Compound From Olive Fruit Shows Heart Health Potential

New research shows portion-controlled meal replacement diets as more effective than standard diets at both initial weight loss and long-term weight maintenance in type 2 diabetics.
In a recent study, supplementing with hydroxytyrosol – a polyphenolic compound extracted from olives – correlated with higher activity levels of the enzyme arylesterase, an antioxidant biomarker, and lower levels of oxidized LDL cholesterol. Oxidized LDL is believed to be a major player in promoting atherosclerosis (the build-up of fatty plaques in arteries) and general cardiovascular disease.

Hydroxytyrosol is thought to be the main antioxidant compound in olive fruit, and it is believed to play a significant role in many of the health benefits attributed to olive oil. Previous research has linked the compound to cardiovascular benefits, typically reductions in LDL or “bad” cholesterol. Data has also suggested the compound may boost eye health and reduce the risk of macular degeneration.

Spanish researchers reported these most recent results in the British Journal of Nutrition. Twenty-two healthy volunteers between 20 and 45 years of age and with a BMI between 18 and 33 kg/m2 were recruited. Volunteers were randomly assigned to receive 10 to 15 grams per day of hydroxytyrosol-enriched sunflower oil or non-enriched sunflower oil for three weeks. The former provided a daily hydroxytyrosol dose of between 45 and 50 mg. After the initial three week period, volunteers had two weeks of no intervention before crossing over to receive the other intervention.

Results showed no changes in total, LDL, or HDL-cholesterol between the groups. However, consumption of the hydroxytyrosol-enriched sunflower oil produced significant reductions in oxidized LDL from 79.8 units per liter at the start of the study to 64.1 U/l after three weeks, compared to an increase from 72.7 to 86.4 U/l during the control phase. Furthermore, the activity of arylesterase increased from 235.2 to 448.9 U/l during the hydroxytyrosol phase, compared with an increase from 204.1 to 310.3 U/l during the control phase.

The researchers reported that although hydroxytyrosol-enriched sunflower oil did not significantly reduce LDL-cholesterol or increase HDL-cholesterol, it acted as a functional food by increasing arylesterase activity and reducing oxidized LDL. Based on these results, dietary sources of hydroxytyrosol appear to be capable of reducing certain risk factors associated with coronary artery disease.

Vazquez-Velasco M, et al. Effects of hydroxytyrosol-enriched sunflower oil consumption on CVD risk factors. 2010. Br J Nutr, ePub ahead of print. doi: 10.1017/S0007114510005015

Meal Replacements Better Than Standard Diets for Weight Loss in Diabetics

New research shows portion-controlled meal replacement diets as more effective than standard diets at both initial weight loss and long-term weight maintenance in type 2 diabetics.

A recent study published in Diabetes Education compared the efficacy of a portion-controlled meal replacement diet (PCD) to a standard diet (SD) based on American Diabetes Association recommendations in achieving and maintaining weight loss.

Participants included 119 overweight men and women with type 2 diabetes and a body mass index (BMI) between 25 and 40. Subjects were randomly assigned to one of two diets (PCD or SD) that contained 75% of predicted energy needs. The diets were then followed by a maintenance phase of one year.

Weight loss at 34 weeks and weight maintenance at 86 weeks was significantly better on PCD versus SD. Approximately 40% of the PCD participants lost at least 5% of their initial weight compared with only 12% of those on the standard diet. Significant improvements in biochemical and metabolic measures were observed at 34 weeks in both groups. The ease and self-reported adherence to the diet were greater in the PCD group throughout the study.

In this study, a diet using portion-controlled meal replacements resulted in significantly greater initial weight loss and less regain after one year of maintenance than a standard, self-selected, food-based diet. As PCDs may help obese patients with type 2 diabetes adhere to a weight control program, diabetes educators should consider recommending them as part of a comprehensive approach to weight control.

Recommended healthy diet USANA RESET

Cheskin LJ, et al. Efficacy of meal replacements versus a standard food-based diet for weight loss in type 2 diabetes: a controlled clinical trial. 2008. Diabetes Educ 34(1):118-27

High Glycemic Load Diets Increase Risk of Age-Related Hearing Loss

In a recent study of adults over 50 years old, those with a high glycemic load diet had a significantly increased risk of age-related hearing loss.

Age-related hearing loss is a common disability in older adults, and nutrition may play a role in the development of this condition. Carbohydrate nutrition is thought to possibly relate to age-related hearing loss.

