29 April 2011

Calcium: U.S. adults still not getting enough

A new study suggests most U.S. adults continue to fail to get enough of the mineral through diet and supplementation to meet recommended levels.

University of Connecticut and Yale University researchers examined data from National Health and Nutrition Examination Survey collected from 9,475 adults between 2003 and 2006. They found that, although dietary calcium intake was reported highest in older age groups, the amounts remained insufficient to meet adequate intake standards for age groups 50 years and older.

These inadequate intakes come despite the fact that more than half of individuals ages 19 and older were taking a calcium supplement, according to the authors. For men, supplementation increased from 34 percent in the 19 – 30 age group to 54 percent in the 81 and older age group. The percentage of women taking supplements rose from 42 percent to 64 percent across the same range of age groups.

"Adequate lifelong calcium intake is essential to optimizing bone health," remind the study authors, who published their findings in the May 2011 issue of Journal of American Dietetic Association. They also recommend "new approaches to increasing the frequency and level of calcium supplement use to enhance calcium density in diets."

Calcium is the most abundant mineral in the body, primarily found in the bones and teeth. As bones develop, calcium, along with other minerals, crystallizes on the collagen matrix of the bone, making it denser and giving it strength and rigidity. The body loses calcium continuously, and if this loss is not replaced through diet, the body will remove calcium from the bones to perform necessary functions such as regulation of muscle contraction. This removal causes bones to become soft and brittle, making them prone to fractures.

Adequate calcium intake is necessary for strong and healthy bones. The current recommended intake of calcium is between 1,000 mg and 1,300 mg per day. Good sources (more than 300 mg per serving) of calcium include dairy products such as low-fat milk, cheese, and yogurt. Dark green vegetables such as broccoli, kale, and spinach can also add about 90 milligrams of this mineral to daily intake. In addition, calcium-fortified foods (orange juice and breakfast cereals) and dietary supplements can also help fill gaps.
Other important factors in optimizing bone health include engaging in weight-bearing exercise and obtaining recommended amounts of vitamins D and K2 daily.

Reference: Mangano KM, Walsh SJ, Insogna KL, Kenny AM, Kerstetter JE. Calcium Intake in the United States from Dietary and Supplemental Sources across Adult Age Groups: New Estimates from the National Health and Nutrition Examination Survey 2003-2006. J Am Diet Assoc 2011;111:687-95.


Time and time again, studies have shown that calcium when combined with vitamin D are effective in increasing bone density. However, there's been a lot of back and forth in the calcium world around the topic of supplements, particularly their efficacy and safety. A critical piece lacking in the conversation is of absorption since calcium is one mineral that depends on a few factors -- vitamin D, doses that oversaturate absorption, too much absorbed at once.

The best approach for obtaining calcium is perhaps to consume it as we would have back in the time of our hunter-gatherers ancestors before the agricultural revolution and pastoralism, which is by getting a little here and a little there when we only obtained it from the leaves of plants. That's not to say that we should only get it from plant leaves, but that we should get it in smaller amounts in sustained fashion over the course of a day.

27 April 2011

Wake up, Neo-evolution

What would you change about your own naturally evolved, naturally flawed body? Would you choose genetics to avoid diseases like Alzheimer's, diabetes, and cancer? Would you enhance your brain to increase memory and to boost creativity? Would you choose more fast-twitch muscle fibers to run faster or longer? Would you live longer?

These are the questions that Harvey Fineberg, president of the Institute of Medicine, discusses in this new TED talk given in March that was posted only this month. Fineberg says that a new era of neo-evolution -- in which we, as humans, could guide the selection of traits that would define the course of humanity -- is upon us, and he called it "exciting," but "frightening."

I want to answer all of his questions with a "Yes, sign me up!" Who is insane enough to reject a world with an absence of disease, of aging, of dying and death?

