Sunday, July 22, 2007

Milk gets some praise

Considering how fattening it is, praise for milk is a bit unexpected. The findings are however very weak -- a slight difference between extreme groups found only by aggregating a variety of not-very-comparable studies. Certainly no reason for anybody to increase their milk intake

Calcium and vitamin D, whether from food or supplements, may help lower the risk of developing type 2 diabetes, according to a research review. A number of studies have found links between type 2 diabetes risk and calcium, vitamin D and dairy food intake. When the results from these studies are combined, the new review found, people with the highest intakes of vitamin D and calcium had an 18 percent lower risk of diabetes than those with the lowest intakes. Similarly, people who ate the most dairy food had a 14 percent lower diabetes risk than those who ate the least dairy.

Though it's not clear why calcium and vitamin D are linked to diabetes risk, lab research has pointed to some possibilities, according to the review authors, led by Dr. Anastassios G. Pittas of Tufts-New England Medical Center in Boston. Both nutrients may be important in the functioning of insulin-producing cells in the pancreas, and in the body's proper use of insulin, the researchers explain in their report, published in the Journal of Clinical Endocrinology & Metabolism.

Insulin is a hormone that helps move sugar from the blood into the body's cells to be used for energy; type 2 diabetes develops when the body becomes resistant to insulin, allowing blood sugar levels to soar. Only a limited number of studies have tested whether calcium or vitamin D supplements can improve the body's insulin sensitivity and blood sugar metabolism. And the studies that have been done have reached conflicting conclusions, the review found.

A few trials have, however, suggested that the supplements may forestall type 2 diabetes in people who are on the verge of developing diabetes, or "pre-diabetic," based on their blood sugar levels, according to Pittas and his colleagues. It's too soon to recommend calcium or vitamin D for managing diabetes, the researchers conclude, but more clinical trials are warranted. Many Americans do not get enough vitamin D or calcium, they note, and supplementing people's diets with the nutrients would be an easy, inexpensive way to prevent or treat type 2 diabetes.


Journal Abstract follows:

The Role of Vitamin D and Calcium in Type 2 Diabetes. A Systematic Review and Meta-Analysis

By Anastassios G. Pittas et al.

Context: Altered vitamin D and calcium homeostasis may play a role in the development of type 2 diabetes mellitus (type 2 DM).

Evidence Acquisition and Analyses: MEDLINE review was conducted through January 2007 for observational studies and clinical trials in adults with outcomes related to glucose homeostasis. When data were available to combine, meta-analyses were performed, and summary odds ratios (OR) are presented.

Evidence Synthesis: Observational studies show a relatively consistent association between low vitamin D status, calcium or dairy intake, and prevalent type 2 DM or metabolic syndrome [OR (95% confidence interval): type 2 DM prevalence, 0.36 (0.16-0.80) among nonblacks for highest vs. lowest 25-hydroxyvitamin D; metabolic syndrome prevalence, 0.71 (0.57-0.89) for highest vs. lowest dairy intake]. There are also inverse associations with incident type 2 DM or metabolic syndrome [OR (95% confidence interval): type 2 DM incidence, 0.82 (0.72-0.93) for highest vs. lowest combined vitamin D and calcium intake; 0.86 (0.79-0.93) for highest vs. lowest dairy intake]. Evidence from trials with vitamin D and/or calcium supplementation suggests that combined vitamin D and calcium supplementation may have a role in the prevention of type 2 DM only in populations at high risk (i.e. glucose intolerance). The available evidence is limited because most observational studies are cross-sectional and did not adjust for important confounders, whereas intervention studies were short in duration, included few subjects, used a variety of formulations of vitamin D and calcium, or did post hoc analyses.

Conclusions: Vitamin D and calcium insufficiency may negatively influence glycemia, whereas combined supplementation with both nutrients may be beneficial in optimizing glucose metabolism.

The Journal of Clinical Endocrinology & Metabolism Vol. 92, No. 6 2017-2029

Gene may be a fountain of youth

One of the genes that protects people from cancer may also help delay ageing, according to a study published yesterday. The findings could lead to new drugs that prevent or fight cancer while extending healthy youth and lifespan, said Manuel Serrano, a researcher at the Spanish National Cancer Research Centre, who worked on the study.

