WHAT IS THE SCIENTIFIC EVIDENCE? THE CLINICAL TRIAL EVIDENCE?
ARE THERE ANY CONTRADICATIONS?
WILL THE GOOD EFFECTS LAST?
FOR THE SKEPTIC
PUBLICATIONS
Over 180 scientific studies of the biological action of saffron have been published in the scientific literature; specifically, in the PubMed database maintained by the National Center for Biotechnology Information of the U.S. National Library of Medicine. This system of publication does not guarantee that every paper published is correct; only that it is subjected to the scrutiny of peer review, before publication.
This database is freely available at http://www.ncbi.nlm.nih.gov/pubmed/. It is an enormous database, but it can readily be searched for the words 'saffron' or 'crocus sativus'.
Several features of this literature are of interest:
• Scientific interest in the biological effects saffron has grown rapidly over the last 20 years. In the 1990's, ~ 20 studies were published in the scientific literature; in the 2000's over 120 papers were published, increasing from 4 in the year 2000 to over 25 in 2010. In the years 2011 to date, more than 100 additional papers have been published on saffron. Scientific interest continues to grow.
• Most were published from scientists in Iran (the world's #1 saffron producer – 47 papers counted); from Spain (another major produce – 21 papers), China, India, Greece, the USA (13 papers); only 4 from Australia.
• These papers have tested the value of saffron in preventing cancer, genotoxicity (damage to the DNA which encodes genes), depression, Alzheimer's disease, tissue repair following ischaemia, retinal degeneration, impotence, diabetic neuropathy, impotence and male infertility. The work has been done both in animal models of the diseases, and in humans, as clinical trials.
• Positive outcomes (i.e. saffron protects or helps repair tissues) have been reported for cancer (but not yet in clinical trial), genotoxicity, depression, dementia (Alzheimer's disease) and AMD (age-related macular degeneration). The male infertility trials were negative; and saffron as an aphrodisiac is reported to be 'not as good as Viagra'.
• The overall number of clinical trials is small (10, across several diseases). They are all Phase I (safety) or Phase II (small numbers, testing efficacy) trials. Multi-centre trials with large numbers of patients have not yet been reported.
• Taken over all, the outcome of this work is promising; but systematic testing will need to continue, to identify the full range of features of saffron needed before we can say we 'understand' it, especially dose-response relationships and the mechanisms of action.
So far, there is no evidence of which we are aware of any bad side effect of consuming saffron in the doses effective in the laboratory and in the clinic. This is not entirely surprising, given its long history of use in human food.
We particularly examined the literature on saffron and cancer. Saffron is protective to stressed tissue; in the present context it is protective to neurones in the retina of the eye.
What if saffron protects cancer cells? A survey of the studies on cancer show that, on the contrary, saffron slows the proliferation and spread of cancer cells, at least in animal models. It seems to do only good.
There is a principle of toxicology, however, that 'everything is toxic, in large enough doses'. Maybe because it is so expensive, and too insubstantial to form a meal, though a great spice, there is little evidence of saffron toxicity in the scientific literature. The "WHO Monographs on selected medicinal plants, Volume 3" (published by the WHO in Geneva in 2007) reviewed the properties of saffron, noting two scientific studies of saffron toxicity in rodents. These reported that the dose needed to kill rats or mice is measured in grams/kilogram, so 1,000 greater than required for the protective effect.
One intriguing possibility is that saffron relieves depression. There is only one clinical trial, which suggests that it is as effective as approved anti-depressants. But quite a few anecdotes – unpublished, uncontrolled observations – which suggest that one side effect of consuming saffron regularly is cheerfulness.
Which is presumably a good outcome for the individual; but might (in extremis) irritate one's carers.
Very few studies are available of how long the effects of saffron last. The clinical trial of saffron in AMD reported strong positive results, which lasted as long as saffron was used (3 months). Follow-up trials from this group, indicate that the improvements in retinal function induced by saffron last as long as the saffron is taken, at least up to 1 year, and fade slowly if saffron intake is stopped.
This is another area in which more trials and data are needed.
Skepticism is at the heart of science, but it is not the whole of the scientific method. Also essential to science are ideas; and essential to medical science is a commitment to deliver the treatments identified by biomedical research.
The study of saffron has reached a stage where – though the mechanism of its protective actions has not yet been fully defined and many questions remain to be answered about dose regimes and the duration of saffron's effects – it is appropriate to be offered as a novel treatment.
