Some Sample Correlations

We all know that correlation is not causation. Causation arrows are not always clear, and sometimes two factors that correlate to each other are actually caused by a third factor.

My favorite example of correlation not proving causation is that it is not appropriate to say that firemen cause fires because every time there's a fire there are firemen there.

Correlation is expressed as a decimal between -1 and 1.
1 is a perfect positive correlation. An increase in one variable yields a proportionate increase in another one.
-1 is a perfect negative correlation. An increase in one variable yields a proportionate decrease in another one.
0 is no correlation. A change in one variable has no relation to changes in another one.

Tom Naughton, who made the movie Fat Head writes a blog. A recent one discussed a large study called the NIH-AARP Diet and Health Study. A number of correlations between diet and health outcomes were observed with varying levels of correlation. He discusses the significance of the study and correlations and there are some really good comments after the post.

He talks about some of the correlations found in the study, and I realized that I didn't have a really good sense of what these correlations look like, so I generated some.

Here are the correlations assuming underlying uniform distributions between two variables. Note that even a 0.6 correlation has a lot of variability.

Here are the correlations assuming underlying normal distributions between the two variables. These points are more centrally grouped because of the nature of the underlying distributions.





A fun allegory on correlation and causation

Correlation is not causation

Mindful vs. Mindless Eating

This post will catch me up on my one per month promise. You may have noticed that the post I did last month didn't count because it was just a bunch of links.

Fitness Black Book blog did a nice post about mindless eating and some of the studies that have demonstrated how external cues indirectly cause people to eat more.

You may recall that I posted about mindful eating some time ago.

I will reiterate part of what I said then:

"Fourth, eat only when you are hungry. People eat for reasons besides sustenance. Sometimes there is an emotional attachment to eating in which food is used to medicate one’s psyche. This is a type of addiction. Other times people eat because it just tastes sooooo good or they simply don’t want to waste food. If you find yourself using food for emotional support or overeating at special events, try to find a way to stop that."

I was traveling last week, visiting some friends. I found myself eating and drinking because it-was-time-to-eat-and-we-were-at-a-nice-restaurant-with-good-wine. I wasn't hungry. I ate and drank a lot anyway. I gained a nice layer of subcutaneous fat over muscles that had previously been visible. Not just from one meal, but from a whole week of similar temptations and behaviors.

This is especially a problem at restaurants. They give big portions because they can charge more for them. Then perhaps you eat all of it because it's a hassle to take it home or you don't want to bother. Buffet restaurants are impossible for many people. Holiday celebrations can also be a time of overeating. Don't succumb to the pressure to eat everything, but listen to your hunger and and take your time eating. Hunger is driven by a number of factors including empty stomach, and cells not receiving sufficient nutrients. You can get past the empty stomach part, but if your cells are not receiving enough fuel to do their jobs, it will eventually override your "willpower."

So in thinking about all this, I had a realization. Most people are in a pattern of eating at certain times in the day. We wake up and eat breakfast, then around noon have lunch, then finally at 7 in the evening we have dinner. It is important socially to have meals with other people and especially family. We get our three square meals on a set schedule. But in doing so, we lose the sense of our natural rhythms. We eat when we're not hungry, and we eat what is put in front of us. When that happens, we find ourselves complaining about problems with portion control.

What To Do Then

The solutions are obvious but there are two prerequisites: a body that is hormonally able to burn its own fat as fuel (low insulin environment) and mindfulness about eating when you do not feel hungry. Eat very lightly so you can fulfill the social needs without blowing your diet, or if you foresee a big meal coming up, skip the one before it or after it to compensate.

The other thing to think about is to consider your bad week as a break from your diet. This is actually a good thing as pointed out by Lyle McDonald.


Link to the book Mindless Eating by Brian Wansink

Dear E4E. A Letter to Myself

Dear E4E,

My 20 year old son who lives across the country with his mother, seems to want to have nothing to do with me. I have called him, texted him, and left messages on his facebook page. I get no response from him.


Recently, he left his job (released for being late). Now he contacts me and wants to visit. Yay.


Except, when I try to contact him to set dates, he doesn't respond. It's really odd. For the life of me, I can't think of anything I've done to anger him or drive him away. I feel hurt and sad about this.


What the heck is going on?


