[black small square] Dietary Impact on Land Use in the United States
[black small square] The Genetics of Diabetes
[black small square] Diabetic Kidney Disease
US LAND CAPACITY FOR FEEDING PEOPLE COULD EXPAND WITH DIETARY CHANGES
A new "food-print" model that measures the per-person land requirements of different diets suggests that, with dietary changes, the United States could feed significantly more people from the existing agricultural land. Using 10 different scenarios ranging from the average American diet to a purely vegan one, the scientists estimated that agricultural land in the contiguous United States could have the capacity to feed up to 800 million people-twice what can be supported based on current average diets. In an article published in an open access journal this summer, the researchers found that a vegetarian diet that includes dairy products could feed the most people from the area of land available.
They chose 10 dietary scenarios that were comparable nutritionally but varied by the sources of protein. Eight of the diets complied with the 2010 Dietary Guidelines for Americans. A baseline diet represented the country's current food consumption-higher in meats, grains, fats, and sweeteners than the other dietary scenarios. In this baseline diet, roughly 80% of the available cropland was used to grow crops for animal feed, such as hay, whereas the other 20% was devoted to fruits, vegetables, and grains for human consumption.
The remaining dietary scenarios ranged from 100% of the population eating a healthy omnivorous diet (a balance of meat and plant-based foods) to 100% of the population eating a vegan diet (which excludes meat and all other animal by-products such as milk, eggs, and honey). Intermediate scenarios included varying proportions of omnivores and vegetarians, and the accompanying cropland use varied.
To develop the model, the team began with an estimate of hypothetical food intake by food group. These are critical assumptions in any modeling exercise; it is not entirely clear how the authors accounted for the acceptability, and cost of the various patterns that were generated was measured. Those assumptions deserve careful assessment in additional peer-reviewed studies. Once the researchers had data on hypothetical food intake by food group, they then worked backward to calculate the food quantity that must be produced, the agricultural raw material needed to produce those foods, the total land requirements, and the number of people who can be fed from the land used to produce those foods. The model accounts for factors such as the suitability of cropland for cultivation, the interdependencies of dairy and meat production, and the use of co-products of food production to feed livestock. As the amount of meat in the diet was reduced between scenarios, it followed that the amount of land necessary for crops to feed livestock was also reduced. As expected, the baseline diet had the lowest carrying capacity and required 8 times more land than a vegan diet accordingly. The research team found using their models that:
* A lacto-vegetarian diet (a vegetarian diet that includes dairy products) had the highest carrying capacity, meaning that it could feed the most people from the area of land available.
* Surprisingly, diets including some meat could feed more people than vegan diets, depending on estimates of how much land was suitable for crop cultivation.
* The overall results from the model estimated that US agricultural land had the capacity to meet the needs of a population 1.3 to 2.6 times larger than the US population in 2010.
The researchers caution that, before "we go about converting land to other uses, to develop sound agricultural policy, we have to understand the impact of dietary patterns on land use. We don't want to shortchange the equitable distribution of nutritious, life-sustaining foods to the whole population."
Source: Peters C, Picardy J, Darrouzet-Nardi AF, Wilkins JL, Griffin TS, Fick GW. Carrying capacity of U.S. agricultural land: a comparison of ten human diet scenarios. Elementa. 4:000116. doi:10.12952/journal.elementa.000116
GENETICS OF TYPE 2 DIABETES REVEALED IN UNPRECEDENTED DETAIL
The largest study of its kind into type 2 diabetes has produced the most detailed picture to date of the genetics underlying the condition. More than 300 scientists from 22 countries collaborated on the study, which analyzed the genomes of more than 120 000 people with ancestral origins in Europe, South and East Asia, the Americas, and Africa.
Type 2 diabetes is a growing threat to global health, with 1 in 10 people either having the disease or predicted to develop it during their lifetime. For any given individual, the risk of developing this form of diabetes is influenced by the pattern of genetic changes inherited from their parents and environmental factors such as levels of exercise and choice of diet.
