Reduction in Oxidation Damage to DNA

by | May 6, 2010 | 2010, Cardiovascular Health, Metabolic Syndrome, Nuts and Seeds

Written by Jessica Patella, ND. A study of 50 adults with metabolic syndrome showed that the group who consumed 30 g of nuts daily over a 12 week period had a significant reduction in DNA damage compared to the control group.

Many have heard the cliché, you are what you eat, but could science prove it through DNA?  Recent research indicates that positive changes to DNA can be correlated to eating mixed nuts daily (1).

Nuts have many beneficial components.  They contain antioxidants, which have been shown in many studies to decrease damage to fats and proteins in the body and slow the progression of atherosclerotic plaque (2).  Atherosclerotic plaque is one of the main components of cardiovascular disease; for this reason, many dietary guidelines worldwide are now recommending regular consumption of nuts in the diet (3).

In a recent study, fifty males and females with Metabolic Syndrome, were randomly assigned to a control group or a group consuming nuts. Metabolic Syndrome is defined as having at least three of the following criteria: (a) waist circumference of greater than or equal to 102 cm for men and 88 cm for women, (b) triglycerides of greater than or equal to 1.7 mmol/L, (c) HDL cholesterol levels less than 0.9 mmol/L in men and 1.1 mmol/L in women, (d) elevated systolic blood pressure of 130 mm Hg or elevated diastolic blood pressure of 85 mm Hg, and (e) fasting glucose of greater than or equal to 100mg/dL or on drug treatments for any of the above.

The group consuming nuts were given 30 g (about one ounce) of mixed raw nuts with skin (15g walnuts, 7.5g almonds, 7.5g hazelnuts) daily. Both groups were given diet recommendations to follow a similar overall diet, with the only difference being the consumption of mixed nuts, over a 12-week period. Adherence to the diet was measured by counting empty packages of nuts, as well as, both groups filling in a 3-day food record every 4 weeks (1).

Participants in both groups lost weight, approximately 3 pounds in the control group and approximately 5 pounds in the nut group.  There were no significant changes in body mass index, systolic or diastolic blood pressure, or any of the lipid profile measurements (total cholesterol, triglycerides, LDL, HDL) in either group. However, the group consuming mixed nuts did have significant (p< 0.001) reduction in DNA damage as measured by 8-oxo-dG (control group change of -3.93 nmol/mmol creatinine and nut group change of -6.35 nmol/mmol creatinine).

Of all the oxidative stress by-products, 8-oxo-dG has been one of the most widely studied (4).  When 8-oxo-dG is present in DNA results, it indicates gene instability and has been related to tumor initiation and growth (5). This is important for cancer growth, degenerative diseases, atherosclerosis and diabetes (1).

In conclusion, daily consumption of mixed nuts (walnuts, almonds, and hazelnuts) is associated with a beneficial effect on DNA, which could explain beneficial effects of regular nut consumption on cardiovascular disease found in other studies (1). This is the first study to evaluate the effect of mixed nuts on several lipid and DNA markers in participants with Metabolic Syndrome (1).

Source: López-Uriarte, Patricia, et al. “Effect of nut consumption on oxidative stress and the endothelial function in metabolic syndrome.” Clinical nutrition 29.3 (2010): 373-380.

© 2009 Elsevier Ltd and European Society for Clinical Nutrition and Metabolism

Posted May 6, 2010.

References:

  1. Lopez-Uriarte, et al. Effect of nut consumption on oxidative stress and the endothelial function in metabolic syndrome.  Clin Nutr. 2010.
  2. Chen CY, Blumberg JB.  Phytochemical composition of nuts.  Asia Pac J Clin Nutr. 2008;17:SS3329-SS3332.
  3. Johnson RK, Kennedy E.  The 2000 guidelines for Americans: what are the changes and why were they made? The dietary guidelines advisory committee.  J Am Diet Assoc 2000;100:769-74.
  4. Valavanidis, et al.  8-hydroxy-2’ –deoxyguanosine (8-OHdG):a critical biomarker of oxidative stress and carcinogenesis.  J Environ Sci Health C Environ Carcinog Ecotocicol Rev 2009;27:120-39.
  5. Oliva MR, et al.  Genetic altherations and oxidative metabolism in sporadic colorectal tumors from a Spanish community.  Mol Carcinog 1997;18:232-43.