Can antioxidants help reduce Alzheimer?s disease risk?
Research suggests antioxidants may protect the aging brain against oxidative damage. Since oxidative stress has been associated with the onset, cause or progression of Alzheimer?s disease, decreasing this free radical attack on the brain is thought to affect the disease. Results of a fairly large, prospective observational study offer some evidence of this relationship. Almost 5,000 elderly men and women were followed for more than five years to assess the amounts of supplemental antioxidant vitamins and minerals they were taking, and Alzheimer?s disease onset. The researchers concluded the use of vitamins C and E together was associated with a reduced incidence of Alzheimer?s disease.1 They stress the combination must be used to have this protective effect. This makes sense because antioxidants do not work in isolation but rather as a group, supporting and replenishing one another. This recent work adds to a body of literature that, for the most part, supports some protective effect of antioxidant supplements (and dietary antioxidants) in age-related cognitive decline. Randomized prevention trials would be the gold standard, but the evidence from the prospective observational study bodes well for the use of these supplemental vitamins long term to deter cognitive decline.
What does the term net carb mean?
It is hard to say. The U.S. Food and Drug Administration does not regulate net carb labeling; therefore, there is no legal definition of the term. In fact, the FDA has sent warning letters to manufacturers who make various low-carbohydrate claims on their products and is in the process of defining these terms. This may take time, though. Many manufacturers are appealing to consumers who are cutting carbohydrates from their diets by using terms such as net carb to refer to the amount of carbohydrate in a product after subtracting other carbohydrates they say have little effect on blood sugar. Thus, carbohydrates such as fiber and sugar alcohols (sorbitol, mannitol and xylitol) are subtracted. This labeling may have some basis, but it is quite confusing and can be misleading. First, a glycemic index rating reflects the true measure of a carbohydrate?s effect on blood sugar. The glycemic index measures a specific amount of a carbohydrate?s ability to raise blood sugar. GI is well studied, and there is a wealth of data on its association with diabetes, obesity and other diseases.2,3,4 Second, net carbs tells you nothing about calories. The term can be misleading because many low-net-carb products have a lot of calories. GI matters, but calories matter as well. It would therefore be much less confusing if companies tested their products by a reproducible standard such as the glycemic index, which allows accurate comparisons.
Is flaxseed oil consumption associated with prostate cancer risk?
Flaxseeds contain high levels of the essential omega-3 fat alpha-linolenic acid. Flaxseed oil is a major source of ALA, but there are various other sources as well, such as beef, nuts and other seeds. The controversy regarding flaxseed consumption and prostate cancer risk started when results of an epidemiological study showed increased prostate cancer rates in men with higher ALA intakes. However, the source of ALA in this study was beef, not flaxseed.5 Researchers concluded that animal fat, especially fat from red meat, was associated with an elevated risk of advanced prostate cancer, and the ALA association needed further study. More recently, researchers conducted an analysis of a large group of men (the Health Professionals Follow-Up Study).6 The results showed intakes of total meat, red meat and dairy products were not associated with total or advanced prostate cancer risk. However, an elevated risk for metastatic prostate cancer was observed with red meat intake. No studies have been done examining the risk of prostate cancer with flaxseed oil consumption. So, although some epidemiological studies have suggested an association between dietary ALA and prostate cancer risk, this is a long way from a cause-and-effect relationship with flaxseed oil. There is no strong evidence that consuming moderate amounts of flaxseed oil would increase prostate cancer risk; however, ALA is a molecule that is easily oxidized, or rancidified. It is conceivable that oxidative byproducts of this fatty acid could be carcinogenic. Therefore, antioxidant support is important when consuming these easily oxidized oils. It seems most likely that the interplay of ALA with other dietary factors, such as antioxidant vitamins and minerals, may influence susceptibility to prostate cancer.7
Dan Lukaczer, N.D., is director of clinical research at the Functional Medicine Research Center, a division of Metagenics Inc., in Gig Harbor, Wash.
1. Zandi PP, et al. Reduced risk of Alzheimer disease in users of antioxidant vitamin supplements: the Cache County Study. Arch Neurol 2004;61(1):82-8.
2. Salmeron J, et al. Dietary fiber, glycemic load, and risk of NIDDM in men. Diabetes Care 1997;20(4):545-50.
3. Hu FB, et al. Diet, lifestyle, and the risk of type 2 diabetes mellitus in women. N Engl J Med 2001;345(11):790-7.
4. Ludwig DS, et al. High glycemic index foods, overeating, and obesity. Pediatrics 1999;103(3):E26.
5. Giovannucci E, et al. A prospective study of dietary fat and risk of prostate cancer. J Natl Cancer Inst 1993;85(19):1571-9.
6. Michaud DS, et al. A prospective study on intake of animal products and risk of prostate cancer. Cancer Causes Control 2001;12(6):557-67.
Natural Foods Merchandiser volume XXV/number 5/p. 45