Apparently, there are quite a few people. Hava Tirosh-Samuelson, professor of history at Arizona State University, is one of them. Earlier this month, at ASU's Origins Project Science and Culture Festival Tirosh-Samuelson was speaking about a completely different topic when she suddenly surprised us with a few critical words of the "so-called trans-humanist movement."

In a nutshell, her argument is that we still haven't a clue of what humanity is to begin with, so reason suggests against trying to define what it should be in the future. Naturally, after her talk, I decided to ask Tirosh-Samuelson a few questions about her views.

22 April 2011

Health at Telomere's Length

A health checkup could soon incorporate a telomere measurement to estimate a person's biological age as a superior indicator of age-related degeneration and vulnerability to disease than chronological age, reports Mitch Leslie in an article entitled, "Are Telomere Tests Ready for Prime Time," published in Science magazine today.

The article reports that two companies have announced plans to start performing tests for the general public this year: Life Length of Madrid has already began offering the tests to patients and Telome Health, of Menlo Park, Calif., will begin to make them available to clinicians sometime later this year.

Already, medical researchers have employed telomere measurement for predicting illness and tailoring treatments to save lives, yet the article reports that skepticism exists about how effective telomere tests will be in predicting disease or determining lifespan in a clinical setting.

"By curtailing self-renewal, worn-down telomeres might promote the senescence of our bodies—although how much has been controversial," writes Leslie.

On one side of the issue is Telome Health co-founder Elizabeth H. Blackburn, a cell biologist at University of California, San Francisco (UCSF), who is quoted as saying "Telomeres are an integrative indicator of health."

Carol W. Greider, a former graduate student in Blackburn's lab and a molecular biologist at Johns Hopkins University School of Medicine in Baltimore, Maryland, disagrees saying, “Do I think it’s useful to have a bunch of companies offering to measure telomere length so people can find out how old they are? No.”

In 2009, Blackburn and Greider were awarded the Nobel Prize in Physiology or Medicine, along with Jack W. Szostack, for the discovery of how chromosomes are protected by telomeres and the enzyme telomerase.

Telomeres are comprised of non-coding, repetitive sequences of coiled DNA that serve as protective caps at the end of chromosomes, preserving their integrity and keeping them from fraying and sticking to each other.

Shortened telomeres are linked with a greater chance of developing cardiovascular disease, diabetes, Alzheimer's disease, and other chronic diseases. In the last few years, studies have also showed that the rate of telomere shortening can be strongly affected by diet and lifestyle.

According to the article, among factors that affect telomeres harshly are smoking, drinking heavily, obesity, and chronic psychological stress. On the other hand, meditation, exercise, a healthy diet, and higher blood levels in omega-3 fatty acids offer a buffer to help maintain longer telomeres.

The enzyme telomerase, which plays a role in helping to maintain telomere length, is a recognized target of pharmaceutical-nutraceutical companies for producing possible therapies in the future.

14 April 2011

Stress Awareness Month and the baboon inside you

I love to read about Robert Sapolsky's baboons. They give me a kind of peace -- the kind received when you succeed in letting go of a stressful situation by thinking, "we're all just a bunch of baboons."

What you get from Sapolsky's books, apart from its enjoyable wittiness, is a unique snapshot on how baboons are affected by stress, which is more or less the same way that we are affected by stress. Only, while baboons are stressed occasionally -- by a more dominant baboon or to escape a predator, for example -- we humans have built ourselves an environment where we're stressed chronically.

What African Americans should know about vitamin D and heart health

A while back, I was talking with a friend of mine. He was a giant of a black man and we spoke about his  blood pressure woes and his weight issues. So I asked him about his diet, his habits, and all that. He told me all about it: How he ate all the right foods, how he was trying to avoid the wrong ones, and how he recently started walking on his treadmill.

I said to him, "What do you do all day?"

He said, "I'm in the office all day."

"What do you do at lunchtime?"

"I usually have a protein shake or eat a salad with some chicken."

