Monthly Archives: August 2016
I have discussed this the risks of calcium supplements previously, and now we find out that they do not do much good anyway. See my posts of 22nd July, 2015(calcium Doctors slam calcium and Vitamin D conflict of interest) and June 14th 2013 (calcium -Calcium confusion: scientists divided over supplements), Jan 12 2012 (calcium Link between calcium supplements and heart disease raises the question: Take them or toss them?) and other posts.
Calcium Intake and Bone Mineral Density
Dietary sources vs supplements
October 13, 2015
An increase in calcium intake either from dietary sources or from calcium supplements produced only small, non-progressive increases in bone mineral density (BMD) which is unlikely to translate into clinically significant reductions in fractures, according to a meta-analysis of 59 randomized controlled trials in participants aged 50 years and older. The study found:
• Increasing calcium intake from dietary sources increased BMD by 0.6% to 1.0% at the total hip and total body at 1 year and by 0.7% to 1.8% at these sites and the lumbar spine and femoral neck at 2 years.
• Calcium supplements increased BMD by 0.7% to 1.8% at all 5 skeletal sites at 1, 2, and over 2½ years, but the size of the increase in BMD at later time points was similar to the increase at 1 year.
• Increases in BMD were similar in trials of dietary sources of calcium and calcium supplements, in trials of calcium monotherapy vs co-administered calcium and vitamin D, in trials with calcium doses of ≥1000 mg/day vs <1000 mg/day, and ≤500 mg/day vs >500 mg/day.
Citation: Tai V, Leung W, Grey A, Reid IR, Bolland MJ. Calcium intake and bone mineral density: systematic review and meta-analysis. BMJ 2015;351:h4183. doi:10.1136/bmj.h4183.
Commentary: This meta-analysis of 59 randomized controlled trials of both dietary and supplemental calcium strongly suggests that the standard advice of increasing calcium intake is likely to yield little to any benefit on either BMD or risk of fracture in post-menopausal women. This low likelihood of benefit must be viewed in the context of reported increase in cardiovascular risk and the increased risk of kidney stones associated with increased calcium intake.1,2,3 This is another example of an intervention that intuitively makes complete sense which turns out not to be so after careful examination under the scrutiny of randomized trials. —Neil Skolnik, MD
1. Bolland MJ, Barber PA, Doughty RN, et al. Vascular events in healthy older women receiving calcium supplementation: randomised controlled trial. BMJ 2008;336:262-266.
2. Bolland MJ, Avenell A, Baron JA, et al. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ 2010;341:c3691.
3. Jackson RD, LaCroix AZ, Gass M, et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med 2006;354:669-683.
A Personalized Diet, Better Suited to You
By Kate Murphy January 11, 2016 3:59 pm January 11, 2016 3:59 pm
Credit Tamara Shopsin
In what has come to feel like a twice-a-decade mea culpa, the federal government last week released another revision of the Dietary Guidelines for Americans, this time urging many of us to consume less sugar and less protein. The new recommendations may well influence nutrition labeling, school lunches and government assistance programs.
But the advice is likely to be ignored by much of the I’ll-have-fries-with-that citizenry. Moreover, recent scientific findings are beginning to lend support to a new approach to diet, one personalized to the individual.
Research increasingly suggests that each of us is unique in the way we absorb and metabolize nutrients. This dawning realization has scientists, and entrepreneurs, scrambling to provide more effective nutritional advice based on such distinguishing factors as genetic makeup, gut bacteria, body type and chemical exposures.
“The same dietary advice cannot be good for everyone, because we are all different,” said Eran Elinav, an immunologist at the Weizmann Institute of Science in Rehovot, Israel. “This is why we have failed so miserably at controlling the obesity epidemic.”
Dr. Elinav and his colleagues are hoping to build a new kind of diet-counseling business from findings they published recently in the journal Cell. Their study found a startling variation in the glucose responses of 800 subjects fed the same foods. Some participants had sharp increases in blood sugar when they ate ice cream and chocolate, while others showed only a flat or moderate response.
Wild variations also occurred when the subjects ate foods like sushi and whole-grain bread, making a mockery of the glycemic index, long used to rank foods according to their effects on blood sugar, and calling into question the reliability of calorie calculations. Each person’s capacity to extract energy from foods differs, it appears.
But the Weizmann team took their findings a step further.
