It has long been thought that exercise is good for bones because the stress stimulates the bones to become stronger. Heavier people generally have higher bone mineral density (BMD), presumably due to the higher stress put on their bones.

Some time ago, I was giving a talk and mentioned that exercise is good for bones. Someone asked if you need to exercise your upper body in order for bones in your upper body to benefit from exercise. I didn’t know the answer; it didn’t seem unreasonable to me that any exercise could stimulate increased BMD via hormones circulating throughout the entire body.

I finally got around to looking into it today. I found a number of abstracts of experiments and meta-analyses looking at whether exercise improves BMD. Most indicated that exercise does improve BMD in certain spots, especially the hip and spine.

I only found one study that compared upper body exercise to lower body exercise:

Winters-Stone KM, Snow CM. Site-specific response of bone to exercise in premenopausal women. Bone. 2006 Dec;39(6):1203-9. Epub 2006 Jul 28.

People who did upper and lower body exercise had more improvement in their lower back BMD compared to people who only did lower body exercise. Unfortunately, it appears that they didn’t measure the spine in the upper back or other upper body areas which would have been interesting information.

This is just one study and I don’t think it’s conclusive, but so far it appears that at least some of your bones will benefit from doing upper body resistance exercise in addition to lower body exercise.

I just read a very engaging article about vitamin D (and that is saying a lot, I find most nutrition articles to be drowse-inducing). It is an interview with one of the world’s foremost vitamin D experts, Michael Holick. It is free on the web here.

A quick summary of the main points:

– 30 to 80% of the US population is vitamin D deficient.
– Vitamin D can protect against cancers, autoimmune diseases, infections, and bone problems.
– If you live north of Atlanta, your skin can’t make vitamin D from November through March.
– Both children and adults need 1,000 IU a day to keep their vitamin D levels above 30 ng/ml (about 75 nmol/L), which is the most healthy level.
– You need massive amounts of vitamin D to overdose. 5,000 IU per day, indefinitely, is probably safe.
– Vitamin D2 is as effective as D3.
– The sun is the most efficient way to receive vitamin D and may have important health benefits beyond vitamin D production.

For sun exposure, Dr. Holick says:

“I typically recommend people go out for a period of time—depending on the time of the year, the time of day, the latitude, and the degree of skin pigmentation—if you know you’re going to get a mild sunburn after 30 minutes, I typically recommend about 10, no more than 15, minutes of arms and legs exposure, or if you’re in a bathing suit, abdomen and back exposure as well, 2 to 3 times a week. Always wear sun protection on your face because that’s the most sun-damaged area and it’s only about 9% of your body surface, so it doesn’t provide you with that much vitamin D. Go out, enjoy yourself, get some sensible sun exposure, then put sunscreen on if you plan to stay out for a longer period of time. People with a higher degree skin pigmentation, such as African Americans, are walking around with an SPF of 8 to 15. That’s why they need to be exposed for much longer periods of time and why people of color are at especially high risk of having vitamin D deficiency.”

I have just updated VeganHealth.org with info on vegetarians’ vitamin D levels from the Adventist Health Study-2 which were recently released.

The good news is that vegetarians were no worse off than non-vegetarians. The bad news was that many of them were deficient, especially African Americans.

You can read more here.

And make sure you are following the vitamin D recommendations.

Medscape published a very interesting, short article yesterday, Diet, Nutrition, and Cancer — Don’t Trust Any Single Study. It is mostly an interview with Walter Willet, MD, DrPH, from the department of nutrition at Harvard School of Public Health. Among the topics covered are charred meat and the link between alcohol and breast cancer.

Unfortunately, you have to register in order to read it, but I think it’s worth it for anyone who is interested in this subject.

(Thanks, Maynard.)

Nothing earth-shattering, but I just updated VeganHealth.org with the nutrient intakes of vegetarian and vegans from a 2003 EPIC-Oxford paper.

I’ve referred to pieces of this information in other articles, so I finally decided to list it in one place.

Click here.

When I made my original post about plant food sources of vitamin A the other day, I completely forgot the largest source of all: carrot juice!

Carrot juice contains over twice the RDA in one cup – 2,256 RAE.

And I’ve added a few more foods to the Vitamin A page on VeganHealth.org.

Ginny Messina has written an interesting, short post about low-fat diets in response to my article about vegan diets and type 2 diabetes.

A week ago, a study was released showing that Seventh-day Adventist vegans have a 68% lower rate of type 2 diabetes than non-vegetarian SDAs. The finding was highly significant, with a confidence interval of .25 to .41. This is one of the most statistically significant findings I’ve ever seen from a nutrition study.

Where were all the media stories reporting this?!

There is one bit of caution – this study was cross-sectional, not prospective. That means we don’t know if the finding was because vegans don’t contract diabetes as often, or if people with, or prone to, diabetes are less likely to go vegan.

In addition to this SDA study, results were recently released from a study using a vegan diet to treat type 2 diabetes. The researchers found that a low-fat vegan diet resulted in lower body weight, cholesterol, triglycerides, blood glucose, and diabetes medications.

You can find more information in the article, Type 2 Diabetes and the Vegan Diet, that I just posted to VeganHealth.org.

A nutrient not many people think a lot about is vitamin A. I just updated VeganHealth.org with the vitamin A content of various plant foods. Take a look there and make sure you’re getting enough!

Every few years, another study comes out that shows vegetarian teens or young adults to have higher rates of eating disorders than non-vegetarians. The April 2009 issue of the Journal of the American Dietetic Association (JADA) has the most recent one: Adolescent and Young Adult Vegetarianism: Better Dietary Intake and Weight Outcomes but Increased Risk of Disordered Eating Behaviors.

Because eating disorders can result in serious illness, suffering, and death, I do not want to downplay the importance of studying them. However, given that a vegetarian diet is promoted and generally thought of as a good way to lose weight, it should come as no surprise to anyone to find that vegetarians have a higher rate of disordered eating behaviors since many young people try the diet in order to lose weight.

In this study, the researchers’ definition of vegetarian included anyone who had considered themselves vegetarian for over one month, whether they really were vegetarian or not; 25% ate chicken and 46% ate fish. And to be considered someone who engages in disordered eating behavior, all someone had to do was exhibit an unhealthy weight-control behavior or binge eating one time in the previous year.

It’s not surprising that many people who engage in disordered eating behaviors will at some point call themselves vegetarian for at least a month. When you draw a cross section of everyone who is seriously dieting combined with everyone who has cut out at least red meat, you are bound to find some overlap between the two groups.

To actually study if going vegetarian causes people to develop eating disorders, you need to start with a group of people (some vegetarian) who have not previously engaged in disordered eating behaviors and then follow such people through time to see if the vegetarians are more likely to develop eating disorders.

In better news, among the older cohort in the JADA study, current vegetarians were less likely than never vegetarians to be overweight (17% vs 28%) or obese (6% vs 14%), and vegetarian adolescents and young adults reported the highest fruit and vegetable intake. The authors observed that current vegetarian adolescents appear to be at decreased risk for using alcohol, cigarettes, and other drugs.

To be frank, I would guess that even among people without a previous history of eating disorders, vegetarians are more likely to develop orthorexia, an eating disorder characterized by excessive focus on eating healthy foods. We should be aware of this possibility.

Here are two videos on orthorexia:

Part 1
Part 2

Erik Marcus and Ginny Messina have also written good posts on this JADA study.