Signed, Baffled Engineer

Dear Baffled,


Regardless of whether you slighted him, the answer is the same--continue to reach out. Hold out a hand of unconditional, non-judging love.


Yes, you feel hurt and maybe want to punish. Perhaps you think it's terribly undignified or weak to reach out unrequitedly. Forget that.


But he gave you the cold shoulder and maybe you didn't deserve it. It doesn't matter. But you're a dude. You learned a long time ago not to take crap from anyone. To return disrespect with greater disrespect.


That's OK in battle, but this is not battle. It's not a power or blame game. This is family. Families are not a democracy, they're more like a benevolent dictatorship, or even communism (from each according to his abilities, to each according to his needs).


You are the parent; you are the adult. That is your role in this scenario. Unless a family member is actively hurting the family, your job is to strive to maintain cohesiveness.


Now try to look at it from your son's perspective. He's 20 years old, he was out earning lots of money and feeling pretty independent. He probably lost sight of the importance of family; maybe he didn't really understand the importance of maintaining contact. Perhaps you could have done a better job over the years of keeping touch with him. (Remember Cat's in the Cradle by Harry Chapin?)


Perhaps, he didn't think that he was meeting your expectations (good grades, go to college, etc.) and was feeling ashamed about that. Perhaps he had a secret that he thought would disappoint you in some way. Again, it really doesn't matter.


Remember, it's not your job to judge him or try to change him. Regardless of his emotional age or maturity, he is an adult now. Accept him as he is and do what you can to help him succeed in his life. Be proactive in keeping communications open. Hope that he will come around.


Good luck.
E4E

Diet and Health Some Media Links

There have been a number of good movies, books, and youtube clips lately that support some of the ideas around a more healthy way of eating and living.

I put some links below.

By the way, I'm not counting this post as one of my monthly posts. It's just too easy.

Paleo Eating


Paleo Exercise



Fathead: The Movie


Excellent introduction, with some humor, on many of the subjects that Taubes writes about in Good Calories, Bad Calories (link below).

Good Calories, Bad Calories
I am rereading sections of this book and after a year and a half of studying and reading about health, diet, and exercise, I find myself more impressed than ever at the quality of this book. It's not an easy read, but if it ever can break free from the being labeled in the category of diet books, could actually make a difference in the world.
Paperback


Hardcover




My Big Fat Diet
Described as "Supersize Me meets Northern Exposure in My Big, Fat Diet when the Namgis First Nation of Alert Bay gives up sugar and junk food, returning to a traditional style of eating for a year to fight obesity and diabetes."

I haven't seen it, but I have heard good things about it.

Is Vitamin D a Silver Bullet?

I am not a big believer in "silver bullets." But that belief system may be changing for me.

If you're not aware, much of the blogosphere, especially low-carb. primal, and/or paleo blogs have been abuzz about the importance of Vitamin D in preventing sickness and disease.

So, it turns out that Vitamin D is not technically a vitamin. It is a steroid hormone or prohormone. Your body is theoretically capable of creating all it needs in your skin from sunlight (specifically UVB rays), but in wintertime, far from the equator there is not enough sunlight. It is a likely driver of skin color--the reason that those who live near the equator have darker skin than those closer to the poles. It is why so many people get sick in the winter, yet are healthy all summer, and a likely reason that latitude is a good correlation with cancer incidence.

I have a multitude of links below, but I would like to share my experience from the past few months. I have been supplementing my vitamins with Costco Vitamin D3 tablets. Each tablet is 1000 i.u. These are dry tablets and I want to note that I have seen some recommendations to take oil-based gel caps for more reliable absorption.

In a typical winter, I get 2 - 4 colds, each one lasting a good week, requiring tons of Nyquil, Dayquil, Mucinex, etc to help get me through. Typically, I would feel some scratchiness in the back of my throat. That would progress to stuffy nose, and soon after down to my lungs.

This winter has been different though. I was typically taking about 4000 i.u. per day. When I felt the scratchy throat (two or three times this year), I'd double it for a few days. About a week ago, my daughter was visiting me on spring break. I was a little lax with my Vitamin D--probably missed a day or two. I felt the throat scratchiness and for some reason attributed it to allergies, so I didn't increase D.

The scratchy throat on Wednesday had progressed by Friday to bronchitis. I felt like death warmed over. My doctor told me that it would get worse before it got better. When I went home after the doctor, I took 10,000 i.u. of my Vitamin D as well as some mucinex, (which I had already been taking).

By the next day, I felt 100% better (I took another 6,000 i.u. of Vitamin D) and by Sunday morning I felt almost well.

I can't recall ever recovering from a cold this quickly. The usual caveats apply. I am an n of 1, and there may be a placebo effect, but I am amazed at how I have felt this winter.

A recent study states that the evidence for Vitamin D is strong enough that it should become a recommendation for cancer prevention and treatment. PubMed, sponsored by the United States National Institutes of Health has hundreds of papers linking latitude and cancer, latitude and flu, seasonality and disease. The thread running through it all is, the less sunlight, the more disease.

Melanoma rates are increasing despite record amounts of sunscreen being used. It turns out that sunscreens filter UVB rays well, but in the past have not done a good job of filtering UVA. UVB causes sunburn and is the driver of Vitamin D synthesis in the body. UVA rays are a big driver of melanoma (the most deadly skin cancer) and other skin disorders. Part of the increase in skin cancer may be due to the false security and comfort from sunscreen, leading people to be in the sun more. I believe that another part is likely due to the dampening effect on Vitamin D production. Could that be creating higher risks for other cancers as well?

It is apparently unusual to get a Vitamin D overdose from the sun. From the Wikipedia article on Vitamin D. "Exposure to sunlight for extended periods of time does not normally cause vitamin D toxicity. This is because within about 20 minutes of ultraviolet exposure in light skinned individuals (3–6 times longer for pigmented skin) the concentration of vitamin D precursors produced in the skin reach an equilibrium, and any further vitamin D that is produced is degraded. Maximum endogenous production with full body exposure to sunlight is 250 µg (10,000 IU) per day."

Here is an excellent article from 2000 from the Medical College of Wisconsin. Here is an older article (the recommendations do not align well with the explanatory text, but the explanatory text is good). Here is an MSNBC article warning that "sunscreen has not been conclusively shown to protect against melanoma..." Richard at FreeTheAnimal did this sunscreen post.

So here's the e4e recommendation.

1. Get your Vitamin D levels (25(OH) D, Serum 25 Hydroxyvitamin D) tested. If your doctor won't order the test, try Grassroots Health.  Edit: I did a future post on which vitamin D test to get.
2. If your levels are below 40-60 ng/ml, take a Vitamin D3 supplement. People with darker skin and those who do not spend much time outdoors are more likely to have low levels of Vitamin D.
3. If you don't get the test, but find yourself having lots of colds and upper respiratory tract issues, take a vitamin D3 supplement try 4,000 i.u. for a few months and see if your health improves. This is especially important in the winter months. There appears to be little danger of Vitamin D toxicity.
   
4. Do not fear the sun, but treat it with respect. Try not to burn, cover up, develop a tan when the sun is less intense during the day. Some unprotected sun is ok, but don't overdo it.

The Vitamin D Council

Is Vitamin D Deficiency during pregnancy is a cause of Autism

Dr. Michael Holick Presentation

Can Vitamin D Help Prevent Swine Flu?

Vitamin D Anecdotes

Vitamin D Toxicity Is Rare

Heartscan Blog Vitamin D Writing

How About Vitamin K2?

Cool story about Vitamin D and flu

Some conditions are worsened by more Vitamin D

Free The Animal blog's Supplements Links

Animal Pharm Blog Vitamin D posts

Pubmed. An incredible resource for research abstracts.

Heartscan Blog - Vitamin D for the pharmaceutically challenged

Whole Health Source - a good resource

Dr. Briffa has information about Vitamin D and heart disease

Live in the Now

It is good to have an end to journey toward; but it is the journey that matters, in the end." --Ernest Hemingway

I have been living in the now recently (mostly at work) and as such, have had little time to focus on e4e this month.

The good news is that my job has been a big focus. That's also the bad news.

So this will be simply a short reminder to know what you want as your destination in life or in your tasks, but to live in the present as well. Sometimes your focus is drawn very much to one narrow aspect of your life. You can do that for a short time, but it is not sustainable for most people. Your loved ones want you to be a part of their lives. Take time out from the workday world. Find the correct balance between urgent and important, long and short term, physical and mental/spiritual.

Finding that balance is life's journey.