Are Vitamin D Supplements Effective in Preventing Disease?

Are you one of the millions of people who are taking vitamin D supplements? People take vitamin D supplements to prevent depression, muscle weakness, cancer, heart disease, and who knows what else. And yet, there is a lack of evidence that vitamin D supplements will prevent any of these conditions.

The trend to test for and treat alleged vitamin D deficiencies took off in 2011 with the publication of a book entitled The Vitamin D Solution - A 3-Step Strategy to Cure Our Most Common Health Problems. The suggestion by the book's author that vitamin D levels of 21-29 ng/ml are insufficient for good health were a bit of a shocker, since blood levels of vitamin D of greater than 20 ng/ml are considered normal.  The book and several studies that seemed to support its thesis led to an increase in vitamin D screening blood tests, and to recommendations by many physicians that their patients consider taking vitamin D supplements.

However, the Institute of Medicine says that there is no evidence that people who have vitamin D levels above 20 ng/ml (i.e. normal vitamin D levels) will benefit from taking additional vitamin D.  In addition, two studies published this year show that vitamin D supplements don't prevent heart attacks and don't protect women against cancer. An ambitious 5-year study is now underway to try to determine once and for all whether vitamin D supplements are of any use in preventing cancer, heart disease, and stroke.

I don't know about you, but I'm taking vitamin D deficiency off my list of things to worry about, at least for now.

'Subclinical' Hypothyroidism is Being Over-treated

What was the most prescribed drug in 2016?   If you guessed a blood pressure medication, a cholesterol-lowering drug, insulin for diabetes, or even a painkiller such as oxycodone, you'd have been wrong.  It was levothyroxine, a drug used to treat hypothyroidism. But not all physicians are using this drug correctly; many are using it to treat 'subclinical' hypothyroidism.

Subclinical hypothyroidism is generally defined as a slightly elevated TSH (thyroid-stimulating hormone; indicating perhaps an under-responsive thyroid gland), accompanied by a number of vague and highly subjective symptoms such as tiredness, lack of motivation, and muscle aches and pains. It's called 'subclinical' hypothyroidism because levels of the two thyroid hormones, T3 and T4, are still normal, as opposed to true hypothyroidism in which there is a clear deficiency in these two hormones.

The problem is that many of the physical symptoms of hypothyroidism, such as tiredness and muscle aches and pains, are common complaints in older people.  So if their TSH levels are just a little over the normal level (which also often happens with age), physicians are increasingly putting their older patients on levothyroxine, regardless of what their T3 and T4 levels are.  As a result, fully 15% of older Americans are taking levothyroxine to treat their alleged symptoms.

However, recent evidence shows that other than lowering TSH levels to normal, levothyroxine doesn't have any effect on the actual "symptoms" patients are complaining about - no effect at all.  If this new evidence is correct, physicians could stop prescribing levothyroxine to treat 'subclinical' hypothyroidism entirely.  The proper use of levothyroxine is to treat patients with true hypothyroidism, in which T3 and T4 are demonstrably low.

Lyme Disease is On the Rise

People who live in the Northeast are aware of Lyme disease; a baffling, debilitating, bacterial infection spread by bites from certain types of ticks.  Lyme disease is difficult to treat if not detected and treated early.  The forecast is for an increase in the number of cases of Lyme disease this summer. The reason is an increase in the population of field mice last year; mice, it turns out, are a preferred host of the ticks that spread the disease.

Cases of Lyme disease in the U.S. have tripled in the past 20 years, according to the Centers for Disease Control and Prevention (CDC).  For more on why that is, see the recent article in The New York Times.

How can you prevent becoming infected? Your best defense is to avoid being bitten by ticks.  If you are outside in a tick-infested area, be sure to check yourself carefully for ticks after coming back inside.  Most ticks won't actually bite you in the first 12-24 hours or so, so it pays to get them off of you as soon as possible.

