Vitamin D Supplements for Increasing Aging Muscle Strength

We have known for more than 400 years that muscle weakness is a common presenting symptom of vitamin D deficiency. Bones aren’t the only organs that respond to vitamin D—muscles do, too. However, as we age, our muscles lose vitamin D receptors, perhaps helping to explain the loss in muscle strength as we age. Indeed, vitamin D status does appear to predict the decline in physical performance as we get older, with lower vitamin D levels linked to poorer performance. As I discuss in my video in my video Should Vitamin D Supplements Be Taken to Prevent Falls in the Elderly?, maybe the low vitamin D doesn’t lead to weakness. Rather, maybe the weakness leads to low vitamin D. Vitamin D is the sunshine vitamin, so being too weak to run around outside could explain the correlation with lower levels. To see if it’s cause and effect, you have to put it to the test.

As you can see at 1:01 in my video, about a dozen randomized controlled trials have tested vitamin D supplements versus sugar pills. After putting them all together, we can see that older men and women taking vitamin D get significant protection from falls, especially among those who had started out with relatively low levels. This has led the conservative U.S. Preventive Services Task Force, the official prevention guideline setting body, and the American Geriatric Society to “recommend vitamin D supplementation for persons who are at high risk of falls.”

We’re not quite sure of the mechanism, though. Randomized controlled trials have found that vitamin D boosts global muscle strength, particularly in the quads, which are important for fall prevention, though vitamin D supplements have also been shown to improve balance. So, it may also be a neurological effect or even a cognitive effect. We’ve known for about 20 years that older men and women who stop walking when a conversation starts are at particularly high risk of falling. Over a six-month timeframe, few who could walk and talk at the same time would go on to fall, but 80 percent of those who stopped walking when a conversation was initiated ended up falling, as you can see at 2:14 in my video.

Other high-risk groups who should supplement with vitamin D include those who have already fallen once, are unsteady, or are on a variety of heart, brain, and blood pressure drugs that can increase fall risk. There’s also a test called “Get-Up-and-Go,” which anyone can do at home. Time how long it takes you “to get up from an armchair, walk 10 feet, turn around, walk back, and sit down.” If it takes you longer than ten seconds, you may be at high risk.

So, how much vitamin D should you take? As you can see at 3:00 in my video, it seems we should take at least 700 to 1,000 units a day. The American Geriatric Society (AGS) recommends a total of 4,000 IU a day, though, based on the rationale that this should get about 90 percent of people up to the target vitamin D blood level of 75 nanomoles per liter. Although 1,000 IU should be enough for the majority of people, 51 percent, the AGS recommends 4,000 IU to capture 92 percent of the population. That way, you don’t have to routinely test levels, since 4,000 IU will get most people up to the target level and “is considerably below the proposed upper tolerable intake of 10,000 IU/d.” The AGS does not recommend periodic mega-doses.

Despite the AGS’s recommendation, because it’s hard to get patients to comply with pills, why not just give people one megadose, like 500,000 units, once a year, perhaps when they come in for their flu shot? That way, every year, you can at least guarantee an annual spike in vitamin D levels that lasts a few months, as you can see at 4:00 in my video. It’s unnatural but certainly convenient, for the doctor at least. The problem is that it actually increases fall risk, a 30 percent increase in falls in those first three months of the spike. Similar results were found in other mega-dose trials. It may be a matter of too much of a good thing. See, “vitamin D may improve physical performance, reduce chronic pain, and improve mood” so much that people start moving around more and, thereby, increase fall risk. When you give people a whopping dose of vitamin D, they get a burst in physical, mental, and social functioning, and it may take time for their motor control to catch up to their improved muscle function. It would be like giving someone a sports car when they’ve been used to driving a beater. You’ve got to take it slow.

It’s possible, too, that such unnaturally high doses may actually damage the muscles. The evidence the researchers cite in support is a meat industry study showing you can improve the tenderness of steaks by feeding cattle a few million units of vitamin D. The concern is that such high doses may be over-tenderizing our own muscles, as well. Higher vitamin D levels are associated with a progressive drop in fracture risk, but too much vitamin D may be harmful, as you can see at 5:29 in my video.

The bottom line is that vitamin D supplementation appears to help, but the strongest and most consistent evidence for prevention of serious falls is exercise. If you compare the two, taking vitamin D may lower your fall risk compared to placebo, but strength and balance training with or without vitamin D may be even more powerful, as you can see at 5:41 in my video.


Other studies in which vitamin D supplements have been put to the test in randomized placebo-controlled studies, effectively proving—or disproving—their efficacy, are featured in videos such as:

That brings up a number of important questions, which I answer in these videos:

Unfortunately, most supplements are useless—or worse. Here are some additional videos on supplements I’ve produced that may be of interest to you:

For more on the benefits of exercise, see Longer Life Within Walking Distance and How Much Should You Exercise?

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations:

My new book, How to Survive a Pandemic, is out now!

How to Survive a Pandemic is now out! Note: if you checked on Amazon and noticed the Kindle and paperback versions were not available before, they are now! Join my email list to receive the preface of the book for free. 

I have a feeling many think How Not to Die is my first book, but it’s actually my 4th. Before I started NutritionFacts.org and switched to working on chronic disease, I had a career as Public Health Director at HSUS in Washington, DC specializing in emerging infectious disease. It was in that role that I was invited to defend Oprah, appeared on the Colbert Report, lectured at NIH and the Conference on World Affairs, and got to testify before Congress.