Previous studies have identified more than 80 areas in the genome that are associated with type 2 diabetes. However, these studies focused on the role of common DNA differences that appear frequently in the population, and they generally stopped short of identifying exactly which DNA sequence changes, or which specific genes, were responsible for this risk.
The study explored the impact of changes in the DNA sequence on diabetes risk at a more detailed level. Some individuals had their entire genome sequenced, whereas, for others, sequencing was restricted to the part of the genome that codes directly for proteins (the exome). Scientists then compared the genetic variation between individuals who had type 2 diabetes and those who did not. This allowed them to test the contribution made by rare, "private" DNA differences that were unique, as well as those that are common and shared between people. They found that most of the genetic risk of type 2 diabetes can be attributed to common, shared differences in the genetic code, each of which contributes a small amount to an individual's risk of disease. Some researchers had thought that genetic risk would instead be dominated by rare changes, unique to an individual and his/her relatives. Researchers also identified more than a dozen of type 2 diabetes risk genes where the DNA sequence changes altered the composition of the proteins they encode, implicating those specific genes and proteins directly in the development of type 2 diabetes.
One such variant-in the TM6SF2 gene-has been shown to alter the amount of fat stored in the liver, which in turn results in an increase in the risk of type 2 diabetes. Discoveries such as these point to new opportunities for developing drugs that might interrupt the development of the disease.
Data and discoveries generated through this project are available through the type 2 diabetes genetics portal (http://www.type2diabetesgenetics.org) developed as part of the Accelerating Medicines Partnership.
The researchers concluded that the large range of genetic effects may challenge efforts to deliver personalized medicine. Nevertheless, they hope that the data from the study publicly made accessible for researchers around the world will accelerate efforts to understand, prevent, and treat this condition.
Source: Fuchsberger C, Flannick J, Teslovich TM, et al. The genetic architecture of type 2 diabetes. Nature. 2016;536:41-47. doi:10.1038/nature18642
REPLACING ONLY 1 SUGARY DRINK WITH WATER COULD SIGNIFICANTLY IMPROVE HEALTH, VIRGINIA TECH RESEARCHER FINDS
Think 1 little sugary soda won't make a difference on your waistline? Think again.
According to new research, if people replaced only 1 calorie-laden drink with water, they might be able to reduce body weight and improve overall health. The researchers found that, regardless of how many servings of sugar-sweetened beverages are consumed, replacing even only 1 serving could be of benefit. There is a fly in the ointment, however; it seems that the researchers assumed that the phenomenon of caloric compensation would not occur, that is, the propensity for people to substitute something else for that they have cut out, so that they often end up eating as much as they did to begin with. The authors modeled the effect of replacing one 8-oz sugar-sweetened beverage with an 8-oz serving of water, based on the daily dietary intake of US adults aged 19 and older, retrieved from the 2007 to 2012 National Health and Nutrition Examination Surveys. The researchers showed that this one-for-one drink swap could reduce daily calories and the prevalence of obesity in populations that consume sugary beverages. Of course, the same effect would also be observed with drinkers and nondrinkers of calorie-laden alcoholic drinks; the question is how much compensations would or would not take place? The 2015 Dietary Guidelines for Americans recommend that no more than 10% of daily calories come from added sugar and that calorie-free drinks, particularly water, should be favored. It remains to be seen whether these measures will reduce weight and fatness in actuality. An interesting review in the new publication "Frontiers in Nutrition" by Simon Thornton in France suggests that increased hydration can be associated with weight loss. Although most of the studies are in experimental animals, there are some suggestive data in humans as well. Now, better studies in humans are needed to confirm the hypothesis.
Source: Nutrients. 2016;8(7):pii:E395. doi:10.3390/nu8070395
Frontiers in Nutrition. 2016;3:18.