11 Outstanding Turmeric Tea Benefits and How to Make It

This recipe will help you reap the full benefits of turmeric tea during the cold, flu, and especially coronavirus season.

Although the list of ingredients may seem strange at first glance, it tastes surprisingly good. And I am not a big tea drinker. However, I took a comprehensive look at the health benefits of turmeric and ginger based on science. So you can better understand what turmeric tea is good for.

Turmeric Tea | Health | Benefits | Recipe | Best Time | Side Effects

What Is Turmeric Tea?

Turmeric tea is made by brewing freshly grounded turmeric root or turmeric powder. In contrast, most other teas are made from dried leaves.

Turmeric originates from Southeast Asia and belongs to the ginger family. Chinese and the Ayurvedic medicine of India have been using it as an herbal remedy for thousands of years.

Furthermore, they even use this great spice to treat various ailments in these regions.

Curcumin is the essential active compound in turmeric root. Also, it gives turmeric tea its bright yellow color and health benefits.

These benefits of turmeric tea include the relief of:

• Acne
• Arthritis
• Colds
• Depressions
• Inflammations
• Joint Pain
• Upset stomachs

But ginger in turmeric tea also has its benefits, as we will see in more detail.

Is Turmeric Tea Good for You?

As long as you don’t buy a ready-made mixture, there is no reason why turmeric tea shouldn’t be healthy.

In short, the risk of side effects is more significant with eating curry than homemade turmeric tea.

Accordingly, it’s no coincidence that Ayurvedic medicine has been using turmeric tea for thousands of years. Due to its primary ingredients, turmeric, and ginger, the tea has anti-inflammatory, antibacterial, and antioxidative properties.

What Are the Benefits of Turmeric Tea?

Enough talk! Here are the significant health benefits of turmeric tea, according to the heaps of scientific evidence:

1. Antioxidative

Due to curcuminoids, turmeric, the essential tea ingredient, offers antioxidative properties.

Because of these antioxidant properties, Ayurvedic medicine has used turmeric for centuries (Nagpal et al. 2013¹).

Furthermore, curcumin gives tea and curry seasonings their characteristic yellow color.

Just how effective turmeric can become apparent when you consider the ORAC value of over 127000.

ORAC (Oxygen Radical Absorbance Capacity) stands for the property of rendering free oxygen radicals harmless.

Free radicals are additional oxygen molecules that can cause tissue damage when they contact.

Curcuminoids intercept free radicals over five times more than vitamins C and E, and they can also absorb the free hydroxyl radical, considered the most reactive one (Menon et al. 2007²).

Thus, curcumin can fight diseases ranging from bronchitis to insulin resistance and even slow aging.

On top of that, ginger adds further antioxidant benefits to turmeric tea (Shan et al. 2005³).

2. Anti-Inflammatory

The primary ingredients, turmeric and ginger, give turmeric tea its anti-inflammatory properties.

Accordingly, studies suggest curcumin has anti-inflammatory medical quality properties without undesirable side effects (Lao et al. 2006⁴).

With this in mind, chronic inflammation is a significant driver of modern diseases like type-2 diabetes, cancer, or rheumatoid arthritis.

Although curcumin is one of the most potent natural anti-inflammatory compounds, it is hard for the human body to absorb it properly.

Therefore, any dish, drink, or dietary supplement with turmeric should also contain black pepper.

Because black pepper contains piperine, the human body can absorb curcumin 20 times more efficiently (Shoba et al. 1998⁵).

Against this background, human studies now confirm the anti-inflammatory benefits of curcumin in the human body (Chainani-Wu 2003⁶).

Besides turmeric, a ginger family plant, ginger offers medical-grade anti-inflammatory properties.

Accordingly, ginger can outshine some drugs’ effects and significantly reduce side effects (Grzanna et al. 2015⁷).

3. Immune Boosting

With such an accumulation of anti-inflammatory and antioxidant ingredients, it is no wonder that ginger turmeric tea can strengthen the immune system.

According to studies, the essential active compound curcumin modulates the immune system in a way that counteracts the following diseases (Jagetia et al. 2007⁸):

• Allergies
• Alzheimer
• Arthritis
• Asthma
• Atherosclerosis
• Cancer
• Heart Diseases
• Type-2-Diabetes

4. Antiviral and Antibacterial

Against the current coronavirus pandemic background, the benefits of turmeric tea can come in handy. Accordingly, Ayurvedic medicine has used ginger turmeric tea to remedy the flu and colds.