With my How Not to Diet book tour suspended, the COVID-19 crisis allowed me an opportunity to draw on my past expertise to fast-track this new book. 

If you haven’t seen it yet, we’ve put up a resource page all about COVID-19 with videos, links to my pandemic blog post and special Q&A sessions, a DIY hand sanitizer recipe, and more. Check it out here. And I’ve been doing a bunch of interviews lately, notably one with Moby and Joaquin Phoenix that you can watch here, as well as an article from Vox

New webinar – June 26

B12_recommendation_webinar_promotional_IGOn June 26th I’m going to be doing a 1.5-hour live webinar to explain the rationale for my new vitamin B12 recommendations and answer any questions you may have. I’ll start out with a discussion of the symptoms of B12 deficiency and then explain how I arrived at what I consider the optimal dose of vitamin B12 supplements in children, adults, the elderly, and during pregnancy. I’ll clarify why cyanocobalamin (not methylcobalamin) is the best type of vitamin B12 supplement and address the data suggesting B12 supplements cause acne, bone fractures, and lung cancer. I’ll also cover the healthiest food sources of B12 for those that don’t want to take supplements. I hope you’ll join me!

Register by making a donation of any amount through this form.

Registration ends: June 19
Webinar date & time: June 26, 2:00-3:30pm ET

 

Top 3 Videos of the Month 

 

COVID Q&A Thumbnail

COVID-19 Live Q&A

Replay of my COVID-19 Q&A last month.

 

 

Benefits of Quinoa for Lowering TriglyceridesBenefits of Quinoa for Lowering Triglycerides

How does the nutrition and health benefits of quinoa compare to whole grains, and does it aid in lowering triglycerides?

 

The Role of Processed Foods in the Obesity EpidemicThe Role of Processed Foods in the Obesity Epidemic

The rise in the U.S. calorie supply responsible for national weight gain and the obesity epidemic wasn’t just about more food, but a different kind of food – processed food.

 

Live Q&As May 28

Live Q&AEvery month now I do Q&As live from my treadmill, and Thursday, May 28 is the day.

  • Facebook Live: At 12:00 p.m. ET go to our Facebook page to watch live and ask questions.
  • YouTube Live Stream: At 1:00 p.m. ET go here to watch live and ask even more questions! 

You can now find links to all of my past live Q&As right here on NutritionFacts.org. If that’s not enough, remember I have an audio podcast to keep you company at http://nutritionfacts.org/audio.

 

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:

Mad Cow Disease and Cosmetics

As I discuss in my video Which Intestines for Food and Cosmetics?, the Food and Drug Administration (FDA) recently reopened comments about its policy of allowing some intestines, but not others, into the U.S. food supply. When the first few cases of mad cow disease started popping up, the FDA’s gut reaction was to ban all guts from food and personal care products. Then, in 2005, the U.S. Department of Agriculture and FDA amended their draft rule to “permit the use of the entire small intestine for human food” if the last 80 uncoiled inches going to the colon is removed. Since then, however, studies have shown that infectious mad cow prions can be found throughout all parts of the intestine, from the stomach down to the cow’s colon, raising the question of whether all entrails should be removed once again from the food supply.

The North American Meat Association said no, wanting to keep cattle insides inside the food supply. Similarly, the Cosmetic, Toiletry, and Fragrance Association (CTFA, now the Personal Care Products Council) protested the concern, arguing that banning downer and dead cattle, as well as their brains, skulls, eyes, spinal cords, intestines, and tonsils, could put our nation’s supply of cosmetics in jeopardy. There could be a tallow shortage for soap, for example. The FDA may not realize that cosmetics and personal care products are a quarter trillion-dollar industry worldwide.

In the end, the FDA “tentatively” concluded that intestines should continue to be allowed in the food and cosmetic supply because “[o]nly trace amounts of infectivity have been found” throughout the bowels of cattle. The agency had to come to that conclusion because, otherwise, the meat would have to be banned as well. Indeed, new research shows there’s mad cow infectivity in the animals’ muscles, too, and not just in the atypical cases of bovine spongiform encephalopathy (BSE), like the last mad cow found in California. We now know it’s in typical BSE as well: Low levels of infectious prions have also been found in the ribs, shoulders, tenderloins, sirloin tips, and round cuts of meat.

The latest estimates from Britain suggest 15,000 people are currently incubating the human form of mad cow disease, contracted through the consumption of infected meat. Fewer than 200 Brits have died so far of variant Creutzfeldt-Jakob disease, but the incubation period for this invariably fatal neurodegenerative disease—that is, the time between eating the meat and one’s brain filling up with holes—can be decades. The fact that so many people are carrying it has important implications for the safety of blood transfusions, which is why many Americans who’ve lived in England are barred by the Red Cross from donating blood. Also at risk is the safety of handling surgical instruments that may have cut into someone who’s a carrier, as it is so difficult to sterilize anything once it’s been contaminated.

Given these factors, it may be prudent to err on the side of caution when regulating which intestines are allowed on and in our mouths, but it’s a balance. As one meat company pointed out, guts are not just used for lipstick—intestines are human food, “providing us with a precious source of protein which is essential for our human population.”


Unfortunately, this is not the first time the FDA has caved to industry pressures. See, for example:

As scary as rare infections like mad cow disease are, we are much more likely to be disabled or killed by more conventional foodborne pathogens such as bacteria. Check out:

In health,
Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my free videos here and watch my live presentations: