Whole grains

The standard American diet is infamous for its high levels of refined carbs, sugar, and saturated fats. To see if nutrition initiatives are taking hold, researchers analyzed the diets of 43,996 U.S. adults in 1999 and then again in 2016. Over this time period, people got 1.23% more calories from high quality carbs (whole grains), 0.38% more calories from plant protein, 0.65% more calories from polyunsaturated fats, and 3.25% fewer calories from low quality carbohydrates (sugar and refined grains). Unfortunately, calories from saturated fat increased by 0.36%, and the general diet is still far from ideal, with 42% of calories still coming from low quality carbs, and saturated fat remaining above 10% of energy intake.
JAMA. 2019 Sep 24;322(12):1178-1187. doi: 10.1001/jama.2019.13771.(Shan Z et al.)

Researchers randomly assigned 148 overweight and obese adults to a low-fat vegan diet, or to continue their usual diet for 16 weeks. Those in the vegan group lost about a pound per week, and also lost a significant amount of body fat. Additionally, the vegan group (who ate lots of legumes, fruits, vegetables, and nuts) also had higher levels of beneficial bacteriodetes in their gut. This may partially explain some of the health benefits of plant-based diets, because people with diabetes, insulin resistance, and inflammation tend to have low levels of bacteriodetes. (Note that findings presented at meetings are considered preliminary until published in a peer-reviewed journal.)
Presentation at European Association for the Study of Diabetes 2019 Annual Meeting. Barcelona, Spain. September 17, 2019.

In this study, researchers asked 169 low-income adults to look at 11 foods in their original packaging and determine if each was a whole grain or a refined grain. The majority of participants (7 out of 10) correctly identified 4 out of 5 of the whole grain products as whole grain, and nearly as many (6 out of 10) participants correctly identified 5 out of the 6 refined grain products. Specifically, 9/10 people correctly identified whole grain bread, 8/10 correctly identified whole grain crackers & whole grain cereal, and 7/10 correctly identified oatmeal as a whole grain, while popcorn tripped most people up (with only 3/10 people correctly identifying it as a whole grain food). Similarly, 8/10 correctly identified refined crackers, 7/10 correctly identified refined macaroni and tortillas, and 6/10 correctly identified refined bread and cereal, while white rice was tricky for people (with only 4/10 correctly identifying it as a refined grain). Based on interviews with a subset of 60 of the participants, the researchers found that helping people more clearly identify whole grains on the package, and reducing the cost (or perceived cost) of whole grain foods may help increase whole grain consumption in low-income adults.
Current Developments in Nutrition. 2019 May 16;3(7):nzz064. doi: 10.1093/cdn/nzz064. (Chea M et al.)

Paleo diets tend to be high in meat and vegetables, while restricting all grains and dairy products. In this study, researchers analyzed the microbiome of 44 people who had been following a Paleo diet for at least 1 year, and 47 people who eat a healthy diet reflective of dietary guidelines. Those strictly following a Paleo Diet and those eating a standard healthy diet ate significantly more fiber than those only loosely following a Paleo diet. However, those who strictly followed the Paleo diet (eating the lowest levels of whole grains and total grains) were significantly more likely to have higher levels of TMAO (a compound generated by the gut microbiome that is associated with plaque buildup in the arteries). The authors also added that “the rationale to exclude whole grains is not supported by data presented here; being inversely associated with body weight and TMAO concentrations.”
European Journal of Nutrition. 2019 Jul 5. doi: 10.1007/s00394-019-02036-y. [Epub ahead of print] (Genoni A et al.)

Numerous studies have been published on diet and diabetes risk, but the quality of these studies varies widely, making it hard to compare the risks and benefits of different food choices. In this analysis, researchers reviewed 53 studies on diet and type 2 diabetes risk, and evaluated their strength and validity. There was high evidence that 30g per day of whole grains was linked with a 13% lower risk of developing type 2 diabetes and that 10g per day of fiber from grains was linked with a 25% lower risk of developing type 2 diabetes. There was also moderate evidence that 0.5-1 ounce of alcohol per day was linked with a 25% lower risk of type 2 diabetes than not drinking at all. On the other hand, eating 3.5 ounces of red meat daily, 2 ounces of processed meat daily, 2 slices of bacon daily, or one serving of sugar sweetened beverages were all strongly linked with a higher risk of type 2 diabetes.
BMJ. 2019 Jul 3;366:l2368. doi: 10.1136/bmj.l2368. (Neuenschwander M et al.)

Hepatocellular carcinoma is the most common form of liver cancer. In this study of 125,455 adults in the U.S., eating more whole grains was linked with a significantly lower risk of developing hepatocellular carcinoma over the 24-year study period. The results were statistically significant for whole grains overall and were not statistically significant when looking at bran intake, germ intake, or fiber from whole grains, thus indicating that the whole grain is greater than the sum of its parts.
JAMA Oncology. 2019 Jun 1;5(6):879-886. doi: 10.1001/jamaoncol.2018.7159. (Yang Y et al.)

Longevity is fascinating to study, but what is perhaps more important than the years in your life is the life in your years – the ability to age successfully from a medical, social, and lifestyle point of view. In this study, researchers evaluated whole grain intake and measured “successful aging” (using social, lifestyle, and medical indicators) in a group of 3,349 adults ages 50+. Those eating the most whole grains (about 7 servings per day) were significantly more likely to score higher on the “successful aging index” than those eating the least whole grains (about 1.5 servings per day). Those eating the most whole grains were also less likely to have high blood pressure, diabetes, and high cholesterol.
Nutrients. 2019 May 29;11(6). pii: E1221. doi: 10.3390/nu11061221. (Foscolou A et al.)

Eating a healthy diet can help protect our health from a number of conditions and complications, so researchers wonder how diet might relate to cancer risk. In this study, researchers used models and dietary data to analyze the cancer cases from 2015. They found that 5.2% of all new cancer cases in 2015 could be attributed to poor diet, with 1.8% attributable to low whole grain consumption, 1.2% attributable to low dairy consumption, and 1% attributable to processed meats. The link with colorectal cancer shows the strongest relationship with diet, as poor diet is linked with 38.3% of all new colorectal cancer cases.
JNCI Cancer Spectrum. 2019 May 22;3(2):pkz034. doi: 10.1093/jncics/pkz034. (Zhang FF et al.)

Insulin is a hormone that helps your body manage your blood sugar, by keeping it from getting too high or too low. In this study, 13 adults with “pre-diabetes” were given a diet with either whole grains or refined grains for 8 weeks, then given a glucose test to assess how well their blood sugar was being managed. They then had a washout period of their normal diet for 8-10 weeks, before switching to the other diet for 8 weeks and taking the glucose test again, thus serving as their own controls. The whole grain diet improved the function of beta cells (the cells that secrete insulin) compared with the refined grain diet, and this effect was found to be independent of gut hormones (such as grehlin, the “hunger hormone”).
Molecular Nutrition and Food Research. 2019 Apr;63(7):e1800967. doi: 10.1002/mnfr.201800967. (Malin SK et al.)

Hepatocellular carcinoma, a common type of liver cancer, has been on the rise in the US, and researchers wonder if eating habits might play a role. In a study of 125,455 adults followed for 24 years, those eating the most whole grains (33g per day, or about 2 servings) were 37% less likely to develop hepatocellular carcinoma than those eating the least whole grains (7g per day, or less than half a serving). When looking at the isolated relationship of fiber, bran, and germ, the results were not statistically significant, indicating that whole grains are greater than the sum of their parts.
JAMA Oncology. 2019 Feb 21. doi: 10.1001/jamaoncol.2018.7159. [Epub ahead of print] (Yang W et al.)