That's good, I tell him. But I want you to do one more thing. It's easy. While or after you eat, take a walk. Outside. In the parking lot. Once or twice a week.

OK, he says. "But why outside?"

I said, "Sunlight and vitamin D." Then, I told him a story we should all be familiar with by now, which went something like this:

Darker skin is a result of greater production of a pigment called melanin that rewards skin with a natural protection against ultraviolet light. Ultraviolet light would otherwise burn skin, destroy the body's stores of nutrients like folic acid that are needed for refurbishing DNA, increase risk of neural tube defects among other reproductive problems, and also raise risk of skin cancer.

So, in short, melanin is a good thing. Near the equator, with strong UVB rays aplenty to compensate slower vitamin D production, darker skin offers an evolutionary advantage that would only serve to sustain naked humans. But, as often is the case, reward comes with recompense. The downside of higher amounts of melanin is that the pigment interferes with the skin's ability to absorb enough UVB rays to activate Vitamin D's pre-cursor into a full-fledged hormone.
As is well-documented, humans at higher latitudes with dark skin would never have survived over the generations without shedding the extra melanin and opting for a lighter color. Lighter color would afford more UVB absorbed, more D created, stronger bones and, as evidence emerges to show, better cardiovascular health. During summer months, lighter-skinned humans who had migrated to higher latitudes collected vitamin D in fat as they gained weight, then released it into the bloodstream when they shed weight during sunlight-lacking winter months.

On the other hand, when darker-skinned humans live in a Northern latitudes of the United States -- as African Americans do -- you can bet that problems will arise.

Then, I gave him some details about asking his doctor for a 25-hydroxyvitamin D test.

A couple of weeks later, I spotted him outside walking around a parking lot. He tells me, "Thanks so much, David. I had no idea about vitamin D. Plus, my doctor says the walking and the vitamin D are helping my heart."

While attending Experimental Biology (#eb2011) over the weekend, one of the presentations had me thinking about my friend. And that was Richard Harris, Ph.D., of Georgia Health Sciences University in Augusta, presenting a study on vitamin D supplementation in African Americans.

What Dr. Harris and his fellow Georgia researchers found was that vitamin D supplementation in overweight African American adults in a single dose of 60,000 IU every for four weeks every 16 weeks improved blood vessel endothelial function – the equivalent of 2,000 IU since vitamin D has a half life of about three weeks.

It was notable that they used overweight adults, since extra weight can increase blood volume, raise blood pressure, resulting in rigid, inflamed vessels. Details are that the researchers used an inflatable cuff to increase blood flow in the brachial arteries of each of the participants, then an ultrasound to measure flow-mediated dilation.

What exactly vitamin D was able to do is what Dr. Harris calls the "million-dollar question," according to this press release. But it's likely that the hormone acted directly on endothelial cells, on a receptor perhaps, that helps dilate blood vessels when needed. The more dilation, the easier it is for blood to flow through vessels.

This study is great news, especially for this population at higher risk for cardiovascular disease factors like higher blood pressure. However, there is still too little vitamin D deficiency awareness.

Here's what I say, Why not teach African Americans why they have a greater need for vitamin D from an evolutionary perspective?

In the case of my friend, it really helped put things in perspective. There's an easy solution for this mess, which is to take a walk around the block for a few minutes when UVB rays are out (mostly just in summer months) or, simply, by just taking a vitamin D supplement as they did in the summer. Lots of benefits to come from such an easy habit of getting D daily like better blood pressure along with better bone health.

Another thing is that the Institute of Medicine's recommended daily intakes of vitamin D (although they are based as if there were no sun-produced D at all) just make little sense when they don't treat all adults the same, not bringing high-risk groups into consideration. Until more research is available and the IOM can build on current guidelines by raising them for high-risk groups, African Americans should take health into their own hands by getting tested to make sure they keep 25-hydroxyvitamin D in healthy ranges continually.