By Marji McCullough, ScD, RD
You may be aware that Vitamin D is important for helping make strong bones. But vitamin D often appears in the media because of its potential role in a host of other health effects, from preventing cancer, diabetes, and heart disease to simply living longer. However, most of these “non-skeletal” (not having to do with your bones) roles of vitamin D are not clearly established and remain a topic of active investigation and debate. To add to the confusion, several recent scientific reviews of the vast data on vitamin D arrived at different conclusions about whether it helps prevent disease or not.
In this blog, I am going to focus on the evidence on vitamin D and cancer prevention, highlight some key unresolved questions, and give some advice to consider while we await more solid answers (which may take a while).
Where does vitamin D come from?
People can get vitamin D from exposure to sunlight, from certain foods, and from supplements.
Current vitamin D recommendations from the Institute of Medicine (IOM), the organization tasked with developing the Recommended Dietary Allowances (RDAs), are 600 International Units (IU) per day for most adults, and 800 IU of vitamin D per day for those over age 70.… Continue reading →
By Gery P. Guy Jr., PhD, MPH
If you read no further, know this: there is no such thing as a safe tan. Indoor tanning is just as dangerous, if not more, than tanning outside in the sun. In fact, indoor tanning injures thousands of people each year badly enough to go to the emergency department. Indoor tanning can cause sunburn and damage to your eyes that could lead to vision loss. Indoor tanning can also cause premature skin aging, including loss of elasticity, wrinkling, age spots, and changes in skin texture.
Most dangerous of all, indoor tanning is a recognized cause of skin cancer, including deadly melanoma. Skin cancer is the most common form of cancer in the United States. Approximately 3.5 million cases of non-melanoma skin cancers are treated each year, and more than 70,000 melanomas are diagnosed yearly. While many cancers have been on the decline in recent years, rates of melanoma, which causes the most skin cancer-related deaths, have been on the rise. Increased exposure to ultraviolet radiation (UV) through indoor tanning may be partially responsible for the continued increase in melanoma, especially among young women. Indoor tanning is particularly dangerous for younger and more frequent users.… Continue reading →
By Ted Gansler, MD, MPH
Like other contributors to the Expert Voices blogs, I am occasionally asked to reply to questions from journalists about various cancer-related topics. The most recent question I received is whether it is true that women who carry a cell phone in their bras are at increased risk for developing breast cancer.
This kind of question is surprisingly difficult to answer. It’s relatively easy to write about things that are known to cause cancer. It’s more difficult to be confident that something does not cause cancer, but one can still provide some guidance if there have been at least a few carefully-conducted epidemiologic studies with negative results. The most challenging requests we receive are often about questions that researchers have not addressed by scientific studies of humans populations. This is one such question.
Cause or Coincidence?
There are a few known instances of breast cancer in young women who have kept cell phones in their bras. (Even when cell phones are not being used for conversation or texting, if they are on then they still periodically emit low energy electromagnetic signals to stay in touch with nearby cell towers.) Because breast cancer is an uncommon and tragic occurrence among young women, these cases have received significant attention on television and on the Internet.… Continue reading →
By Marji McCullough, ScD, RD
EDITOR’S NOTE: Dr. McCullough added the following statement 4/8/14 in response to questions related to sources of isoflavones:
Research on soy and cancer is highly complex, controversial, and evolving.
When concerns about soy are raised, they generally focus on findings from rodent models of cancer which tend to use isolated soy compounds like soy protein isolate or high doses of isoflavones (compounds found in soy). However, soy is metabolized differently in humans than it is in mice and rats, so findings in rodents may not apply to people. (See: http://www.ncbi.nlm.nih.gov/pubmed/16614407 for more on this.)(Setchell, AJCN, 2011). There is no evidence in the medical literature that soy protein isolate is bad for humans, compared to other forms of soy. Soy protein isolate is often used as a supplement in randomized studies of the effects of soy on health and none of these studies have shown harm.
