the-psoriasis-treatment

In a previous post ( ) I used WarpPLS ( ) to analyze the model below, using data reported in a recent study looking at the relationship between red meat consumption and mortality. The model below shows the different paths through which smoking influences mortality, highlighted in red. The study was not about smoking, but data was collected on that variable; hence this post. When one builds a model like the one above, and tests it with empirical data, the person does something similar to what a physicist would do. The model is a graphical representation of a complex equation, which embodies the beliefs of the modeler. WarpPLS builds the complex equation automatically for the user, who would otherwise have to write it down using mathematical symbols. The results yielded by the complex equation, partly in the form of coefficients of association for direct relationships (the betas next to the arrows), have a meaning. Some may look odd, and require novel interpretations, much in the same...

The idea that pork consumption may cause cirrhosis has been around for a while. A fairly widely cited 1985 study by Nanji and French ( ) provides one of the strongest indictments of pork: “In countries with low alcohol consumption, no correlation was obtained between alcohol consumption and cirrhosis. However, a significant correlation was obtained between cirrhosis and pork.” Recently Paul Jaminet wrote a blog post on the possible link between pork consumption and cirrhosis ( ). Paul should be commended for bringing this topic to the fore, as the implications are far-reaching and very serious. One of the key studies mentioned in Paul’s post is a 2009 article by Bridges ( ), from which the graphs below were taken. The graphs above show a correlation between cirrhosis and alcohol consumption of 0.71, and a correlation between cirrhosis and pork consumption of 0.83. That is, the correlation between cirrhosis and pork consumption is the stronger of the two! Combining this with the Nanji a...

It is not very hard to find studies supporting one diet or another. Gardner and colleagues, for example, conducted a study in which the Atkins diet came out on top when compared with the Zone, Ornish, and LEARN diets ( ). In Dansinger and colleagues’ study ( ), on the other hand, following the Atkins diet led to relatively poor results compared with the Ornish, Weight Watchers, and Zone diets. Often the diets compared have different macronutrient ratios, which end up becoming the focus of the comparison. Many consider Sacks and colleagues’ conclusion, based on yet another diet comparison study ( ), to be the most consistent with the body of evidence as a whole: “Reduced-calorie diets result in clinically meaningful weight loss regardless of which macronutrients they emphasize”. I think there is a different conclusion that is even more consistent with the body of evidence out there. This conclusion is highlighted by the findings of almost all diet studies where participants were followe...

In this previous post I analyzed some data from the China Study that included counties where there were cases of schistosomiasis infection. Following one of Denise Minger ’s suggestions, I removed all those counties from the data. I was left with 29 counties, a much smaller sample size. I then ran a multivariate analysis using WarpPLS ( warppls.com ), like in the previous post, but this time I used an algorithm that identifies nonlinear relationships between variables. Below is the model with the results. (Click on it to enlarge. Use the "CRTL" and "+" keys to zoom in, and CRTL" and "-" to zoom out.) As in the previous post, the arrows explore associations between variables. The variables are shown within ovals. The meaning of each variable is the following: aprotein = animal protein consumption; pprotein = plant protein consumption; cholest = total cholesterol; crcancer = colorectal cancer. What is total cholesterol doing at the right part of the gr...

In the comments section of Denise Minger’s post on July 16, 2010 , which discusses some of the data from the China Study (as a follow up to a previous post on the same topic), Denise herself posted the data she used in her analysis. This data is from the China Study. So I decided to take a look at that data and do a couple of multivariate analyzes with it using WarpPLS ( warppls.com ). First I built a model that explores relationships with the goal of testing the assumption that the consumption of animal protein causes colorectal cancer, via an intermediate effect on total cholesterol. I built the model with various hypothesized associations to explore several relationships simultaneously, including some commonsense ones. Including commonsense relationships is usually a good idea in exploratory multivariate analyses. The model is shown on the graph below, with the results. (Click on it to enlarge. Use the "CRTL" and "+" keys to zoom in, and CRTL" and "-...

Ancel Keys is often heavily criticized for allegedly originating the fat phobia that we see today in the US and other countries, perhaps with good reason. But he has also made many important contributions to the health sciences. One of them was the index known as body mass index (BMI), calculated based on a person's weight and height. Unlike other measures, such as body fat percentage and body fat mass, BMI is very easy to calculate; divide your weight (kg) by your height (m) squared. BMI is strongly correlated with body fat percentage, and body fat mass. Very muscular people are exceptions; they may have a high BMI and yet reduced body fat. Excessive body fat mass leads to chronic inflammation, due in part to elevated circulating levels of pro-inflammatory hormones such as tumor necrosis factor-alpha (cute name eh?). Chronic inflammation, in turn, leads to increased incidence of cancer. Thus it should be no surprise that having a BMI above 30 (obesity level) is strongly correlated...

Humans, like many animals, evolved to be episodic eaters and spend most of their time fasting. Body fat is the main store of energy in the human body. Excess dietary carbohydrates and fat are stored as body fat, in specialized cells known as adipocytes. Excess dietary protein is not normally stored as body fat . Adipocytes can be seen as being part of a very important and distributed endocrine organ, being responsible for the release of many different hormones into the bloodstream. One of these hormones is adiponectin. Other important hormones secreted by body fat tissue are leptin and tumor necrosis factor-alpha. Among hormones, adiponectin is particularly interesting because it is negatively correlated with body fat mass. That is, unlike other hormones such as leptin and tumor necrosis factor-alpha, a decrease in body fat mass (a well known health marker) is associated with an increase in adiponectin. This has led some researchers to speculate that adiponectin is a causative factor t...

George Hamilton admits that he has been addicted to sunbathing for much of his life. The photo below (from: phoenix.fanster.com), shows him at the age of about 70. In spite of possibly too much sun exposure, he looks young for his age, in remarkably good health, and free from skin cancer. How come? Maybe his secret is vitamin D. Vitamin D is a fat-soluble pro-hormone; not actually a vitamin, technically speaking. That is, it is a substance that is a precursor to hormones, which are known as calcipherol hormones (calcidiol and calcitriols). The hormones synthesized by the human body from vitamin D have a number of functions. One of these functions is the regulation of calcium in the bloodstream via the parathyroid glands. The biological design of humans suggests that we are meant to obtain most of our vitamin D from sunlight exposure. Vitamin D is produced from cholesterol as the skin is exposed to sunlight. This is one of the many reasons (see here  for more) why cholesterol is ver...

Some types of cancer have traditionally been higher among the Inuit than in other populations, at least according to data from the 1950s, when a certain degree of westernization had already occurred. The incidence of the following types of cancer among the Inuit has been particularly high: nasopharynx, salivary gland, and oesophageal. The high incidence of these “traditional” types of cancer among the Inuit is hypothesized to have a strong genetic basis. Nevertheless some also believe these cancers to be associated with practices that were arguably not common among the ancestral Inuit, such as preservation of fish and meat with salt. Genetic markers in the present Inuit population show a shared Asian heritage, which is consistent with the higher incidence of similar types of cancer among Asians, particularly those consuming large amounts of salt-preserved foods. (The Inuit are believed to originate from East Asia, having crossed the Bering Strait about 5,000 years ago.) The incidence o...