Since curcumin offers antibacterial and antiviral effects, it can help with infections (Moghadamtousi et al. 2014⁹).

Additionally, fresh ginger in turmeric tea fights respiratory infections and bacteria growth (Gull et al. 2012¹⁰; Chang et al. 2013¹¹).

5. Digestion-Improving

Furthermore, ginger can help relieve digestive ailments by accelerating gastric emptying (Hu et al. 2011¹²).

Chronic indigestion, or dyspepsia, is characterized by discomfort in the stomach’s upper part, often caused by delayed gastric emptying.

Besides, turmeric can improve fat digestion by increasing the liver’s bile production by up to 62% (Dulbecco et al. 2013¹³).

Thus, these properties are particularly useful for people who are just starting a ketogenic diet and have difficulty digesting fat.

Ultimately, turmeric can help people suffering from an inflammatory digestive disorder called ulcerative colitis (Hanai et al. 2006¹⁴).

6. Blood Sugar Regulating

Daily adding fresh ginger to tea can lower blood sugar levels by over 10%.

Accordingly, ginger could reduce hemoglobin A1C, a long-term blood glucose marker, by 10% in this recent study (Khandouzi et al. 2015¹⁵).

If you drink ginger turmeric tea because of its blood sugar-regulating effect, you should not sweeten it.

Although many recipes include honey, it will ruin any positive effect on weight loss.

7. Hearth Healthy

Our western world is plagued by nothing more than heart diseases. Accordingly, many of the causes of death are attributable to cardiovascular issues.

Against this background, treating yourself to a cup of turmeric tea every day makes perfect sense.

Since curcumin has potent anti-inflammatory and antioxidant effects, it can influence heart health as follows (Akazawa et al. 2012¹⁶; Shah et al. 1999¹⁷; Prakash et al. 2011¹⁸):

• Improves vascular functions
• Lowers blood pressure
• Prevents heart attacks and strokes

8. Cancer-Fighting

According to many studies, curcumin helps prevent cancer and inhibit tumor growth (Takada et al. 2004¹⁹).

Moreover, some researchers say curcumin can kill cancer cells (Ravindran et al. 2009²⁰).

Besides turmeric, research attributes cancer-inhibiting effects to ginger (Poltronieri et al. 2014²¹).

Nevertheless, home remedies such as ginger-turmeric tea cannot replace professional, individual treatments.

9. Cognition-Enhancing

Curcumin can increase the release of the neuronal growth hormone BDNF, which can form new nerve cells in the brain (Xu et al. 2006²²).

Therefore, researchers also say that turmeric helps to prevent the following neurodegenerative diseases (Monroy et al. 2014²³):

• Alzheimer
• Huntington
• Parkinson

In particular, it can prevent this disease through curcumin’s ability to prevent or eliminate plaque accumulation.

Therefore, research also suggests that curcumin could reverse age-related limitations in brain function.

Moreover, further studies suggest that ginger in turmeric tea can also improve memory function and counteract Alzheimer’s disease (Saenghong et al. 2011²⁴; Zeng et al. 2013²⁵).

10. Antidepressive

The positive effect of curcumin on brain function can relieve stress and depression in addition to neurodegenerative diseases (Mishra et al. 2008²⁶).

For example, scientists suggest that the benefits of turmeric reduce anxiety and improve mental health (Hurley et al. 2013²⁷).

Partially, these properties are due to the increased BDNF release (Kulkarni et al. 2008²⁸).

Furthermore, a randomized controlled trial in people with major depressive disorder suggests that turmeric may be a safe and effective treatment for such conditions (Sanmukhani et al. 2014²⁹).

11. Pain-Relieving

Curcumin not only reduces pain and swelling of joints affected by rheumatoid arthritis but also (Chandran et al. 2012³⁰):

• Bone and muscle ailments
• Headaches and migraines
• Menstrual Pain

Moreover, ginger in turmeric tea is also known for its effect against postoperative pain and menstrual cramps (Rayati et al. 2017³¹).

A study suggests ginger is as effective as the widely used ibuprofen (Daily et al. 2015³²).