Most of the studies suggesting benefits of soy consumption in people have measured how much soy foods people are eating, including tofu, soybeans, and soy milk. These foods are more commonly eaten in Asian countries. In the U.S., purified forms of soy are used in the food supply, including in energy bars and soy hot dogs. The few US studies that have measured these forms of soy do not suggest harm.… Continue reading →
By Ted Gansler, MD, MBA, MPH
You have probably seen and heard a lot about breast cancer during the past few weeks, but as we approach the end of this year’s breast cancer awareness month this is a good time to ask how much of the information you encountered is actually true. See if you know which of the following statements are true and which are false… [more]
TRUE OR FALSE: Most breast cancer is hereditary. You don’t need to worry if you don’t have a family history of breast cancer.
FALSE. Only about 5% to 10% of breast cancer cases are thought to be the result of gene defects (called mutations) inherited from a parent. The lifetime risk for breast cancer can be as high as 80% for members of some families who inherit certain mutations of BRCA genes. The risk is not nearly as high for most women with a family history of breast cancer. On average, having 1 first-degree relative (mother, sister, or daughter) with breast cancer approximately doubles a woman’s risk, and having 2 first-degree relatives triples her risk. About 20% to 30% of women with breast cancer have a family member with this disease (although most of these families do not have abnormal BRCA genes).… Continue reading →
By Marji McCullough, ScD, RD
Editor’s note: Dr. McCullough added the following statement 12/20/13 in response to new studies being released:
Recent findings on multivitamin supplements published after the posting of this blog deserve mention. In 2012, the results of a randomized controlled trial (RCT) of a daily multivitamin supplement were published, showing a small but statistically significant lower risk of all cancers combined in male physicians followed over 11 years. The supplement included 30 nutrients at levels similar to that found in a regular diet in the United States (≤100% recommended daily allowance (RDA)). The U.S. Preventive Services Task Force (USPSTF) recently updated their review of vitamin and mineral supplements for the primary prevention of cancer and cardiovascular disease (CVD) and found there isn’t much evidence that multivitamins or supplements help prevent cancer or CVD. But they add that a small benefit from multivitamin supplements on cancer in men was found, based on this study and an earlier RCT in France. The study in France found lower rates of cancer in men, but not women. The authors speculate that this may have been due to worse nutritional status – a generally less nutritious diet in the men – but more research is needed.… Continue reading →
By Ted Gansler, MD, MBA
An e-mail message that may have come into your inbox recently claims that dangerous levels of a cancer-causing chemical (benzene) are released from the plastic surfaces of automobile interiors. The e-mail recommends opening the vehicle’s windows to remove the benzene before using the air conditioner.
Although benzene is linked to leukemia, very little research has looked at whether the interior surfaces of cars release dangerous amounts of benzene, and the information that is available does not support the e-mail’s claims. [more]
Let’s break the message down and compare the claims with the facts.
Here is the e-mail message (this links to snopes.com, which is not affiliated with cancer.org or ACS)
And here’s a point-by-point comparison of the claims and the facts:
Claim: My car’s manual says to roll down the windows to let out all the hot air before turning on the A/C. WHY?
Fact: On a sunny day, the temperature in a parked car can be more than 40 degrees (Fahrenheit) higher than the outside air. Opening the windows is the fastest way to exchange the hot interior air with the cooler outside air. Once that is done, the air conditioner can make the interior cooler than the outside air.… Continue reading →
By Katherine Sharpe, MTS
“It might be time to consider a clinical trial.” I have heard this many times in my work with the American Cancer Society. Unfortunately, in most cases, people think of clinical trials as the option of last resort, so they consider one only when all other treatment options have failed.
But the truth is that clinical trials should always be considered as a treatment option. In fact, there are clinical trials for almost every type of cancer and stage of disease – there are even clinical trials for cancer prevention! Without clinical trials, we would see virtually no advances in cancer treatment.
The good news is that more and more people are considering a cancer clinical trial when they are first diagnosed – and that helps speed up breakthroughs in cancer care. But there is clearly a need for more people to learn about and consider this option.
Take a look at pediatric cancer. When I was growing up in the 1970’s, there were several books that highlighted the stories of teenagers diagnosed with leukemia. Unfortunately, most of these stories didn’t end well. However, since the 1970’s, the cure rate of acute lymphoblastic leukemia (ALL) has gone from 30% to 80%, largely due to advances discovered during cancer clinical trials.… Continue reading →