Numerous cancer survey studies have linked various dietary components with a protective effect. One of particular interest is lycopene, the bright red carotenoid in tomatoes, watermelon and pink grapefruit. Several studies link increased consumption of tomatoes and tomato products with a reduced risk, even as little as two to four servings of tomato sauce weekly.1
However, as with any topic in medicine, dissenting opinions exist. A recent study performed on more than 21,000 men showed no protective effect of higher blood lycopene levels against subsequent prostate cancer.2 Because individual variability for lycopene absorption is a significant concern,1 measurement of food intake may not accurately reflect what actually enters the bloodstream.
Thus, studies with lycopene supplements may be the only way in which one can discern a true, lycopene-specific effect. In one study, researchers gave 26 men with localised prostate cancer a proprietary tomato extract (Lyc-O-Mato) twice daily for three to four weeks, providing 15mg lycopene and numerous other bioactives.3 The control group received no supplement or placebo. This preceded surgical removal of the prostate (radical prostatectomy). The researchers found that the supplement may have a favourable effect on the outcome of prostate cancer, but this study did not measure prostate tumour markers before supplementation, thus it is unclear if the supplement indeed had a therapeutic effect.
More interestingly, the average blood lycopene concentration did not increase in the supplemented group, reinforcing the point that absorption may be more important than dose.
In contrast, a study where men were given daily servings of pasta prepared with tomato sauce containing 30mg lycopene experienced significant increases in both blood and prostate lycopene concentrations after three weeks.4 Tomatoes and their food products appear to offer the best source for minimising prostate cancer risk.1
HA Hydrates Skin
Hyaluronic acid (HA, or hyaluronan), a noted constituent in skin cells, is a polymer of a D-glucuronic acid and N-acetyl-glucosamine. HA can be considered a 'scaffold' upon which connective tissues attach. Because HA and similar molecules in the skin can bind up to 1,000 times their weight in water, they effectively 'hydrate' and 'tone' skin.5
Because HA in the skin decreases with age, numerous cosmetic companies are adding HA to products. The natural source of concentrated HA comes from the combs of roosters (cockscomb) or animal collagen extracts, while the bioengineered source (which is more expensive to produce) employs bacterial fermentation.
HA injections have been used widely in other countries for soft-tissue augmentation (lips, eyelids, wrinkle reduction).6 A recent study showed a 2.5 per cent HA gel (much higher than that added to cosmetics) reduced some of the signs of solar 'spots' (keratoses), but that its effects did not last two to three weeks after participants discontinued use of the product.7
As a supplement, there do not appear to be any published controlled studies showing HA or HA-containing oral products to have a measurable, objective impact upon skin. When ingested, bacteria in the intestines or immune cells in intestinal cells divide HA into smaller fragments.8,9 However, these HA fragments may exert antioxidant activity wherever they land.10 What is most challenging is the journey HA, as a big polymer or its fragments, would need to make to hone in on skin cells and exert anti-aging effects from afar. For now, high-concentration alpha-hydroxy acid (glycolic acid) appears to be an effective way of boosting skin HA and appearance.11
Anthony Almada, BSc, MSc, is the president and chief scientific officer of IMAGINutrition Inc and has been a co-investigator on more than 60 randomised controlled trials.
1. Giovannucci E. A review of epidemiologic studies of tomatoes, lycopene, and prostate cancer. Exp Biol Med 2002;227:852-59.
2. Huang HY, et al. Prospective study of antioxidant micronutrients in the blood and the risk of developing prostate cancer. Am J Epidemiol 2003157:335-44.
3. Kucuk O, et al. Phase II randomized clinical trial of lycopene supplementation before radical prostatectomy. Cancer Epidemiol Biomarkers Prev 2001;10:861-8.
4. Van Breemen RB, et al. Liquid chromatography-mass spectrometry of cis- and all-trans-lycopene in human serum and prostate tissue after dietary supplementation with tomato sauce. J Agric Food Chem 2002;50:2214-9.
5. Silbert JE. Glycosaminoglycans and proteoglycans of skin. In: Fitzpatrick TB, et al., eds. Dermatology in General Medicine, 3rd ed. New York: McGraw-Hill, 1987:314-21.
6. Friedman PM, et al. Safety data of injectable nonanimal stabilized hyaluronic acid gel for soft tissue augmentation. Dermatol Surg 2002;28:491-4.
7. Gebauer K, et al. Topical diclofenac in hyaluronan gel for the treatment of solar keratoses. Australas J Dermatol 200344:40-3.
8. Hong SW, et al. Purification and characterization of novel chondroitin ABC and AC lyases from Bacteroides stercoris HJ-15, a human intestinal anaerobic bacterium. Eur J Biochem 2002;269:2934-40.
9. Girard N, et al. Human monocytes synthesize hyaluronidase. Br J Haematol 2002;119:199-203.
10. Kuhn AV, et al. Identification of hyaluronic acid oligosaccharides by direct coupling of capillary electrophoresis with electrospray ion trap mass spectrometry. Rapid Commun Mass Spectrom 2003;17:576-82.
11. Bernstein EF, et al. Glycolic acid treatment increases type I collagen mRNA and hyaluronic acid content of human skin. Dermatol Surg 2001;27:429-33.