All Posts tagged antioxidant

Pecans Can Prevent Heart Disease

A new research study from Loma Linda University (LLU) demonstrates that naturally occurring antioxidants in pecans may help contribute to heart health and disease prevention; the results were published in the January 2011 issue of The Journal of Nutrition.

Pecans contain different forms of the antioxidant vitamin E — known as tocopherols, plus numerous phenolic substances, many of them with antioxidant abilities. The nuts are especially rich in one form of vitamin E called gamma-tocopherols. The findings illustrate that after eating pecans, gamma-tocopherol levels in the body doubled and unhealthy oxidation of LDL (bad) cholesterol in the blood decreased by as much as 33 percent. Oxidized LDLs may further contribute to inflammation in the arteries and place people at greater risk of cardiovascular problems. “Our tests show that eating pecans increases the amount of healthy antioxidants in the body,” says LLU researcher Ella Haddad, DrPH, associate professor in the School of Public Health department of nutrition. “This protective effect is important in helping to prevent development of various diseases such as cancer and heart disease.”

These findings are from a research project designed to further evaluate the health benefits of pecans, according to Dr. Haddad. She analyzed biomarkers in blood and urine samples from study participants (a total of 16 men and women between the ages 23 and 44) who ate a sequence of three diets composed of whole pecans, pecans blended with water, or a control meal of equivalent nutrient composition. The pecan meals contained about three ounces of the nut. Samples were taken prior to meals and at intervals up to 24 hours after eating. Following the test meals composed of whole pecans and blended pecans, researchers found that amounts of gamma-tocopherols (vitamin E) in the body doubled eight hours after both meals, and oxygen radical absorbance capabilities (ORAC — a scientific method for measuring antioxidant power in the blood) increased 12 and 10 percent respectively two hours after the meals. In addition, following the whole-pecan meal, oxidized LDL cholesterol decreased by 30 percent (after 2 hours), 33 percent (after 3 hours), and 26 percent (after 8 hours).

“This study is another piece of evidence that pecans are a healthy food,” says Dr. Haddad. “Previous research has shown that pecans contain antioxidant factors. Our study shows these antioxidants are indeed absorbed in the body and provide a protective effect against diseases.” Research from Loma Linda University published earlier in the Journal of Nutrition showed that a pecan-enriched diet lowered levels of LDL cholesterol by 16.5 percent — more than twice the American Heart Association’s Step I diet, which was used as the control diet in that study. Similarly, the pecan-enriched diet lowered total cholesterol levels by 11.3 percent (also twice as much as the Step I diet).

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Antioxidants lower stroke risk

Eating a diet high in antioxidants may protect against ischemic stroke, an Italian cohort study showed.

People who had a diet high in total antioxidant capacity — an index that takes into account several different antioxidants and their interactions — had a 59% reduced relative risk of ischemic stroke (HR 0.41, 95% CI 0.23 to 0.74), according to Nicoletta Pellegrini, PhD, of the University of Parma in Italy, and colleagues. But there was no such relationship with hemorrhagic stroke, they reported in the January issue of the Journal of Nutrition. In fact, the highest intake of the antioxidant vitamin E was associated with a greater risk of hemorrhagic stroke (HR 2.94, 95% CI 1.13 to 7.62).
Considering evidence suggesting that oxidative stress and systemic inflammation are involved in the pathogenesis of ischemic stroke, the researchers noted that “a high-total antioxidant capacity diet could be protective as a consequence of its ability to deliver compounds with antioxidant activity and with a demonstrated anti-inflammatory effect.” But, they acknowledged that the mechanism for such activity was unclear may “go beyond the antioxidant activity of the numerous total antioxidant capacity contributors present in foods and beverages.”

Pellegrini and her colleagues set out to explore the relationship between dietary total antioxidant capacity and the risk of stroke among 41,620 people participating in EPICOR, the Italian segment of the European Prospective Investigation into Cancer and Nutrition (EPIC). None had a history of stroke or MI at baseline. Dietary intake was assessed with a food frequency questionnaire. In the study population, more than half of the total antioxidants consumed came from coffee, wine, and fruit. Through a mean follow-up of 7.9 years, there were 112 ischemic strokes, 48 hemorrhagic strokes, and 34 other types of strokes. After adjustment for energy intake, hypertension, smoking status, education, nonalcoholic energy intake at recruitment, alcohol intake, waist circumference, body mass index, and total physical activity, individuals eating a diet in the highest tertile of total antioxidant capacity had a reduced risk of ischemic — but not hemorrhagic — stroke.

Looking at individual antioxidants, the researchers found that participants consuming the highest amounts of vitamin C had a reduced risk of ischemic stroke (HR 0.58, 95% CI 0.34 to 0.99). Controlling for vitamin C intake did not negate the overall association between antioxidants and ischemic stroke, which ruled out the nutrient as the sole driver of the relationship. High intake of vitamin E, on the other hand, was associated with nearly triple the relative risk of hemorrhagic stroke. However, “it must be stressed that the small number of cases observed in this population strongly limits the validity of statistical observations on hemorrhagic stroke,” noted the researchers, who called for further studies.

Aside from anti-inflammatory effects, it is possible that the association between antioxidants and ischemic stroke risk can be explained by the interaction between polyphenols — the major contributors to total antioxidant capacity — and the generation of nitric oxide from the vascular endothelium. That interaction leads to the vasodilation and expression of genes that may be protective for the vascular system, according to the researchers. In addition, coffee — the main source of antioxidants in the study population — reduces blood pressure, which is a recognized risk factor for ischemic stroke, the researchers wrote.

