Article Content



* Does Personalized Nutrition Improve Health of Adults?


* Effect of Absorption of [beta]-Carotene on Serum Cholesterol



The Mediterranean (MED) diet-rich in olive oil, fruits, vegetables, legumes, nuts, and seeds-has been a recommended way to reduce the risk of heart disease, type 2 diabetes, and other adverse health outcomes. But exactly how and why the MED diet lowers risk for type 2 diabetes has remained unclear. In a study conducted by investigators from Brigham and Women's Hospital in Boston, researchers examined outcomes for more than 25,000 participants in the Women's Health Study, a longitudinal cohort study that followed female health professionals for more than 20 years. The team examined several biomarkers to look for biological explanations for these results, finding key mechanisms including insulin resistance, body mass index, lipoprotein metabolism, and inflammation. The investigators report that women who adhered to a more MED-like diet had a 30% lower rate of type 2 diabetes than women who did not.


Using a food frequency questionnaire, they assigned each participant a MED diet intake score from 0 to 9, with points assigned for higher intake of fruits, vegetables, whole grains, legumes, nuts and fish, moderate intake of alcohol, and lower intake red meat or processed meat. The team measured a range of biomarkers, including traditional ones such as cholesterol. They also measured more specialized lipoproteins that that pack and transport fats and proteins and measure of insulin resistance.


Of the more than 25,000 participants in the Women's Health Study, 2,307 developed type 2 diabetes. Participants with higher MED intake at the beginning of the study (scores >=6) developed diabetes at rates that were 30% lower than that of participants with lower MED intake (<=3). This effect was seen only among participants with a body mass index greater than 25 (overweight or obese range) and not among participants whose BMI was less than 25 (normal or underweight).


Biomarkers of insulin resistance seemed to be the biggest contributor to lower risk, followed by biomarkers of body mass index, high-density lipoprotein measures, and inflammation. Although much of the benefit can be explained through just a few pathways and it is important to note that many of these changes do not happen right away, while metabolism can change over a short period, the study indicates that there are longer term changes happening that may occur over decades. The findings support the idea that by improving their diet, people can improve their future risk of type 2 diabetes, particularly if they are overweight or have obesity.


Source: Ahmad F, Demler OV, Sun Q, et al. Association of the Mediterranean diet with onset of diabetes in the Women's Health Study. JAMA Netw Open. 2020;3:e2025466. doi: 10.1001/jamanetworkopen.2020.25466



Personalized nutrition (PN) behavior-change interventions are being used increasingly in attempts to improve dietary intake; however, the impact of PN advice on improvements in dietary intake has not been reviewed systematically. The aim of this systematic review was to evaluate the effect of PN advice on changes in dietary intake compared with generalized advice in healthy adults. Three databases (EMBASE, PubMed, and CINAHL) were searched between 2009 and 2020 for randomized controlled trials that tested the effect of PN and tailored advice based on diet, phenotype, or genetic information. The Evidence Analysis Library Quality Criteria checklist from the Academy of Nutrition and Dietetics was used to conduct a risk-of-bias assessment. Information on intervention design and changes in nutrients, foods, and dietary patterns was extracted from the 11 studies meeting the inclusion criteria. Studies were conducted in the United States, Canada, or Europe; reported outcomes on 57 to 1488 participants; and varied in follow-up duration from 1 to 12 months. Five studies incorporated behavior-change techniques. The risk of bias for the included studies was low. Overall, the available evidence suggests that dietary intake is improved to a greater extent in participants randomly assigned to receive PN advice compared with generalized dietary advice. Additional studies that incorporate behavior-change techniques, a broader range of dietary outcomes, and comparisons between personalization based on dietary, biological, and/or lifestyle information are needed to provide a more in-depth understanding of ways to tailor nutrition information to individuals.


Source: Jinnette R, Narita A, Manning B, et al. Does personalized nutrition advice improve dietary intake in healthy adults? A systematic review of randomized controlled trials. Adv Nutr. 2020; nmaa144.



About one-half of US adults have diet-related chronic diseases, such as cardiovascular disease, high blood pressure, or type 2 diabetes. Special diets are one way that many adults prevent, treat, and manage such diseases. A new report shows the percentage of US adults who, on a given day, were on any special diet and the specific types of special diets in 2015 to 2018 and trends from 2007-2008 through 2017-2018. Approximately 17% of adults 20 years or older reported being on any type of special diet in 2015 to 2018, with more women (19%) than men (15%) reporting being on a special diet. Among all adults, the percentage of younger adults aged 20 to 39 years reporting being on a special diet (13%) was lower compared with those aged 40 to 59 years (19%) and those 60 years or older (19%). The percentage of adults on a special diet was higher among non-Hispanic White adults (18%) than non-Hispanic Black (15%) and non-Hispanic Asian (15%) adults. The percentage of Hispanics on a special diet (16%) was not significantly different compared with the other race and Hispanic-origin groups. The percentage of adults on a special diet increased with increasing weight status (8% for normal or underweight, 17% for overweight, and 23% for obese persons) and increasing educational level (14% for less than high school education, 17% for high school education or some college, and 19% for college graduate or higher). The top 4 most common types of special diets reported by adults were weight loss or low-calorie diets (used by 9%), diabetic diets (2%), low-carbohydrate diets (2%), and low-fat or low-cholesterol diets (2%). The most common type of special diet among every age group was a weight loss or low-calorie diet. From 2007-2008 through 2017-2018, the percentage of adults on any special diet, weight loss or low-calorie diets, and low-carbohydrate diets increased, whereas the percentage of those on low-fat or low- cholesterol diets decreased.


Source: Stierman B, Ansai N, Mishra S, Hales CM. Special Diets Among Adults: United States, 2015-2018. NCHS Data Brief No. 389. Hyattsville, MD: National Center for Health Statistics; 2020.



A new study has discovered that vitamin D regulates calcium in a section of the intestine that previously was thought not to have played a key role. The findings have important implications on how bowel disease, including ulcerative colitis and Crohn's disease, may disrupt calcium regulation. In a healthy person, the body absorbs calcium to maintain strong bones and perform other important functions like helping muscles move and nerves carry messages between the brain and body parts. Vitamin D is critical for this calcium absorption from the intestine and for the function of the intestine. The study highlights the importance of the distal segments of the intestine-including the colon-in vitamin D regulation of calcium and bone calcification. Previously, this regulation was thought to occur only in the proximal intestine, the first section of the intestine immediately beyond the stomach. From the study, researchers also learned that a transporter of manganese-an essential element that plays a role in many cellular processes-was one of the genes most induced by vitamin D in both the proximal and distal intestine. The researchers say that these findings suggest that vitamin D may have a role not only in calcium absorption but also in the cellular regulation of other essential ions and in the function of intestinal stem cells. This research may also lead to new strategies that can compensate for calcium malabsorption and increase the efficacy of intestinal calcium uptake to minimize bone loss due to bariatric surgery, small bowel resection, or reduced calcium absorption after menopause or due to aging.


Source: Shanshan Li, Jessica De La Cruz, Steven Hutchens, et al. Analysis of 1,25-dihydroxyvitamin D3 genomic action reveals calcium regulating and calcium independent effects in mouse intestine and human enteroids. Molecular and Cellular Biology. 2020; DOI: 10.1128/MCB.00372-20.