cholesterol.
Besides the LDL receptors, the study also showed that curcumin increases the population of other receptors, such as liver X receptor and retinoic acid receptor, involved in lipid breakdown.
The researchers also affirmed that curcumin was not toxic to liver cells and that these cholesterol-lowering mechanisms were triggered at low doses easily attained by oral turmeric supplementation.
A 2008 study published in the African Journal of Food Science investigated the differences between the hypocholesterolemic effects of raw and cooked turmeric and red pepper.
The researchers induced hypercholesterolemia in a group of rats by feeding them a high-cholesterol diet for 8 weeks. During this period, the researchers gave different groups of the experimental rats dietary and heat-processed turmeric and red pepper.
This study is important because cooking heat has been shown to reduce the major phytochemicals in spices. Therefore, heat-processed turmeric contained a lower amount of curcumin than raw turmeric. There was also a significant loss of capsaicin from cooked red pepper.
The results of this study showed that both raw and cooked turmeric and red pepper significantly lowered cholesterol levels.
In fact, the differences between the hypocholesterolemic effects of raw and cooked forms of the spices were negligible.
The results showed that turmeric (and red pepper) reduced total serum cholesterol as well as LDL cholesterol levels.
In addition, the spices increased serum vitamin E concentration. The improved antioxidant protection significantly reduced lipid peroxidation in the liver.
A 1999 study published in the journal, Atherosclerosis, investigated the effect of turmeric extract on lipid oxidation and atherosclerosis in a small group of rabbits.
After feeding 18 rabbits with a cholesterol-rich diet for 7 weeks, the researchers divided them into 3 groups. One group received 1.66 mg/kg of turmeric extract while another group received double the dose. The rabbits in the third group were not given turmeric extract and they served as control.
The study results showed that only the low dose of turmeric extract reduced the peroxidation of LDL cholesterol even though both doses of herb actually reduced the level of total plasma cholesterol.
In addition, the lower dose of turmeric extract produced a bigger reduction in cholesterol, triglyceride and phospholipid levels than the high dose.
The researchers concluded that the appropriate dose of turmeric can reduce the risk of atherosclerosis and improve cardiovascular health. Therefore, turmeric supplementation should be considered for this purpose in humans.
A study similar to the above was published in the Journal of Atherosclerosis and Thrombosis in 2002.
In that study, the researchers obtained serum LDL samples from human volunteers and exposed them to 4 antioxidants (curcumin, tetrahydrocurcumin, probucol and alpha-tocopherol).
The results showed that probucol was the most effective of these antioxidants for inhibiting the oxidative modification of LDL cholesterol. Tetrahydrocurcumin was second to probucol and curcumin was the least effective antioxidant of the set.
Thereafter, the researchers tested tetrahydrocurcumin on a group of rabbits fed a high-cholesterol diet.
Compared to the results obtained from the control group, tetrahydrocurcumin reduced oxidative stress in the liver and kidneys and also reduced the severity of atherosclerotic lesions.
The researchers concluded that the curcuminoids in turmeric can reduce the risk of atherosclerosis by their antioxidant effects.
The results of this study also suggests that other turmeric curcuminoids besides curcumin can provide cardiovascular and cholesterol-lowering benefits.
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