They noted some limitations of the study, including the low numbers of cases when different types of stroke were analyzed, the measurement of total antioxidant capacity at baseline only, and the inability to rule out confounding effects of other dietary components, like sodium and potassium.

Source: Del Rio D, et al “Total antioxidant capacity of the diet is associated with lower risk of ischemic stroke in a large Italian cohort” J Nutr 2011; 141: 118-123.

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Effects of Grapefruit on Diabetes

Recent studies show that grapefruit and diabetes may share a close link. Researchers concluded that naringenin found in grapefruit may increase the body's sensitivity to insulin. This research was conducted only in the laboratory, and further studies are still needed. Grapefruit and diabetes may share a close link given some recent studies suggesting that eating of the fruit can help in controlling the disease. One recent report suggests that grapefruit may become an effective part of the treatment for type 2 diabetes as it contains the antioxidant Naringenin that can break down fats and increase a person's sensitivity to insulin.

The study also concluded that grapefruit is also capable of treating abnormal levels of cholesterol, warding off metabolic syndrome and improving a person's tolerance to glucose, factors that are all associated with diabetes. The study was conducted by scientists from the Massachusetts General Hospital Center for Engineering in Medicine and Hebrew University of Jerusalem. Although more research needs to be completed, grapefruit is a safe source of vitamins for diabetics. One-half of a grapefruit contains 52 calories and 13g of carbohydrates, and the fruit has a low rating on the glycemic index, indicating a lower propensity to drive up blood sugar levels.

Research

The antioxidant Naringenin is found in grapefruit and has been largely credited for its ability in heping to treat type 2 diabetes. Naringenin is specifically noted for being able to break down fatty acids in the liver, similar to what happens when a person undergoes fasting. Yaakov Nahmias, PhD of the Hebrew University of Jerusalem reports that the results of their study indicate that Naringenin antioxidant was found to be capable of breaking down fatty acids similar to those induced by significant amounts of fasting. It does so by activating nuclear receptors, a family of proteins that can cause the liver to break down fatty acids instead of storing them.

Another study conducted by researchers at the University of Western Ontario showed that Naringenin can correct increases in triglyceride and cholesterol levels, while resisting insulin resistance and normalizing glucose metabolism. The said study showed that Naringenin genetically reprograms the liver to burn up more excess fat, instead of storing it. The said study also showed that Naringenin is able to suppress appetite and decrease food intake, which are common strategies in controlling diabetes.

The study of MGH and Hebrew University scientists also noted that Naringenin can lower bad cholesterol called vLDL while able to cure several symptoms of type 2 diabetes.

Remains Unproven

Research on grapefruit and diabetes, however, has not yet been conducted on humans, and were only done in the laboratory on the liver cells of humans and rats. Until further studies are done to confirm the effects of grapefruit in the treatment of diabetes type 2 in humans, it is still not safe to conclude that the naringenin in grapefruits can indeed cure diabetes. Further studies are still needed to establish its efficacy as well as its overall effects in the body, including the negative effects it might have.

Thus, many health experts do not encourage patients with diabetes to increase their consumption of grapefruits or increase grape juice intake, especially if they are also taking medications. There are patients prescribed with some type of drugs to lower their cholesterol level who are advised not to drink grapefruit juice as it can increase risk of side effects.

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Spicing the Meat Reduces Cancer Risk

Applying spices to beef not just enhances its taste but can also cut down your risk of cancer, suggests a new study. J. Scott Smith, a Kansas State University food chemistry professor, has pursued different projects in recent years seeking ways to reduce heterocyclic amines (HCAs).

HCAs are the carcinogenic compounds that are produced when muscle foods, such as ground beef patties, are barbecued, grilled, boiled or fried. Consuming HCAs through meat increases risk factors for colorectal, stomach, lung, pancreatic, mammary and prostate cancers.

In a research, Smith found that certain spices containing natural antioxidants would reduce HCA levels by 40 percent when applied to beef patties during cooking.

“Cooked beef tends to develop more HCAs than other kinds of cooked meats such as pork and chicken. Cooked beef patties appear to be the cooked meat with the highest mutagenic activity and may be the most important source of HCAs in the human diet,” Smith said.

Previous studies have shown that meat products cooked below 352 degrees Fahrenheit for less than four minutes had low or undetectable levels of HCAs, with HCAs increasing with higher temperatures and added cooking time. It's not a good idea to lower cooking temperatures too much, so antioxidant spices with phenolic compounds can block HCAs before they form during heating and still allow high temperatures to be maintained.

Smith's research team investigated six spices – cumin, coriander seeds, galangal, fingerroot, rosemary and tumeric – and found that the latter three had the highest levels of antioxidant activity toward inhibiting the formation of HCAs, with rosemary as the most effective.

Consumers can take advantage of the spices by integrating them into their cooking regimen. Previous research in his laboratory has demonstrated that some commercial rosemary extracts, available for purchase on the Internet, can inhibit HCA formation by 61 to 79 percent. Smith's earlier work also showed that Thai spices can inhibit HCA formation by 40 to 43 percent.

Smith said future research in this area will investigate what some marinades or powders can do to inhibit HCAs when applied to a cooked patties. His earlier project showed that marinating steaks with certain herbs, rosemary and other antioxidant spices also reduces HCAs.

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