By combining data gleaned from subjects’ glucose responses with information about their gut bacteria, medications, family histories and lifestyles, the scientists devised an algorithm that accurately predicted blood sugar responses to foods the participants hadn’t yet eaten in the study.
Further, with the algorithm the scientists were able to prescribe personalized diets to a group of 100 prediabetic patients that significantly moderated their blood sugar following meals and boosted levels of good bacteria in their guts.
“The algorithm is similar to what Amazon uses to tell you which books you want to read,” said Eran Segal, a computer scientist at the Weizmann Institute and co-author of the study. “We just do it with food.”
Although they have more fine-tuning to do, Dr. Segal said his group hope to eventually use this algorithm to customize dietary advice to the public. Indeed, personalized nutritional counseling is a burgeoning field. Several companies, including Vitagene, Nutrigenomix and DNAFit, are already offering individualized dietary counseling.
Their efforts are based mostly on genetic testing, but scientists have only just begun to explore the links between DNA and good nutrition. “I think companies offering personalized dietary advice are probably running ahead of the evidence,” said John Mathers, director of the Human Nutrition Research Center at Newcastle University in Britain.
More research is needed, he and other experts say, because the interactions among one’s genes, microbiome, diet, environment and lifestyle are so infinitely complex.
Scientists are beginning to tease out the connections. Studies have linked at least 38 genes to nutrient metabolism — variants of which are thought to hinder or help absorption or the efficient use of nutrients in foods. Depending on your genetic makeup, studies suggest you might want to consume more or less folate, choline, vitamin C, fatty acids, starches and caffeine.
“We’re starting to see what links there are between food, microbiota, individual genetic makeup and our health,” Dr. Mathers said. “These different lines of work are beginning to come together now partly because we have the technology to cope with the big data issues.”
Dr. Mathers is the lead investigator of a six-month study, funded by the European Union, called Food4Me. Some 1,500 participants in seven European countries were randomly given personalized dietary advice based on their genetic data, or told to follow standard dietary prescriptions like eating lots of fruits and vegetables, lean meats and whole grains.
While the results haven’t been published yet, Dr. Mathers said, “the bottom line is those who were in the personalized diet cohort did better than those in the one-size-fits-all diet group, making us pretty confident personalized diets are the way forward.”
Still, gene expression, the microbiome and other factors used to personalize diets are not immutable: They may be altered not only by foods, but also by factors like stress and chemical exposures, changing by the year, month or even week.
Companies that provide personalized dietary counseling counter that there is at least enough evidence to improve upon all-purpose dietary recommendations, which have proved largely unsuccessful.
Ahmed El-Sohemy, an associate professor and nutrigenomics researcher at the University of Toronto and a co-founder of Nutrigenomix, offered coffee as an example. Current guidelines advise no more than four or five cups per day.
“That’s fine for roughly half the population that are fast metabolizers,” he said. “For the other half who have a variant of the CYP1A2 gene, any more than two cups per day will increase the risk of a heart attack and hypertension.”
Companies like Nutrigenomix tend to offer mostly nutritional advice, rather than diets to treat specific diseases, and therefore the Food and Drug Administration does not regulate this new and potentially lucrative business. (Enforcement would be tough anyway, as many providers are based in other countries.)
So buyers beware. Discuss any prescribed dietary changes with a doctor or registered dietitian.
Tellingly, many of the experts who champion the future of personalized nutrition have not been genetically tested themselves, nor have they had their own microbiota analyzed.
“I like to enjoy my food,” Dr. Mathers said. “That’s where I start.”
Panel Reasserts Mammogram Advice That Triggered Breast Cancer Debate
By DENISE GRADYJAN. 11, 2016
Dr. Michael LeFevre, a former chairman of the United States Preventive Services Task Force, said younger women have to make decisions for themselves about mammography. Credit Daniel Brenner for The New York Times
In 2009, an influential panel of medical experts ignited a nationwide uproar by suggesting that women needed fewer mammograms than had long been recommended. Instead of starting at age 40 and being screened every year, women with average risk of breast cancer could safely begin at 50 and be tested every other year, the group said, citing extensive data to support its advice. It also said that after 74, there was not enough evidence to determine whether routine mammography was worthwhile.
Outrage ensued, from advocates for screening who said the advice would lead to delayed diagnoses and deaths.
On Monday, the same panel issued an update of its guidelines — and it is sticking to its guns. The basic advice, which applies to women with an average risk of breast cancer, was unchanged.
