Walnuts were introduced to the Americas by Spanish explorers in the 1700s¹ and are now the second largest nut crop produced in the U.S. (second only to almonds). Walnuts have been found to help control blood sugar levels² and promote both eye health³ and blood vessel health⁴.

 

Now a new study⁵ has found that walnuts may benefit prostate health.  This is due to walnuts’ high content of vitamin E:  75 grams of walnuts contain 0.52 mg of alpha-tocopherol and 15.6 mg of gamma-tocopherol⁶, which have been shown to inhibit growth of prostate tumor cells^{(7, 8, 9)}.  Walnuts also contain ellagic acid¹⁰, which has been shown to effectively induce programmed cell death (called “apoptosis”) and inhibit blood vessel formation^{(11, 12)} that is a hallmark of the progression of cancer.

 

Prostate cancer is the second most deadly cancer in men (lung cancer is the number one killer¹³, killing nearly 31,000 men in 2002¹⁴ and producing 234, 460 new cases and over 27,000 deaths in 2006¹⁵.  In the study, two groups of patients consumed 2,000 calories.  One group had 75 grams of walnuts (comprising 24% of their daily calories) and the control group followed the “Average American Diet” for 8 weeks.  After this period, they stopped for two weeks and then switched to follow the other group’s diet for 8 more weeks. 

 

The researchers found that while no significant improvements were seen in alpha-tocopherol blood levels, patients in the walnut group had gamma-tocopherol blood levels that were three times higher than the control group.  This increase led to an alpha/gamma tocopherol ratio, found in previous research to be related to prostate health¹⁶, that was nearly seven times lower in the walnut group than the placebo group.

 

Citing the aforementioned vitamin E research as well as other research showing vitamin E to “hold promise in decreasing risk of prostate cancer^{(17, 18)}, the researchers concluded that “the significant decrease in [alpha-tocopherol:gamma-tocopherol ratio] (without changes in body weight) in response to incorporation of 75 grams of walnuts per day in the diet offers the promise of significant benefits for both vascular and prostate health.”

 

In addition to walnuts, there are a number of other ways to help maintain prostate health, including green tea¹⁹, flaxseed²⁰, soy²¹, and vitamin E²², as well as lifestyle choices, such as getting more exercise²³ and minimizing starchy food intake²⁴.

 

Greg Arnold is a Chiropractic Physician practicing in Danville, CA.  You can contact Dr. Arnold directly by emailing him at mailto:PitchingDoc@msn.com or visiting his web site at www.CompleteChiropracticHealthcare.com

 

Reference:

 

¹  “Commodity Highlights: Walnuts” posted on the USDA Website http://www.usda.gov

 

²  Gillen LJ.  Structured dietary advice incorporating walnuts achieves optimal fat and energy balance in patients with type 2 diabetes mellitus. J Am Diet Assoc. 2005 Jul;105(7):1087-96

 

³  Progression of age-related macular degeneration: association with dietary fat, transunsaturated fat, nuts, and fish intake.  Arch Ophthalmol. 2003 Dec;121(12):1728-37

 

⁴  Cortes B.  Acute Effects of High-Fat Meals Enriched With Walnuts or Olive Oil on Postprandial Endothelial Function.  Jou Am Coll Cardiol 2006; 48(8):1666-1671

 

⁵  Spaccarotella KJ.  The effect of walnut intake on factors related to prostate and vascular health in older men.  Nutr J 2008;7:13

 

⁶  National Nutrient Database for Standard Reference http://www.ars.usda.gov/main/main.htm

 

⁷  Israel K, Sanders B, Kline K: RRR-alpha-tocopheryl succinate inhibits the proliferation of human prostatic tumor cells with defective cell cycle/differentiation pathways. Nutr Cancer 1995, 24:161-169.

 

⁸  Sigounas G, Anagnostou A, Steiner M: dl-alpha-tocopherol induces apoptosis in erythroleukemia, prostate, and breast cancer cells. Nutr Cancer 1997, 28:30-35.

 

⁹  Gysin R, Azzi A, Visarius T: Gamma-tocopherol inhibits human cancer cell cycle progression and cell proliferation by down-regulation of cyclins. FASEB J 2002, 16:1952-1954.

 

¹⁰  Daniel E: Extraction, stability, and quantitation of ellagic acid in various fruits and nuts. J Food Compos Anal 1989, 2:338-349

 

¹¹  Narayanan B, Geoffroy O, Willingham M, Re G, Nixon D: p53/p21(WAF1/CIP1) expression and its possible role in G1 arrest and apoptosis in ellagic acid treated cancer cells. Cancer Lett 1999, 136:215-221.

 

¹²  Labrecque L.  Combined inhibition of PDGF and VEGF receptors by ellagic acid, a dietary-derived phenolic compound. Carcinogenesis 2005, 26:821-826.

 

¹³  National Vital Statistics Report Volume 53, Number 5, released October 12, 2004

 

¹⁴  “What Are The Key Statistics For Prostate Cancer?” posted on the American Cancer Society Website  www.cancer.org/docroot/CRI/content/CRI_2_4_1X_What_are_the_key_statistics_for_prostate_cancer_36.asp?sitearea=

 

¹⁵  ”The Prostate-Specific Anigen (PSA) Test: Questions and Answers” posted on www.cancer.gov/cancertopics/factsheet/detection/PSA

 

¹⁶  Lemcke-Norojärvi M, Kamal-Eldin A, Appelqvist L, Dimberg L, Ohrvall M, Vessby B. Corn and sesame oils increase serum gamma-tocopherol concentrations in healthy Swedish women. J Nutr. 2001;131:1195–1201.

 

¹⁷  Chan J.  Plasma insulin-like growth factor-I and prostate cancer risk: a prospective study. Science 1998, 279:563-566.

 

¹⁸  Helzlsouer K.  Association between alpha-tocopherol, gamma-tocopherol, selenium, and subsequent prostate cancer. J Natl Cancer Inst 2000, 92:2018-2023.

 

¹⁹  “Green tea shown to prevent prostate cancer” posted on www.medicalnewstoday.com/articles/23190.php

 

²⁰  Demark-Wahnefried W.  Pilot study of dietary fat restriction and flaxseed supplementation in men with prostate cancer before surgery: exploring the effects on hormonal levels, prostate-specific antigen, and histopathologic features.  Urology 2001 Jul;58(1):47-52

 

²¹  Hedelin M.  Dietary Phytoestrogen, Serum Enterolactone and Risk of Prostate Cancer: The Cancer Prostate Sweden Study.  Cancer Causes and Control 2006; 17(2): 169-180

 

²²  Srivastava  JK.  Tocotrienol-rich fraction of palm oil induces cell cycle arrest and apoptosis selectively in human prostate cancer cells.  Biochm Biophys Res Comm 2006; 346(2): 447-453

²³  Giovannucci, E. L., Y. Liu, et al. (2005). "A prospective study of physical activity and incident and fatal prostate cancer." Arch Intern Med 165(9): 1005-10 

 

²⁴  Bidoli, E., R. Talamini, et al. (2005). "Macronutrients, fatty acids, cholesterol and prostate cancer risk." Ann Oncol 16(1): 152-7