Dr Serrano said researchers genetically changed mice to have an extra copy of a key cancer-fighting gene called p53 and found it also played an important role in delaying ageing. "Everyone agrees that the ageing is produced by the accumulation of faulty cells," Dr Serrano said. "In other words, p53 delays ageing for exactly the same reason that it prevents cancer." The study was published in the journal Nature.

Previous cancer studies have shown that p53 can cause premature ageing symptoms by killing too many cells when it goes into overdrive, but Dr Serrano said his research strictly regulated the gene so that it turned on only when needed. The gene -- and another that regulates signals to p53 -- did their normal job of producing a protein that kills damaged cancer cells. But the researchers found that mice with an extra copy of the genes actually lived longer even when stripping out the impact of having less cancer. "This is the first anti-cancer gene tested for its effect on ageing," Dr Serrano said. "The mice lived 16 per cent longer in their average lifespan."

The p53 gene makes sure that damaged cells destroy themselves and do not divide uncontrollably to cause a tumour. The role of p53 in cancer has been known for many years. Dr Serrano said he and his team applied this knowledge to ageing and targeting damaged cells. "The expectation is that having more p53, mice will have a stricter quality control for cells, hence less cancer and less ageing," he said.

Dr Serrano said other research had shown that mice and worms that ate less had slower metabolisms and lived longer. His study offers evidence that the mice can benefit from the extra copy of the genes without being starved.

The study opened up possibilities for drugs based on p53 to delay ageing, but researchers would need to find the right balance in boosting the gene to prevent potentially harmful effects, he said. "There are a number of chemical compounds that have been developed by the big pharmaceutical companies and these compounds are able to boost p53 in the organism," he said. "These compounds are being tested now for their possible anti-cancer activity and hopefully in the light of our study also for their possible anti-ageing activity."



Just some problems with the "Obesity" war:

1). It tries to impose behavior change on everybody -- when most of those targeted are not obese and hence have no reason to change their behaviour. It is a form of punishing the innocent and the guilty alike. (It is also typical of Leftist thinking: Scorning the individual and capable of dealing with large groups only).

2). The longevity research all leads to the conclusion that it is people of MIDDLING weight who live longest -- not slim people. So the "epidemic" of obesity is in fact largely an "epidemic" of living longer.

3). It is total calorie intake that makes you fat -- not where you get your calories. Policies that attack only the source of the calories (e.g. "junk food") without addressing total calorie intake are hence pissing into the wind. People involuntarily deprived of their preferred calorie intake from one source are highly likely to seek and find their calories elsewhere.

4). So-called junk food is perfectly nutritious. A big Mac meal comprises meat, bread, salad and potatoes -- which is a mainstream Western diet. If that is bad then we are all in big trouble.

5). Food warriors demonize salt and fat. But we need a daily salt intake to counter salt-loss through perspiration and the research shows that people on salt-restricted diets die SOONER. And Eskimos eat huge amounts of fat with no apparent ill-effects. And the average home-cooked roast dinner has LOTS of fat. Will we ban roast dinners?

6). The foods restricted are often no more calorific than those permitted -- such as milk and fruit-juice drinks.

7). Tendency to weight is mostly genetic and is therefore not readily susceptible to voluntary behaviour change.

8). And when are we going to ban cheese? Cheese is a concentrated calorie bomb and has lots of that wicked animal fat in it too. Wouldn't we all be better off without it? And what about butter and margarine? They are just about pure fat. Surely they should be treated as contraband in kids' lunchboxes! [/sarcasm].

Trans fats:

For one summary of the weak science behind the "trans-fat" hysteria, see here. Trans fats have only a temporary effect on blood chemistry and the evidence of lasting harm from them is dubious. By taking extreme groups in trans fats intake, some weak association with coronary heart disease has at times been shown in some sub-populations but extreme group studies are inherently at risk of confounding with other factors and are intrinsically of little interest to the average person.


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