How to Make Turmeric Tea

The basis for this simple turmeric tea recipe is finely chopped ginger, turmeric powder, and lemon juice. Although many people add honey, I don’t think it is necessary.

This turmeric tea recipe guarantees a fresh, earthy, sweet, satisfying flavor.

Furthermore, honey and sweeteners reduce the positive effects on blood sugar, inflammation, and weight loss.

However, I like a spicy pinch of chili during the cold season.

Unlike chili, black pepper is obligatory because it boosts the bioavailability of curcumin, allowing the body to absorb it much more effectively (Shoba et al. 1998³³).

Although many recipes prefer fresh turmeric root, I must say that tea with turmeric powder tastes better.

The same applies to the popular turmeric tea latte. This golden milk represents the dessert variant of turmeric tea, enriched with coconut milk and cinnamon.

Steep Time

This simple ginger turmeric tea recipe needs to steep for about 10 minutes. This way, the ingredients can blend.

If you use fresh turmeric instead of the powder in the recipe to make turmeric tea, allow it to steep for up to 15 minutes.

How Often Should You Drink Turmeric Tea?

How much turmeric tea you can drink daily depends on your daily routine.

Unless you are fasting intermittently, turmeric tea can be a warming agent in the morning.

Although turmeric tea has hardly any calories, the variety of ingredients can already be enough to break the fast.

If it is sweetened, turmeric tea not only breaks a fast but also loses some of its benefits on weight loss, blood sugar, and inflammation.

You can hardly drink too much turmeric tea unless you already take a dietary supplement with curcumin.

The Best Time to Drink Turmeric Tea

Homemade turmeric tea can be drunk in between as any other tea. In short: Teatime? Any time!

Hence, there is no single best time to drink turmeric tea. However, it can be smart to drink turmeric tea before or with lunch and dinner since it aids digestion.

Also, some people like it after a meal. However, I would not drink it at night before bedtime since your digestive tract needs some rest too.

Are There Any Side Effects?

Turmeric is generally considered safe both as a spice and as a tea. Therefore, most people can consume it without serious side effects.

As said before, curry stew is most likely more dangerous than homemade ginger turmeric tea since you already know the ingredients.

Consequently, studies on turmeric and ginger have reported few or no side effects. In this context, these spices perform better than widely used drugs (Lao et al. 2006³⁴; Grzanna et al. 2015³⁵).

However, some people may experience the following isolated side effects:

• Diarrhea
• Nausea
• Upset stomach

However, these side effects are usually caused by excessive consumption of turmeric.

Without additional turmeric supplements, such high doses are difficult to achieve. Therefore, turmeric tea is a healthy alternative to dietary supplements, which pregnant women should avoid.

For example, high doses due to the oxalates in turmeric can promote gall or kidney stones. Moreover, there is the possibility that people are allergic to turmeric, although this tends to be rare.

The Takeaway

Now you know how to make turmeric tea, its health benefits, and last but not least, the exact ingredients: Natural spices, water, and a dash of lemon.

In contrast, you cannot say that with dietary supplements.

But most people blindly trust any pill and hesitate to take 5 minutes of spare time for their health.

However, turmeric tea benefits can improve various ailments – from minor aches to Alzheimer’s and cancer prevention.

Nevertheless, turmeric tea is not a panacea that can replace professional treatments. But if you drink unsweetened, it will flatter your glucose metabolism and skin.

The same is true for a turmeric tea latte. If you haven’t tried the soothing and creamy recipe with coconut oil or ghee, you should make your first golden milk now.

Frequently Asked Questions (FAQ)

How often should you drink turmeric tea?

How often you drink turmeric tea is totally up to you. Unless you are allergic or already take curcumin supplements, you can even drink it daily.

What are 5 medicinal benefits of turmeric?

Turmeric is anti-inflammatory, antioxidative, blood sugar-regulating, cancer-fighting, and immune-boosting.

Is it OK to drink turmeric tea everyday?

Unless they are allergic or take high doses of supplements, most people can drink turmeric tea daily.

Studies

#1-7

¹Nagpal M, Sood S. Role of curcumin in systemic and oral health: An overview. J Nat Sci Biol Med. 2013 Jan;4(1):3-7. doi: 10.4103/0976-9668.107253. PubMed PMID: 23633828; PubMed Central PMCID: PMC3633300.

