Mediterranean diet lowers vascular deaths
Nutrients preserve brain function
Does vitamin D reduce mortality?
Walking to help muscles
Red meat increases kidney cancer
Researchers studied the effects of diet on vascular diseases among 2568 participants from Northern Manhattan. They developed a Mediterranean diet score (MeDi score) ranging from 0 to 9, with the higher number indicating closer adherence to a Mediterranean style diet. This diet includes lots of fresh fruits and vegetables, whole grains, beans, fish, and olive oil, and has little meat, dairy, or animal fat.
They followed the subjects for an average of nine years. During that time, there were 518 vascular events, including 171 ischemic strokes, 133 heart attacks, and 314 vascular deaths. The MeDi score was inversely associated with the vascular events, primarily as a result of fewer vascular deaths and fewer heart attacks. In this study they did not find a correlation with ischemic stroke by itself. (Gardener H, et al., Mediterranean-style diet and risk of ischemic stroke, myocardial infarction, and vascular death: the Northern Manhattan Study. Am J Clin Nutr. 2011 Dec;94(6):1458-64.)
Of the subjects in this study, 55 percent were Hispanic, 24 percent were black, and 21 percent were white. The researchers attempted to control for sociodemographic and vascular risk factors. Typically, Hispanics and non-Hispanic blacks have high rates of heart disease, but this is almost certainly related to lifestyle and diet rather than genetics. The ancestral Africans adhering to native diets did not have high rates of these diseases related to industrialized food supplies, so it is difficult to make a case for a genetic connection.
A number of studies on diet show that it is related to many chronic degenerative diseases. However, most rely on diet questionnaires and are dependent on memory and honesty in answering. A new study from the Linus Pauling Institute took a different approach. They measured the plasma biomarkers for a variety of nutrients to see if they could correlate these nutrients in the blood with regard to cognitive function in aging subjects and MRI evaluations of brain shrinkage.
They took 30 plasma biomarkers measured in 104 subjects with a mean age of 87 years. Females made up 62 percent of the group. The nutrients evaluated included B-complex vitamins (B1, B2, B6, B12, and folate), and vitamins C, D, and E, as well as marine omega-3 fatty acids. They also evaluated trans fat levels. (Bowman GL, et al., Nutrient biomarker patterns, cognitive function, and MRI measures of brain aging. Neurology. 2011 Dec 28. [Epub ahead of print])
They measured brain volume (shrinkage is associated with declining cognitive abilities) using MRI testing and they did psychometric tests associated with thinking abilities. Two nutrient biomarker patterns were associated with higher brain function and less brain shrinkage. One was the pattern with high plasma vitamins, and one was high in marine omega-3 lipids. On the other hand, the nutrient pattern with high levels of trans fatty acids (found in margarines and commercial shortenings, common in highly processed foods) was associated with poorer cognitive function and more brain shrinkage.
The pattern with high vitamins had a broader beneficial effect than the pattern with high omega-3 lipids, but both were helpful. These nutrients are those found in a diet with a wide variety of vegetables, fruits, nuts, seeds, whole grains, beans, and certain fish. These are also the nutrients that many people take as supplements, so it is not clear that the entire beneficial effects were due to diet alone.
Vitamin D has been frequently in the news lately because of research showing its numerous and varied health benefits that go beyond its help in maintaining bone density. However, a new study suggests that it is not as helpful as the other studies have concluded from their data. This intervention study with vitamin D and calcium found no benefit in terms of vascular mortality or cancer.
Participants included 5292 people (mostly women) who took calcium (1000 mg), vitamin D3 (800 IU), both, or a placebo. They were treated for 2 to 5 years with a follow-up three years afterwards. They evaluated whether the supplements affected overall mortality and death from vascular disease, as well as cancer incidence and cancer mortality. (Avenell A, et al., Long-Term Follow-Up for Mortality and Cancer in a Randomized Placebo-Controlled Trial of Vitamin D3 and/or Calcium (RECORD Trial). J Clin Endocrinol Metab. 2011 Nov 23. [Epub ahead of print])
The more serious problem is they had no way to know if the supplements were sufficient to raise blood levels to the range that is protective. The dose of 800 IU of vitamin D is usually inadequate for treatment of low vitamin D levels, and daily doses of 4000 to 10,000 IU are given commonly with testing to see vitamin D blood levels. Earlier studies that showed protection indicated that the higher blood levels are necessary for full benefits.
In this study, the intervention had no statistically significant influence on mortality or cancer incidence. The researchers acknowledged some problems. One was that the subjects were not fully compliant with taking their supplements, and that evaluating them later it was found that those who were more compliant had a trend toward lower mortality (although still not statistically significant).
Exercise, including walking, has numerous beneficial effects, but how much is needed to get the benefits? In a study of 57 post-menopausal women researchers attempted to answer this question. The subjects were 50 to 70 years old and they were evaluated for body composition, energetic metabolism, and functional capacity in relation to the number of steps they took in a day. (Barbat-Artigas S, et al., Is functional capacity related to the daily amount of steps in postmenopausal women? Menopause. 2011 Dec 8. [Epub ahead of print])
They were divided into three groups: sedentary (less than 7500 steps per day), moderately active (7500-10,000 steps per day), and active (greater than 10,000 steps). A daily amount of 10,000 steps was associated with lower body weight, less fat mass, better endurance, and higher maximal oxygen consumption. However, while this level of exercise (walking only) was not associated with an increase in muscle mass or muscle functions the benefits indicated lower cardiovascular risks.
This lack of some benefits might have been related to inadequate exercise levels, or possibly to having too few participants to reveal significant results. In addition to regular walking or jogging, it appears beneficial to add resistance training (with weights or elastic bands, for examples) to build muscle mass and strength.
In a large study in the U.S., 492,186 participants completed detailed diet assessments to evaluate their intake of chemicals found in cooked and processed meats. These chemicals included heme iron, heterocyclic amines (HCA), polycyclic aromatic hydrocarbons (PAH), nitrate, and nitrite. They were followed for an average of nine years.
Those with the highest level of meat intake had a 20 to 30 percent increase in the risk of some forms of kidney cancer, and double the risk of some other forms of kidney cancer. (Daniel CR, et al., Large prospective investigation of meat intake, related mutagens, and risk of renal cell carcinoma. Am J Clin Nutr. 2012 Jan;95(1):155-62. Epub 2011 Dec 14.) Red meat and processed meats have been associated with increased risks of other forms of cancer as well.
Part of the problem is the chemicals that are found in processed meats, and part is due to the chemicals formed when meat is cooked. Heme iron is the form found in blood as part of hemoglobin. While iron is an important nutrient, an overabundance of it can lead to health problems related to free radical formation.
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