- In Brief: Do Kids and Adults Walk Alike?
- Exercise Combats Cancer Fatigue
- Keeping the Weight Off: It Happens
- Healthy Eating Links to Breast Survivors Health
Science in the Spotlight:
Vitamin D for Cancer Prevention: No Supplements Needed
The relatively high levels of vitamin D some studies suggest may fight cancer along with other diseases are not supported by a review of the research and could be harmful in some cases, finds a new report by the Institute of Medicine.
The report supports AICR’s recommendation that people, in general, should not rely on supplements to protect against cancer.
"As a cancer researcher I enthusiastically joined [the committee] thinking that the cancer outcomes would be important indicators in our consideration and that they may give us guidance as to what population-based recommendations would be," said Steven K. Clinton, M.D., Ph.D. at a news conference. Dr. Clinton, a Professor at the Division of Medical Oncology at Ohio State University and one of the 14 experts on the IOM committee, is also a previous AICR-grantee who has presented at AICR’s Annual Research Conference. "When we did a thorough, comprehensive all-inclusive review of the data, it was far less consistent than I had originally thought."
The IOM guidelines did raise the RDAs from the amount last recommended 13 years ago, for bone health alone. RDA levels are now 600 international units (IU) for people ages 1-70, and 800 IU for adults older than 70. The older vitamin D guidelines call for an RDA of 200 IU a day for people up to age 50, 400 IU a day for those ages 51 to 70, and 600 IU a day for those older than age 70. IOM reference values provide the scientific basis for the food guidelines in both the United States and Canada.
Beyond Bone Health
The research on vitamin D and calcium maintaining bone health is clear. (Vitamin D helps the body absorb calcium.) But during the last decade, scientists have conducted a flurry of studies investigating vitamin D’s role beyond bone disorders, including preventing cancer, diabetes, heart disease and other chronic diseases. The studies have led to reports that Americans have inadequate levels of vitamin D and made testing patient’s vitamin D levels a common practice.
Yet after reviewing nearly 1,000 studies as well as testimony from scientists, the expert IOM committee found the evidence does not show vitamin D has effects beyond skeletal growth and maintenance.
"For all of us to look at this data in its entirety and review in a clinical manner, what it has done is stimulated a lot of thought about future research," said Dr. Clinton.
Also, the majority of Americans and Canadians are getting enough vitamin D and calcium, the committee determined from reviewing national surveys of blood levels. Some adolescent girls may not get enough calcium, and there is a greater chance that elderly individuals may fall short of the needed amounts of calcium and vitamin D. Vitamin D deficiency may be overestimated because many labs appear to be using cutpoints higher than the evidence indicates are appropriate. Based on the data, almost all individuals get sufficient vitamin D when their blood levels are at or above 20 nanograms per milliliter.
Food and Sun
We get vitamin D through food, sunlight, and supplements. Sunlight triggers the production of vitamin D but because sun exposure varies greatly among individuals and can cause serious health problems, the new intake levels for vitamin D are based on individuals who get minimal sun exposure.
Watch Dr. Clinton talk about AICR’s influence on his work and future research.
Foods naturally containing vitamin D include salmon, tuna, and egg yolks (see chart). Americans consume much of their dietary vitamin D through fortified foods, which include milk, many yogurts, and cereals.
Evidence about risks associated with routine vitamin D supplementation is still tentative, and most studies have focused on extremely high doses over a short time period. For vitamin D, the IOM set the upper intake levels at 4,000 IUs daily (over age 8), finding the risk of harm increases beyond this level. But between the RDA and 4,000 IUs, the experts point out, there is no recognized health benefit.
Like all public health recommendations, there are cases where individuals may need Vitamin D (or calcium) supplementation. For people in treatment for chronic disease and others specialized populations or for anyone in doubt, individuals should discuss vitamin D with their health practitioner.
You can read the full report on the IOM Website.
Selected Food Sources of Vitamin D
IUs per serving*
|Cod liver oil, 1 tablespoon||
|Salmon (sockeye), cooked, 3 ounces||
|Mackerel, cooked, 3 ounces||
|Tuna fish, canned in water, drained, 3 ounces||
|Milk, nonfat, reduced fat, and whole, vitamin D-fortified, 1 cup||
|Orange juice fortified with vitamin D, 1 cup (check product labels, as amount of added vitamin D varies)||
|Yogurt, fortified with 20% of the DV for vitamin D, 6 ounces (more heavily fortified yogurts provide more of the DV)||
|Margarine, fortified, 1 tablespoon||
|Sardines, canned in oil, drained, 2 sardines||
|Liver, beef, cooked, 3.5 ounces||
|Ready-to-eat cereal, fortified with 10% of the DV for vitamin D, 0.75-1 cup (more heavily fortified cereals might provide more of the DV)||
|Egg, 1 whole (vitamin D is found in yolk)||
|Cheese, Swiss, 1 ounce||
* IUs = International Units
Do Kids and Adults Walk Alike?