²Menon VP, Sudheer AR. Antioxidant and anti-inflammatory properties of curcumin. Adv Exp Med Biol. 2007;595:105-25. doi: 10.1007/978-0-387-46401-5_3. Review. PubMed PMID: 17569207.

³Shan B, Cai YZ, Sun M, Corke H. Antioxidant capacity of 26 spice extracts and characterization of their phenolic constituents. J Agric Food Chem. 2005 Oct 5;53(20):7749-59. doi: 10.1021/jf051513y. PubMed PMID: 16190627.

⁴Lao CD, Ruffin MT 4th, Normolle D, Heath DD, Murray SI, Bailey JM, Boggs ME, Crowell J, Rock CL, Brenner DE. Dose escalation of a curcuminoid formulation. BMC Complement Altern Med. 2006 Mar 17;6:10. doi: 10.1186/1472-6882-6-10. PubMed PMID: 16545122; PubMed Central PMCID: PMC1434783.

⁵Shoba G, Joy D, Joseph T, Majeed M, Rajendran R, Srinivas PS. Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers. Planta Med. 1998 May;64(4):353-6. doi: 10.1055/s-2006-957450. PubMed PMID: 9619120.

⁶Chainani-Wu N. Safety and anti-inflammatory activity of curcumin: a component of tumeric (Curcuma longa). J Altern Complement Med. 2003 Feb;9(1):161-8. doi: 10.1089/107555303321223035. Review. PubMed PMID: 12676044.

⁷Grzanna R, Lindmark L, Frondoza CG. Ginger–an herbal medicinal product with broad anti-inflammatory actions. J Med Food. 2005 Summer;8(2):125-32. doi: 10.1089/jmf.2005.8.125. Review. PubMed PMID: 16117603.

#8-13

⁸Jagetia GC, Aggarwal BB. “Spicing up” of the immune system by curcumin. J Clin Immunol. 2007 Jan;27(1):19-35. doi: 10.1007/s10875-006-9066-7. Epub 2007 Jan 9. PMID: 17211725.

⁹Moghadamtousi SZ, Kadir HA, Hassandarvish P, Tajik H, Abubakar S, Zandi K. A review on antibacterial, antiviral, and antifungal activity of curcumin. Biomed Res Int. 2014;2014:186864. doi: 10.1155/2014/186864. Epub 2014 Apr 29. Review. PubMed PMID: 24877064; PubMed Central PMCID: PMC4022204.

¹⁰Gull I, Saeed M, Shaukat H, Aslam SM, Samra ZQ, Athar AM. Inhibitory effect of Allium sativum and Zingiber officinale extracts on clinically important drug resistant pathogenic bacteria. Ann Clin Microbiol Antimicrob. 2012 Apr 27;11:8. doi: 10.1186/1476-0711-11-8. PubMed PMID: 22540232; PubMed Central PMCID: PMC3418209.

¹¹Chang JS, Wang KC, Yeh CF, Shieh DE, Chiang LC. Fresh ginger (Zingiber officinale) has anti-viral activity against human respiratory syncytial virus in human respiratory tract cell lines. J Ethnopharmacol. 2013 Jan 9;145(1):146-51. doi: 10.1016/j.jep.2012.10.043. Epub 2012 Nov 1. PubMed PMID: 23123794.

¹²Hu ML, Rayner CK, Wu KL, Chuah SK, Tai WC, Chou YP, Chiu YC, Chiu KW, Hu TH. Effect of ginger on gastric motility and symptoms of functional dyspepsia. World J Gastroenterol. 2011 Jan 7;17(1):105-10. doi: 10.3748/wjg.v17.i1.105. PMID: 21218090; PMCID: PMC3016669.

¹³Dulbecco P, Savarino V. Therapeutic potential of curcumin in digestive diseases. World J Gastroenterol. 2013 Dec 28;19(48):9256-70. doi: 10.3748/wjg.v19.i48.9256. PMID: 24409053; PMCID: PMC3882399.