The recommendations are not immediately expected to affect insurance coverage. In December, Congress passed a bill requiring private insurers to pay for screening mammograms for women 40 and over every one to two years without copays, coinsurance or deductibles, through 2017.
But advocacy groups said they were worried about what will happen after 2017. “It would be great if screening could be covered forever,” said Carli Feinstein, chief of staff for Bright Pink, a national group focused on prevention and early detection of breast and ovarian cancer.
The Susan G. Komen for the Cure foundation also expressed concerns about insurance payment, and issued a statement saying that a lack of coverage would hit “high risk and underserved” women hardest, particularly black women, who are more prone than whites to aggressive types of breast cancer.
The panel issuing the guidelines is the United States Preventive Services Task Force, an independent board of doctors and other experts appointed by the Department of Health and Human Services to evaluate screening tests, counseling and medications intended to prevent disease or detect it early. Panel members are volunteers, and consider only the scientific evidence in their evaluations, not cost or insurance coverage.
The mammography guidelines, along with four editorials and seven supporting articles, were published on Monday in the Annals of Internal Medicine.
The task force emphasized that it was not advising against screening for women under 50 or over 74, or against screening every year as opposed to every other year. Rather, it says that women should choose for themselves — but that its guidelines offer the best overall balance of benefits and risks.
The task force also examined data for two subjects not included in its 2009 report, and concluded that there was not enough evidence to recommend for or against either of them. One was additional testing, such as M.R.I. or ultrasound, for women with “dense” breast tissue, which makes it difficult to detect tumors with mammography. The other was screening with a newer test called 3-D mammography or digital breast tomosynthesis.
Breast cancer is the second-leading cause of cancer death in women in the United States, after lung cancer. In 2015, there were about 232,000 new cases of breast cancer, and 40,000 deaths. The highest incidence is in women aged 55 to 64.
Dr. Constance Lehman, a professor of radiology at Harvard Medical School and director of breast imaging at Massachusetts General Hospital, who is not on the task force, said she was pleased to see that although its advice had not changed, the group had placed more of an emphasis than before on the importance of women’s having the freedom to decide how often to be screened and when to start.
The guidelines state that from ages 40 to 74, screening will reduce the odds of dying from breast cancer, with women 40 to 49 benefiting the least and those 60 to 69 benefiting the most. The task force said it concluded “with moderate certainty” that the benefit was moderate in women 50 to 74 and small in women 40 to 49.
For every 10,000 women screened repeatedly over 10 years, four lives are saved in women 40 to 49; eight in women 50 to 59; 21 in women 60 to 69; and 13 in women 70 to 74, the task force found.
“The science supports mammography as an important tool in the fight against breast cancer,” said Dr. Michael LeFevre, a former chairman of the task force and a professor of medicine at the University of Missouri. He noted that breast cancer deaths have decreased since mammography came into widespread use in the 1980s, though some of the decline, he said, was also due to better treatments. “We believe the benefits increase with age. But there are harms, and particularly in their 40s, women have to make a decision for themselves.”
One potential harm is false positives, in which a suspicious mammogram finding leads to more tests, sometimes even biopsies, but turns out to be harmless. The guidelines relied in part on a study of records from 405,191 women who had digital mammograms from 2003 to 2011, which found that false positives were common, especially in younger women. Among those 40 to 49 who had regular screening, for every 1,000 women tested, 121.2 had a false positive.
Another study, in 2011, found that 61 percent of women who had yearly mammograms starting at age 40 had at least one false positive by the time they were 50. Being tested every other year instead of every year cut the rate of false positives significantly, to about 42 percent.
Another potential risk is overdiagnosis, meaning that some of the tiny cancers found in mammograms might never progress or threaten the patient’s life. But because there is now no way to be sure which cancers will turn dangerous, they are treated anyway. Researchers agree that overdiagnosis occurs, but they do not know how often.
Dr. Therese Bevers, medical director of the Cancer Prevention Center at the University of Texas MD Anderson Cancer Center in Houston, said she thought the task force overemphasized the importance of drawbacks like false positives.
Dr. Clifford A. Hudis, the chief of breast cancer medicine at Memorial Sloan Kettering Cancer Center, also expressed concern: “The harm of a missed curable cancer is something profound. The harm of an unnecessary biopsy seems somewhat less to me.”
