Nutty Buddy
Trying to crush them can be enough to send you over the edge, but can eating walnuts actually protect your heart?
According to a new study (presented at the American Heart Association's 5th Annual Conference on Arteriosclerosis, Thrombosis, and Vascular Biology) daily walnut consumption may improve vascular function and lower LDL cholesterol. A closer look at the study reveals that the heart protection value of walnuts is probably due to one key nutrient that's also available in other foods. And while this nutrient - an antioxidant and an important source of essential fatty acids - is clearly beneficial, supplementing with it poses a potential drawback for those who tend to have low blood sugar or type 1 diabetes.
Shelia G. West, Ph.D., the lead author of the new study, told researchers at the American Heart Association conference that she and her team at Pennsylvania State University (PSU) wanted to determine if plant-based alpha- linolenic acid (ALA; a precursor of omega-3 fatty acids) would provide clear cardiovascular benefits. Thirteen subjects (each with high cholesterol) were chosen to eat three different diets. Each diet lasted six weeks, with a two-week break between dieting periods. The PSU team prepared all meals for the subjects, and one meal each day was eaten with the researchers. The three diets: - The Average American Diet (AA) contained the fat content and calories of a typical U.S. diet
- The High Dose ALA Diet (HD) contained the same amount of total fat as the AA diet, but was low in saturated fat and cholesterol, and high in ALA.
- The Linoleic Acid Diet (LA) was the same as the HD diet, but balanced ALA content with linoleic acid, another omega- 3 fatty acid.
At the end of each dieting period, each subject had their cholesterol levels and flow-mediated dilation (FMD) measured. FMD reveals blood vessel resiliency to change in blood flow. Arteries are more responsive (and healthier) when FMD measurements are high. Researchers found that cholesterol levels improved after subjects changed from the AA diet to one of the other diets. But vascular function was boosted only with the HD diet. When ALA was the most abundant fat type, the FMD level was improved by more than a third over the typical American diet.
The PSU trial was funded by the California Walnut Commission, so naturally the plant-based ALA source in the HD and LA diets both came from walnuts, which provided the total fat in those diets: A little over an ounce of walnuts and about half an ounce of walnut oil daily. I don't mind putting in a good word for the walnut commissioners of California because walnuts offer excellent nutrition. In the e-Alert "The Fix is In" (7/22/03), I told you that in addition to the high omega-3 content, walnuts also deliver vitamins (including vitamin B-6 and folate), minerals, protein, fiber, and melatonin. But if it's specifically ALA you're after, there are a number of other good sources. Flaxseed is very high in ALA content, as is flaxseed oil, leafy green vegetables, pumpkin seeds, and wheat germ oil.
The benefits of alpha-linolenic acid are not new to HSI members. In both e-Alerts and Members Alerts we've told you about the unique ability of ALA to actually recycle vitamins C and E from their molecular building blocks - something that no other antioxidant is known to do. In addition, ALA can help your body better utilize other antioxidants such as coenzyme Q10 and glutathione. Several studies have concluded that a daily intake of 50 mg of ALA may yield significant benefits. Unfortunately, ALA is quickly metabolized and cleared from the liver. So whether you supplement with ALA, or if you munch on walnuts or flaxseeds, it's best to spread the intake throughout the day, rather than getting it all at once. ALA also been shown to be a blood-sugar-lowering agent for type 2 diabetics. But the effect of ALA on those who suffer from hypoglycemia (low blood sugar) has not been specifically studied, so ALA should probably not be used by those with very low blood sugar. As always, it's a good idea to discuss your supplement intake with your doctor or healthcare provider. And in the case of ALA this is especially important if you're diabetic, or if low blood sugar is an issue. To Your Good Health, Jenny Thompson
Health Sciences Institute Sources:
"Plant-Based Omega-3 Fats may Help Artery Function" The American Heart Association's 5th Annual Conference on Arteriosclerosis, Thrombosis, and Vascular Biology, Meeting Report, 5/6/04, americanheart.org
"Nuts about Cardiovascular Health" NutraIngredients.com, 5/13/04, nutraingredients.com
"Should You Give Up Nuts, Steak - or Both? Try Neither!" William Campbell Douglass, M.D., Real Health newsletter, 8/1/02, realhealthnews.com
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