#14-19

¹⁴Hanai H, Iida T, Takeuchi K, Watanabe F, Maruyama Y, Andoh A, Tsujikawa T, Fujiyama Y, Mitsuyama K, Sata M, Yamada M, Iwaoka Y, Kanke K, Hiraishi H, Hirayama K, Arai H, Yoshii S, Uchijima M, Nagata T, Koide Y. Curcumin maintenance therapy for ulcerative colitis: randomized, multicenter, double-blind, placebo-controlled trial. Clin Gastroenterol Hepatol. 2006 Dec;4(12):1502-6. doi: 10.1016/j.cgh.2006.08.008. Epub 2006 Nov 13. PMID: 17101300.

¹⁵Khandouzi N, Shidfar F, Rajab A, Rahideh T, Hosseini P, Mir Taheri M. The effects of ginger on fasting blood sugar, hemoglobin a1c, apolipoprotein B, apolipoprotein a-I and malondialdehyde in type 2 diabetic patients. Iran J Pharm Res. 2015 Winter;14(1):131-40. PubMed PMID: 25561919; PubMed Central PMCID: PMC4277626.

¹⁶Akazawa N, Choi Y, Miyaki A, Tanabe Y, Sugawara J, Ajisaka R, Maeda S. Curcumin ingestion and exercise training improve vascular endothelial function in postmenopausal women. Nutr Res. 2012 Oct;32(10):795-9. doi: 10.1016/j.nutres.2012.09.002. Epub 2012 Oct 15. PubMed PMID: 23146777.

¹⁷Shah BH, Nawaz Z, Pertani SA, Roomi A, Mahmood H, Saeed SA, Gilani AH. Inhibitory effect of curcumin, a food spice from turmeric, on platelet-activating factor- and arachidonic acid-mediated platelet aggregation through inhibition of thromboxane formation and Ca2+ signaling. Biochem Pharmacol. 1999 Oct 1;58(7):1167-72. doi: 10.1016/s0006-2952(99)00206-3. PubMed PMID: 10484074.

¹⁸Prakash P, Misra A, Surin WR, Jain M, Bhatta RS, Pal R, Raj K, Barthwal MK, Dikshit M. Anti-platelet effects of Curcuma oil in experimental models of myocardial ischemia-reperfusion and thrombosis. Thromb Res. 2011 Feb;127(2):111-8. doi: 10.1016/j.thromres.2010.11.007. Epub 2010 Dec 8. PubMed PMID: 21144557.

¹⁹Takada Y, Bhardwaj A, Potdar P, Aggarwal BB. Nonsteroidal anti-inflammatory agents differ in their ability to suppress NF-kappaB activation, inhibition of expression of cyclooxygenase-2 and cyclin D1, and abrogation of tumor cell proliferation. Oncogene. 2004 Dec 9;23(57):9247-58. doi: 10.1038/sj.onc.1208169. PubMed PMID: 15489888.

#20-26

²⁰Ravindran J, Prasad S, Aggarwal BB. Curcumin and cancer cells: how many ways can curry kill tumor cells selectively?. AAPS J. 2009 Sep;11(3):495-510. doi: 10.1208/s12248-009-9128-x. Epub 2009 Jul 10. Review. PubMed PMID: 19590964; PubMed Central PMCID: PMC2758121.

²¹Poltronieri J, Becceneri AB, Fuzer AM, Filho JC, Martin AC, Vieira PC, Pouliot N, Cominetti MR. [6]-gingerol as a cancer chemopreventive agent: a review of its activity on different steps of the metastatic process. Mini Rev Med Chem. 2014 Apr;14(4):313-21. doi: 10.2174/1389557514666140219095510. Review. PubMed PMID: 24552266.

²²Xu Y, Ku B, Tie L, Yao H, Jiang W, Ma X, Li X. Curcumin reverses the effects of chronic stress on behavior, the HPA axis, BDNF expression and phosphorylation of CREB. Brain Res. 2006 Nov 29;1122(1):56-64. doi: 10.1016/j.brainres.2006.09.009. Epub 2006 Oct 3. PubMed PMID: 17022948.

²³Monroy A, Lithgow GJ, Alavez S. Curcumin and neurodegenerative diseases. Biofactors. 2013 Jan-Feb;39(1):122-32. doi: 10.1002/biof.1063. Epub 2013 Jan 10. Review. PubMed PMID: 23303664; PubMed Central PMCID: PMC3578106.

