Asparagus root lowers cholesterol, nurtures heart

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September 3, 2007  
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CM NEWS – Asparagus roots, or tian dong (?? or ???) can lower cholesterol and blood lipid, thus help prevent atherosclerosis and other cardiovascular diseases, a new study says.

asparagus-root.jpgHyperlipidemia and hypercholesteremia are major risk factors for atherosclerosis and cardiovascular diseases. Atherosclerotic cardiovascular disease is rapidly becoming a major cause of death in many societies throughout the world due to changed dietary habits and occupational stress. In recent years, natural compounds found in plants are gaining scientific attention for their potential therapeutic value in fighting multifactorial atherosclerotic disorders.

A study done at the Department of Biosciences, Sardar Patel University in India investigated the hypocholesteremic and antioxidant potential of the asparagus root root in both normal and hypercholesteremic animals. The results are published in medical journal Evidence-based Complementary and Alternative Medicine.

What is atherosclerosis? The hallmark of atherosclerosis is the accumulation of cells containing excessive lipids (i.e. foam cells) within the arterial wall. The major risk factors for the development of atherosclerosis are hypercholesteremia and elevated low-density lipoprotein cholesterol (LDL-C) concentration. Persistent hypercholesteremia results from prolonged circulation of lipid-rich lipoproteins that increase oxidative stress leading to oxidative modification of LDL to oxy-LDL.

In the present study, normal and hypercholesteremic male albino rats were administered with root powder of asparagus (5 and 10 g% dose levels) along with normal and hypercholesteremic diets, respectively, for a duration of 4 weeks.

Plasma and hepatic lipid profiles, fecal sterol, bile acid excretion and hepatic antioxidant activity were assessed.

What is asparagus root? A perennial with a woody root stock, asparagus grows from 1 to 5 feet high. The female Asparagus plant is slimmer than the male, which is shorter and stockier.

The dried root of asparagus is used in Chinese and Indian medicines as a tonic, galactogogue, aphrodisiac, rejuvenator, antispasmodic, antiulcerous and antiinflammatory. The medicinal/pharmacological value of asparagus root is attributed to the presence of steroidal saponins and sapogenins. The root of asaparagus is also used in the treatment of nervous disorders, dyspepsia, diarrhea, dysentery, tumours, hyperdipsia, neuropathy and hepatopathy. This plant is reported to have immunostimulant, antihepatotoxic and antioxytocic activities. Recent reports on asparagus indicate that the root extracts have antioxidant and antidiarrheal activities in laboratory animals.

Asparagus has also been used in its wild form in Ancient Greece and Rome as a natural diuretic that flushes out the kidneys and helps prevent the formation of kidney stones. It is because that the asparagus acts to increase cellular activity in the kidneys and thus increases the rate of urine production.

Asparagus roots also encourages evacuation of the bowels by increasing fecal bulk with undigested fiber. The roots are considered diuretic and laxative and are said to induce sweating, an they are recommended for gout, dropsy and rheumatism.

Chinese medicine says the asparagus root can increase feelings of compassion and love. In India, Asparagus is used to promote fertility, reduce menstrual cramping and increase milk production in nursing mothers.

In the Eastern and Western world, it has been touted as an aphrodisiac. These customs and beliefs are not mere superstition – the root contains compounds called steroidal glycosides (asparagoside) that directly affect hormone production and may very well influence emotions.

Chinese studies report that the roots may also lower blood pressure. The powdered seeds have antibiotic properties and help to relieve nausea while calming the stomach. Japanese studies report that green Asparagus aids protein conversion into amino acids.

Asparagus is also high in folic acid, which is essential for production of new red blood cells. Other primary chemical constituents of Asparagus include essential oil, asparagine, arginine, tyrosine, flavonoids (kaempferol, quercitin, rutin), resin and tannin.

The researchers found that rats that took diet with asparagus root powder have a reduction in their plasma and hepatic lipid profiles. Other observations include: increased fecal excretion of cholesterol, neutral sterol and bile acid, and increases in hepatic HMG-CoA reductase activity and bile acid content in hypercholesteremic rats.

Further, the asparagus root diet also improved the hepatic antioxidant status (catalase, SOD and ascorbic acid levels). However, there were no significant changes in lipid and antioxidant profiles occurred in rats with normal cholesterol levels.

The researchers explain that the lipid-lowering effects of the asparagus root in hypercholesteremic rats are related primarily to an increased excretion of cholesterol, neutral sterols, bile acid and an increase in hepatic bile acid content. In this context, the phytosterol and saponin contents of asparagus root could be responsible.

On one hand phytosterols are reported to compete and displace cholesterol from the intestinal bile acid micelles and decrease the cholesterol circulation, the researchers say. On the other hand, saponins precipitate cholesterol from micelles and interfere with enterohepatic circulation of bile acids making it unavailable for intestinal absorption of cholesterol leading to a reduction in plasma cholesterol levels.

Although the main component of the Asparagus root is a steroidal saponin, the root also contains alkaloids, flavonoids, sterols, terpenes, tannins, phenolics and mucilage.

In all, the results of the present study indicate that the potent therapeutic phyto-components present in the asparagus root i.e. phytosterols, saponins, polyphenols, flavonoids and ascorbic acid, could be responsible for increased bile acid production, elimination of excess cholesterol and elevation of hepatic antioxidant status in hypercholesteremic conditions.

[eCAM, doi:10.1093/ecam/nem091]