Written by Greg Arnold, DC, CSCS. Twenty-five patients with high cholesterol, consuming walnut and walnut-flaxseed diets, saw a significant improvement in blood pressure and blood flow.
The Center for Disease Control estimates that 1 out of every 3 U.S. deaths is due to cardiovascular diseases, including heart disease and stroke. In 2006, 151,000 of all Americans who died of cardiovascular diseases were younger than age 65, with heart disease and stroke currently disabling nearly 3 million Americans. The cost of cardiovascular diseases in the United States is estimated to be more than $503 billion in 2010 (1).
One of the simplest ways to help maintain heart health is nut consumption. In 2003, the FDA approved a health claim for walnuts and heart disease (2) and another for nuts overall and heart disease (3). This health claim states that ‘‘scientific evidence suggests but does not prove that eating 1.5 oz (42 grams) per day of most nuts, such as [name of specific nut], as part of a diet low in saturated fat and cholesterol may reduce the risk of heart disease.”
Now a new study (4) has again found that walnuts, and now flaxseed, may help with heart health in dealing with stress. In the study, 25 patients with diagnosed high cholesterol (between 201 and 240 mg/dL) and no history of cardiovascular disease consumed one of three diets for 6 weeks:
- Average American Diet (8.7% of calories from polyunsaturated fatty acid (7.9% linoleic acid, 0.8% alpha linolenic acid)
- Linoleic Acid (Walnut Only) Diet (Average American Diet but with reduced saturated fat and 16.4% of calories from polyunsaturated fatty acids (12.6% Linoleic acid, 3.6% alpha-linolenic acid)). In this diet, patients consumed 37 grams of walnuts and 15 grams of walnut oil per day.
- Alpha Linolenic Acid (Walnut-Flaxseed) Diet (Average American Diet but with reduced saturated fat and 17% of calories from polyunsaturated fatty acids (10.5% linoleic acid, 6.5% alpha linolenic acid)). In this diet, patients consumed the above walnut amounts as well as 19 grams of flaxseed oil per day.
Twelve of the 20 patients also had a test called “flow mediated dilatation” to measure blood vessel function, which is recognized as an independent risk factor for the development of CVD (5).
For the stress component, researchers used 2 stress tasks that have been used reliably in previous research (6, 7). After a 30-minute “resting period” to establish a baseline, patients underwent a speech stressor for 5 minutes followed by 10 minutes of recovery and then immersion in a cold foot bath (39 degrees Fahrenheit) for 2.5 minutes. The speech stressor consisted of participants delivering a prepared (2-minute) and then impromptu (3-minute) speech on a hypothetical disagreement (e.g., being falsely accused of shoplifting). Speech topics were changed at the second and third visits. The researchers then took blood pressure 3 times, as well as drawing blood to measure stress responses.
The researchers found that both the walnut and flax diet “significantly reduced” diastolic blood pressure (2-3 mmHg decrease in both groups) compared to no change in the placebo group (p<0.001). Flow-mediated dilatation in the walnut-only and walnut-flaxseed groups was 10% and 34% higher than the placebo group, respectively (p<0.05). The researchers believed that these improvements in the walnut-only and the walnut-flaxseed groups were due in part to an increase of a hormone called arginine-vasopressin (17% higher than placebo in the walnut-flaxseed group and 10% higher than placebo in the walnut-only group) (p<0.05).
For the researchers, “These results suggest novel mechanisms for the cardioprotective effects of walnuts and flax” but that “further work is needed to identify the bioactives responsible for these effects.”
Source: Sheila G West PhD, Andrea Likos Krick PhD, Laura Cousino Klein PhD, Guixiang Zhao PhD, Todd F Wojtowicz JD, Matthew McGuiness MD, Deborah M Bagshaw BS, Paul Wagner BS, Rachel M Ceballos PhD, Bruce J Holub PhD & Penny M Kris-Etherton PhD, RD, FACN (2010) Effects of Diets High in Walnuts and Flax Oil on Hemodynamic Responses to Stress and Vascular Endothelial Function, Journal of the American College of Nutrition, 29:6, 595-603, DOI: 10.1080/07315724.2010.10719898
© Journal of the American College of Nutrition
Posted April 7, 2014.
Greg Arnold is a Chiropractic Physician practicing in Danville, CA. You can contact Dr. Arnold directly by emailing him at PitchingDoc@msn.com or visiting his web site at www.PitchingDoc.com
References:
- “Heart Disease and Stroke Prevention” – posted on the Centers for Disease Control and Prevention website.
- Office of Nutritional Products, Labeling and Dietary Supplements, Food and Drug Administration. Qualified health claims: letter of enforcement discretion – walnuts and coronary heart disease [Docket No. 02P20292] March 9, 2004.
- Office of Nutritional Products, Labeling and Dietary Supplements, Food and Drug Administration. Qualified health claims: letter of enforcement discretion—nuts and coronary heart disease [Docket No 02P20505] July 14, 2007.
- West SG. Effects of diets high in walnuts and flax oil on hemodynamic responses to stress and vascular endothelial function. Jour Amer Coll Nutr Oct 2010
- Yeboah J. Brachial flow-mediated dilation predicts incident cardiovascular events in older adults: the Cardiovascular Health Study, Circulation 115 (2007), pp. 2390–2397
- Everson SA, Lynch JW, Ka pla n GA, Lakka TA, Sivenius J, Salonen JT: Stress-induced blood pressure reactivity and incident stroke in middle-aged men. Stroke 2001;32:1263-70.
- Gianaros PJ. Is cardiovascular reactivity associated with atherosclerosis among hypertensives? Hypertension 2002;40:742-7.