In a recent issue of the Journal of Nutrition, researchers sought to determine the association between glycemic index (GI) and glycemic load (GL) and age-related hearing loss.

Hearing loss was measured in 2956 participants aged 50 years or older enrolled in the Blue Mountains Hearing Study. Food frequency questionnaires were used to document intakes of carbohydrates, sugar, starch, cereal and total fiber. Australian GI values were used to calculate average GI and GL values of the diets.

A higher average dietary GI was associated with a 59% increased prevalence of any hearing loss. Participants in the highest 25% of average dietary GL intake compared with those in the lowest 25% had a 76% greater risk of developing hearing loss. Higher carbohydrate and sugar intakes were also associated with occurrence of hearing loss.

In this study group, a high-GL diet was a predictor of hearing loss, as was higher intake of total carbohydrates. It is possible that prolonged high blood glucose levels after a meal may be an underlying biological mechanism in the development of age-related hearing loss.

Gopinath B, et al. Dietary Glycemic Load Is a Predictor of Age-Related Hearing Loss in Older Adults. 2010. J Nutr 140(12):2207-12.

High Protein, Low-Glycemic Diets Better at Maintaining Weight Loss

New research shows that a low-glycemic diet relatively high in protein is more effective at weight maintenance than a low-protein, high-glycemic diet.

A recent study in the New England Journal of Medicine reports that a diet relatively high in protein and low in refined carbohydrates (low-glycemic) is more successful than other diets at maintaining weight loss.

Researchers enrolled overweight adults from eight European countries who had lost at least 8% of their initial body weight with a low-calorie diet. Participants were randomly assigned to one of five diets to prevent weight regain over a 26-week period: a low-protein and low-GI (glycemic index) diet, a low-protein and high-GI diet, a high-protein and low-GI diet, a high-protein and high-GI diet, or a control diet based on the current European dietary recommendations. The high protein diet provided 25 percent of calories in the form of protein, while the low protein diet consisted of 13 percent protein.

Five hundred forty-eight subjects completed six months on the assigned diets. In the analysis of participants who completed the study, only the low-protein/high-GI diet was associated with subsequent significant weight regain (1.67 kg, or 3.6 lbs) by the end of the dietary intervention. Weight regain was less in those who consumed high protein compared to low protein and in low-GI diets compared to high-GI diets. High-GI foods include white flour, white rice, and other refined carbohydrates.

This study shows that a modest increase in protein content and a modest reduction in glycemic index can lead to an improvement in compliance and maintenance of weight loss.

Larsen TM, et al. Diets with High or Low Protein Content and Glycemic Index for Weight-Loss Maintenance. 2010. N Engl J Med 363:2102-13.

Low Vitamin D Levels May Increase Heart Disease Risk

A study published in the journal Circulation showed that low levels of vitamin D may increase the risk of cardiovascular events, including heart attack, heart failure, or stroke. Individuals with both hypertension and low vitamin D levels had nearly double the risk of cardiovascular problems.

Interest in vitamin D has been increasing in recent months with a growing number of studies linking the vitamin to protection against osteoporosis and certain cancers. There is also evidence that a higher intake of vitamin D may be helpful with regard to high blood pressure, fibromyalgia, diabetes mellitus, multiple sclerosis, and rheumatoid arthritis

In a population-based study, researchers used data from 1739 participants in the Framingham Offspring Study to study the relationship between vitamin D levels and cardiovascular health risk. Although vitamin D levels above 30 ng/mL are considered optimal for bone metabolism, only 10 percent of the participants had levels in this range. In fact, 28 percent had blood levels lower than 15 ng/mL. Participants with levels below 15 ng/mL had a 62 percent greater chance to develop cardiovascular events than those with higher levels. People with low vitamin D levels and high blood pressure (> 140/90 mmHg), were found to have double the risk of cardiovascular problems compared to people with normal blood pressure and vitamin D levels.

Vitamin D is produced in the skin on exposure to UVB radiation (sunlight) and obtained in the diet from foods like oily fish, egg yolk, and liver. Recent studies have shown, however, that sunshine levels in some northern countries are so weak during the winter months that the human body makes little to no vitamin D, leading to widespread deficiencies. In addition, increased skin pigmentation also reduces the effect of UVB radiation, meaning darker skinned people are at greater risk.

The results from this study raise the possibility that treating vitamin D deficiency, by supplementation and/or lifestyle measures, could reduce the risk of cardiovascular events.

Wang TJ, et al. Vitamin D Deficiency and Risk of Cardiovascular Disease. 2008. Circulation 117(4):503-11