Updated Prostate Cancer Screening Guidelines

Just five years ago the U.S. Preventive Services Task Force (USPSTF) recommended that men 55-69 should be "discouraged" from having the PSA test to screen for prostate cancer (see this blog, May 27, 2012). At the time, the best evidence was that the risks of having a PSA test slightly outweighed the rewards. That's because the PSA test is not 100% accurate; sometimes it gives false positive results, meaning that the test indicates that prostate cancer might be present when in fact it isn't. According to the USPSTF, these false positive PSA tests were leading to biopsies (the next step in making a diagnosis), radiation, and sometimes even to surgeries for prostate removal, all of which carry some risk.

But just recently the USPSTF reversed course; now it recommends that men aged 55-69 should "have a conversation with their doctor" about the advisability of having the PSA blood test to screen for prostate cancer. Why the apparent about-face? Again, it's based on the best available evidence. The PSA test hasn't gotten any more reliable, but what has changed is what happens after a positive test result. Recent research has showed early, aggressive treatment after a positive PSA test isn't necessary and doesn't increase patient survival. That means that doctors can afford to wait, doing repeated PSA tests for years if necessary before recommending biopsies or treatment. As a result, the risks of having the PSA test (and everything that comes after) have declined to the point that the rewards now slightly outweigh the risks.

As before, the PSA test is not recommended for men over 70 (they're likely to die of something else before they would die of a slow-growing prostate cancer) or for men under 50 (prostate cancer is too rare in younger men for the test to be of much benefit).

Home Genetic Testing and Risk Assessment Approved by the FDA

Back in 2013, a company called 23andMe (referring to the 23 pairs of human chromosomes) offered a genome testing service that promised to analyze a sample of the DNA in your saliva for over 300 alleles, many of which were associated with increased risks of genetic diseases. At the time, the FDA claimed that providing information about future risk of genetic disease was tantamount to offering medical device, and ordered the company to stop selling the kits for medical purposes (see this blog, Dec. 5, 2013).

For a time thereafter, 23andMe survived by selling its kits for "entertainment", i.e. to provide insight into ancestry for those who were interested. But it kept working on the medical angle. In 2015 the company went back to the FDA and was given approval to provide genetic information regarding allele "carrier" status for 36 genetic conditions, such as cystic fibrosis and sickle cell anemia, as long as the company didn't make any statements about the risks of developing a genetic condition as a result of the alleles (see this blog Nov. 3, 2015).

Still, the company kept working on the goal of being able to provide customers with valid risk assessment data. And apparently they did a pretty good job, for this week the FDA gave 23andMe permission to identify 10 telltale markers of genetic diseases, including Parkinson's disease and late-onset Alzheimer's disease, and provide information about the likelihood that the customer will develop the genetic conditions associated with these markers (my emphasis added). It's a big win for a small company, and a testament to the company's perseverance.

A word of caution, however, before you decide to have your DNA analyzed. You should know that you may not be able to keep the results of your home genetic test private under certain circumstances (see this blog, Mar. 13, 2017).

A Texting-While-Driving Accident Claims 13 Lives

Here we go again. A lot has been written about the dangers of texting while driving, yet many of us just can't seem to resist the temptation. The death toll continues to climb.

Consider the most recent incident. Local sheriff's offices received several calls that a pickup truck was driving erratically on a two-lane highway west of San Antonio, Texas. One of the callers even recorded video footage of the truck. Although police responded to the calls quickly, they reached the pickup only after it had plowed head-on into a church van, killing 13 people. According to a Fox News report, the 20-year-old driver of the pickup truck (who survived the crash) said "I'm sorry, I'm sorry, I was texting."

Thirteen deaths is a lot to feel sorry for, especially when they could have been avoided so easily. And a lifetime of remorse is only part of what this young man will have to endure; what's the law going to do to him? I do truly feel sorry for him, because I'm sure he had no intention of harming anyone.

What's it going to take to get you to put down your phone while driving?