Leading medical groups offer different advice about screening that leaves women and their doctors to puzzle it out for themselves. The National Comprehensive Cancer Network, an alliance of prominent cancer centers, recommends mammograms every year starting at age 40. The American College of Obstetricians and Gynecologists recommends them every year or two from ages 40 to 49, and every year after that.
In October, one of the most influential groups, the American Cancer Society, dialed back its advice. Although for many years the society recommended mammograms once a year starting at age 40, it now advises that screening start at 45, continue yearly through 54 and then shift to every other year.
Recognizing the confusion, the cancer society, the cancer network and other groups will attend a private meeting in Washington on Jan. 28 and 29 to try to produce a single set of guidelines.
Representatives from the preventive services task force will attend, but the task force cannot sign onto consensus statements. It can change its advice only by issuing new guidelines, Dr. LeFevre said.
Hormone replacement therapy after menopause and risk of breast cancer in BRCA1 mutation carriers: a case–control study
Breast Cancer Research and Treatment, 02/02/2016
This study suggest that a short course of HRT should not be contra–indicated for BRCA1 mutation carriers who have undergone menopause and who have no personal history of cancer.
- The researchers conducted a case–control analysis of 432 matched pairs of women with a BRCA1 mutation.
- Detailed information on HRT use after menopause (duration, type, age at first/last use, formulation) was obtained from a research questionnaire administered at the time of study enrollment.
- Conditional logistic regression was used to estimate the odds ratio (OR) and 95 % confidence intervals (CI) associated with HRT use.
- The mean duration of HRT use after menopause was 4.3 years among the cases and 4.4 years among the controls (P = 0.83).
- The adjusted OR for breast cancer comparing all women who ever used HRT to those who never used HRT was 0.80 (95 % CI 0.55–1.16; P = 0.24).
- Findings did not differ by type of menopause (natural vs. surgical), by recency of use, by duration of use, and by formulation type.
Ask Well: The Sugar in Fruit
By Sophie Egan
February 10, 2016 5:45 am February 10, 2016 5:45 am 48 Comments
Does the sugar in fruit cause insulin to spike in the same way as regular sugar?
Not if the fruit in question is whole fruit. Unlike honey, cane sugar, high-fructose corn syrup and other forms of sugar that are added to many processed foods, the sugar naturally found in fruit is consumed in the company of fiber, which helps your body absorb the sugar more slowly.
When you consume a food or beverage that contains carbohydrates, your digestive system breaks the carbs down into a type of sugar called glucose, which enters the bloodstream. When blood sugar levels rise, the pancreas produces the hormone insulin, a signal to your cells to absorb the glucose so it can be used immediately as energy or stored in the liver and muscles for later use. Repeatedly eating foods that cause surges in blood sugar makes the pancreas work harder. Over time, that can lead to insulin resistance and an increased risk of Type 2 diabetes.
Refined grain products like white bread, crackers, and cookies, which tend to be low in fiber, deliver large amounts of carbohydrates per serving and are digested very quickly, raising blood sugar and insulin levels. Sugars enter into the bloodstream especially rapidly when you consume carbohydrates in liquid form, such as in sugary sodas.
But it’s not as simple as adding fiber to starchy foods or soda — the quality and physical form of carbohydrates are critical, which means favoring whole foods over processed foods and added sugars. That includes favoring whole fruit over fruit juice: Fruit juices can contain fiber, but some of that fiber is broken down in the juicing process, reducing the metabolic benefit compared with intact fruit.
To minimize spikes in insulin, it’s best to eat fruit whole. That’s because with whole fruit the cell walls remain intact, said Dr. David Ludwig, director of the New Balance Foundation Obesity Prevention Center at Boston Children’s Hospital. This is how fiber can offer the greatest benefit, he explained, because the sugars are effectively sequestered within the fiber scaffolding of the cells, and it takes time for the digestive tract to break down those cells. Four apples may contain the same amount of sugar as 24 ounces of soda, but the slow rate of absorption minimizes the blood sugar surge.
“If we take a nutrient-centric approach, just looking at sugar grams on the label, none of this is evident,” Dr. Ludwig said. “So it really requires a whole foods view.”
Do you have a health question? Submit your question to Ask Well.
Sophie Egan is the director of programs and culinary nutrition for strategic initiatives at the Culinary Institute of America. She is the author of the forthcoming book “Devoured: From Chicken Wings to Kale Smoothies — How What We Eat Defines Who We Are” (William Morrow, May 2016).