²⁴Saenghong N, Wattanathorn J, Muchimapura S, Tongun T, Piyavhatkul N, Banchonglikitkul C, Kajsongkram T. Zingiber officinale Improves Cognitive Function of the Middle-Aged Healthy Women. Evid Based Complement Alternat Med. 2012;2012:383062. doi: 10.1155/2012/383062. Epub 2011 Dec 22. PubMed PMID: 22235230; PubMed Central PMCID: PMC3253463.

²⁵Zeng GF, Zhang ZY, Lu L, Xiao DQ, Zong SH, He JM. Protective effects of ginger root extract on Alzheimer disease-induced behavioral dysfunction in rats. Rejuvenation Res. 2013 Apr;16(2):124-33. doi: 10.1089/rej.2012.1389. PubMed PMID: 23374025.

²⁶Mishra S, Palanivelu K. The effect of curcumin (turmeric) on Alzheimer’s disease: An overview. Ann Indian Acad Neurol. 2008 Jan;11(1):13-9. doi: 10.4103/0972-2327.40220. PubMed PMID: 19966973; PubMed Central PMCID: PMC2781139.

#27-33

²⁷Hurley LL, Akinfiresoye L, Nwulia E, Kamiya A, Kulkarni AA, Tizabi Y. Antidepressant-like effects of curcumin in WKY rat model of depression is associated with an increase in hippocampal BDNF. Behav Brain Res. 2013 Feb 15;239:27-30. doi: 10.1016/j.bbr.2012.10.049. Epub 2012 Nov 8. PubMed PMID: 23142609; PubMed Central PMCID: PMC3525727.

²⁸Kulkarni SK, Bhutani MK, Bishnoi M. Antidepressant activity of curcumin: involvement of serotonin and dopamine system. Psychopharmacology (Berl). 2008 Dec;201(3):435-42. doi: 10.1007/s00213-008-1300-y. Epub 2008 Sep 3. PubMed PMID: 18766332.

²⁹Sanmukhani J, Satodia V, Trivedi J, Patel T, Tiwari D, Panchal B, Goel A, Tripathi CB. Efficacy and safety of curcumin in major depressive disorder: a randomized controlled trial. Phytother Res. 2014 Apr;28(4):579-85. doi: 10.1002/ptr.5025. Epub 2013 Jul 6. PMID: 23832433.

³⁰Chandran B, Goel A. A randomized, pilot study to assess the efficacy and safety of curcumin in patients with active rheumatoid arthritis. Phytother Res. 2012 Nov;26(11):1719-25. doi: 10.1002/ptr.4639. Epub 2012 Mar 9. PubMed PMID: 22407780.

³¹Rayati F, Hajmanouchehri F, Najafi E. Comparison of anti-inflammatory and analgesic effects of Ginger powder and Ibuprofen in postsurgical pain model: A randomized, double-blind, case-control clinical trial. Dent Res J (Isfahan). 2017 Jan-Feb;14(1):1-7. doi: 10.4103/1735-3327.201135. PubMed PMID: 28348610; PubMed Central PMCID: PMC5356382.

³²Daily JW, Zhang X, Kim DS, Park S. Efficacy of Ginger for Alleviating the Symptoms of Primary Dysmenorrhea: A Systematic Review and Meta-analysis of Randomized Clinical Trials. Pain Med. 2015 Dec;16(12):2243-55. doi: 10.1111/pme.12853. Epub 2015 Jul 14. Review. PubMed PMID: 26177393.

³³Shoba G, Joy D, Joseph T, Majeed M, Rajendran R, Srinivas PS. Influence of piperine on the pharmacokinetics of curcumin in animals and human volunteers. Planta Med. 1998 May;64(4):353-6. doi: 10.1055/s-2006-957450. PubMed PMID: 9619120.

#34-35

³⁴Lao CD, Ruffin MT 4th, Normolle D, Heath DD, Murray SI, Bailey JM, Boggs ME, Crowell J, Rock CL, Brenner DE. Dose escalation of a curcuminoid formulation. BMC Complement Altern Med. 2006 Mar 17;6:10. doi: 10.1186/1472-6882-6-10. PubMed PMID: 16545122; PubMed Central PMCID: PMC1434783.

³⁵Grzanna R, Lindmark L, Frondoza CG. Ginger–an herbal medicinal product with broad anti-inflammatory actions. J Med Food. 2005 Summer;8(2):125-32. doi: 10.1089/jmf.2005.8.125. Review. PubMed PMID: 16117603.