Continued investigation is essential; but withholding a possible treatment for people struggling with their vision now does not seem right, given the safety of saffron as a food supplement and the level of evidence available.
There are always more experiments to be done; always some unknown.
And always a human need.
Falsini B, Piccardi M, Minnella A, Savastano C, Capoluongo E, Fadda A, Balestrazzi E, Maccarone R, Bisti S (2011) Influence of saffron supplementation on retinal flicker sensitivity in early age-related macular degeneration. Invest Ophthalmol Vis Sci 51: 6118-6124
Natoli R, Zhu Y, Valter K, Bisti S, Eells J, Stone J (2010) Gene and noncoding RNA regulation underlying photoreceptor protection: microarray study of dietary antioxidant saffron and photobiomodulation in rat retina. Mol Vis 16: 1801-1822
Feizzadeh B, Afshari JT, Rakhshandeh H, Rahimi A, Brook A, Doosti H (2008) Cytotoxic effect of saffron stigma aqueous extract on human transitional cell carcinoma and mouse fibroblast. Urol J 5: 161-167
Hosseinzadeh H, Abootorabi A, Sadeghnia HR (2008) Protective effect of Crocus sativus stigma extract and crocin (trans-crocin 4) on methyl methanesulfonate-induced DNA damage in mice organs. DNA Cell Biol 27: 657-664
Goyal SN, Arora S, Sharma AK, Joshi S, Ray R, Bhatia J, Kumari S, Arya DS (2009) Preventive effect of crocin of Crocus sativus on hemodynamic, biochemical, histopathological and ultrastuctural alterations in isoproterenol-induced cardiotoxicity in rats. Phytomedicine 17: 227-232
Dhar A, Mehta S, Dhar G, Dhar K, Banerjee S, Van Veldhuizen P, Campbell DR, Banerjee SK (2009) Crocetin inhibits pancreatic cancer cell proliferation and tumor progression in a xenograft mouse model. Mol Cancer Ther 8: 315-323
Ordoudi SA, Befani CD, Nenadis N, Koliakos GG, Tsimidou MZ (2009) Further examination of antiradical properties of Crocus sativus stigmas extract rich in crocins. J Agric Food Chem 57: 3080-3086
Maccarone R, Di Marco S, Bisti S (2008) Saffron supplement maintains morphology and function after exposure to damaging light in mammalian retina. Invest Ophthalmol Vis Sci 49: 1254-1261
Chryssanthi DG, Dedes PG, Karamanos NK, Cordopatis P, Lamari FN (2010) Crocetin Inhibits Invasiveness of MDA-MB-231 Breast Cancer Cells via Downregulation of Matrix Metalloproteinases. Planta Med 77:146-51
Bathaie SZ, Bolhasani A, Hoshyar R, Ranjbar B, Sabouni F, Moosavi-Movahedi AA (2007) Interaction of saffron carotenoids as anticancer compounds with ctDNA, Oligo (dG.dC)15, and Oligo (dA.dT)15. DNA Cell Biol 26: 533-540
Schmidt M, Betti G, Hensel A (2007) Saffron in phytotherapy: pharmacology and clinical uses. Wien Med Wochenschr 157: 315-319
Saleem S, Ahmad M, Ahmad AS, Yousuf S, Ansari MA, Khan MB, Ishrat T, Islam F (2006) Effect of Saffron (Crocus sativus) on neurobehavioral and neurochemical changes in cerebral ischemia in rats. J Med Food 9: 246-253
Giaccio M (2004) Crocetin from saffron: an active component of an ancient spice. Crit Rev Food Sci Nutr 44: 155-172
Ochiai T, Ohno S, Soeda S, Tanaka H, Shoyama Y, Shimeno H (2004) Crocin prevents the death of rat pheochromyctoma (PC-12) cells by its antioxidant effects stronger than those of alpha-tocopherol. Neurosci Lett 362: 61-64
Akhondzadeh S, Fallah-Pour H, Afkham K, Jamshidi AH, Khalighi-Cigaroudi F (2004) Comparison of Crocus sativus L. and imipramine in the treatment of mild to moderate depression: a pilot double-blind randomized trial [ISRCTN45683816]. BMC Complement Altern Med 4: 12
Abdullaev F (2003) Crocus sativus against cancer. Arch Med Res 34: 354
Abdullaev FI (1994) Inhibitory effect of crocetin on intracellular nucleic acid and protein synthesis in malignant cells. Toxicol Lett 70: 243-251
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