A new equation that calculates the energy we use when walking shows that walkers of all heights use the same amount of energy per stride, with kids tiring faster than taller people because they need to take more steps to cover the same distance.
The researchers measured the metabolic rates of children and adults, ages 5 to 32 and weighing between 15.9kg and 88.7kg. They compared the way each person walked, measuring the stride, stride duration, and proportion of each stride spent in contact with the ground to find out if large and small people walk differently. The analysis showed that all the walkers moved in exactly the same way, regardless of their height. The researchers also developed an equation to calculate exactly how much energy walkers use.
Source: Weyand, P. G., Smith, B. R., Puyau, M. R. and Butte, N. F. (2010). The mass-specific energy cost of human walking is set by stature. J. Exp. Biol. 213, 3972-3979.
Cancer-related fatigue (CRF) is one of the most common reported side effects of cancer treatment, with symptoms lasting from weeks to years after treatment and harming quality of life. Now, a review of the research suggests that exercise reduces CRF, particularly among breast and prostate cancer survivors and those of older ages.
In the analysis, published in Cancer, Epidemiology, Biomarkers and Prevention, the researchers found 44 randomized controlled studies examining CRF among survivors. The studies included survivors of any cancer type and different stages of treatment, including those who had completed treatment.
After analyzing data from the studies, researchers found that exercise reduced CRF among cancer survivors engaging in moderate intensity, resistance exercise reduced CRF more than those exercising at lower intensity resistance of aerobic exercise. Age was also related to reduced CRF, with older cancer survivors reducing CRF more than younger survivors engaging in any form of exercise.
Source: Justin C. Brown et al. Efficacy of Exercise Interventions in Modulating Cancer-Related Fatigue among Adult Cancer Survivors: A Meta-Analysis. Cancer Epidemiol Biomarkers Prev. 2010 Nov 4.
More than one of every six US adults who has been overweight or obese has lost weight and kept it off for at least one year, finds a new study published in the International Journal of Obesity. The rate of successful weight maintenance is higher than many weight-loss trials and observational studies report, notes the study, suggesting that adults may be more successful at losing and sustaining weight loss than previously thought.
The study analyzed data from approximately 14,000 overweight or obese participants of the 1999-2006 National Health and Nutrition Examination Survey, in which weight history was self-reported. Researchers calculated participants’ BMI and whether they lost 5, 10, 15 or 20 percent of their body weight and then maintained that weight loss long-term (longer than one year). One-third of participants stated a goal was to lose weight.
Overall, 36 percent of those overweight or obese had maintained a weight loss of at least 5 percent of their initial body weight for a year; 17 percent maintained a 10 percent weight loss; and 4 percent a 20 percent weight loss. In the sample, women, adults age 75 to 84, non-Hispanic whites and patients with diabetes had a higher prevalence of long-term weight loss management. Although the study is encouraging, note the authors, with two-thirds of the US population overweight or obese more research is needed in determining how individuals successfully achieved weight loss.
Source: J L Kraschnewski1, et al. Int J Obes (Lond). Long-term weight loss maintenance in the United States. 2010 Nov;34(11):1644-54.
Breast cancer survivors who eat plenty of fruits, vegetables and whole grains have fewer signs of chronic inflammation, finds a new study that suggests a healthy diet may lead to improved survival.
Previous studies have linked poorer breast cancer survival to measures of chronic inflammation – such as blood concentration of C-reactive protein (CRP). The link between diet quality and changes in inflammation could be direct or indirect through changes in body mass: chronic inflammation is linked strongly with obesity, and obesity convincingly increases the risk of postmenopausal breast cancer.
Published in Cancer, Epidemiology, Biomarkers and Prevention, the study evaluated the diet quality of almost 750 breast cancer survivors, taken at 6 months and 30 months after diagnosis. Researchers also gathered information on the women’s activity levels. At the 30-month mark, measures of inflammation from the women’s blood found that inactive women with better quality diets had lower levels of CRP, but levels of other signs of inflammation remained unchanged.
Source: Source: George SM et al. Cancer Epidemiol Biomarkers Prev. Postdiagnosis Diet Quality Is Inversely Related to a Biomarker of Inflammation among Breast Cancer Survivors. 2010 Sep;19(9):2220-8.
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