SEARCH HEALTH STUDIES

Whole Grains May Help Your Body Burn More Calories

Whole grains are often associated with lower body weights, and new research is uncovering why. In a randomized trial, scientists assigned 81 healthy adults in Boston to diets with either whole grains or refined grains for 6 weeks, keeping all other foods and nutrients consistent between the groups. Although the diets were designed to be isocaloric (meaning that people were supposed to maintain their same body weight), the resting metabolic rate (how many calories your body burns at rest) became significantly higher (by 43 calories) in the whole grain group. In fact, the whole grain group significantly improved their metabolism over the 6-week study compared with the refined grains group, burning 92 more calories per day. The researchers suspect that this is partly due to the fact that the whole grain group excreted more energy in the stool, and had more frequent bowel movements.
American Journal of Clinical Nutrition. 2017 Feb 8. pii: ajcn139683. [Epub ahead of print.] (Karl JP et al.)

Whole Grains Can Improve Gut Microbiota

Researchers randomly assigned 81 healthy adults in Boston to diets with either whole grains or refined grains for 6 weeks, keeping all other foods and nutrients consistent between the groups. The researchers found that making all of your grains whole is linked with “modest, positive effects on gut micriobiota,” (due to higher concentrations of “good” gut microbes and short chain fatty acids – an indicator of colon health and dietary fiber breakdown) as well as increased stool weight and stool frequency.
American Journal of Clinical Nutrition. 2017 Feb 8. pii: ajcn146928. [Epub ahead of print.] (Vanegas SM et al.)

Whole Grains & Fiber Linked with Less Colorectal Cancer

Because colorectal cancer forms in the large intestine, diet is thought to be a potential risk factor. To see how food fits into the puzzle, scientists at Harvard analyzed the eating patterns and health markers of 137,217 adults for more than two decades. Those eating a healthy diet rich in fiber and whole grains were significantly less likely to develop a certain type of colorectal cancer (Fusobacterium nucleatum–positive, but not Fusobacterium nucleatum-negative) than those eating a “Western diet” rich in red meat, refined grains, and dessert. Fusobacterium nucleatum is a type of gut bacteria thought to contribute to colorectal cancer, as it’s often elevated in colorectal cancer patients. Based on their findings, the scientists suspect that the cancer-protective effect of fiber and whole grains may have to do with their role in improving the gut microbiome.
JAMA Oncology.  2017 Jan 26. [Epub ahead of print.] (Mehta RS)

Plant Foods Important to Original Paleo Diet

Archeologists analyzed the preserved plant remains at an Acheulian site in Israel to determine the role of plant foods (if any) in ancient diets. Contrary to the popular, meat-centric interpretation of a paleo diet, the researchers argue that “a wide spectrum of food plants was a permanent aspect of the pre-agricultural hominin economy,” and that the abundance of fruit, nut, seed, and grain plants “is a result of deliberate hominid behavior.” The researchers also found “ample evidence for the important role of fire at GBY [Gesher Benot Ya’aqov], with its control and repeated uses shown by burned lithics and charred wood, bark, grains, and fruits. The plant remains, dating back about 780,000 years, led researchers to conclude that “our results change previous notions of paleo diet.”
Proceedings of the National Academy of Sciences of the United States of America. 2016 Dec 20;113(51):14674-14679. (Melamed Y et al.)

Replacing Animal Fats with Whole Grains, Polyunsaturated Fats, or Plant Proteins Linked with Less Heart Disease

Fat is essential to the diet, but certain fats are better than others. Scientists analyzed the eating patterns and health outcomes of more than 115,000 men and women in the Nurse’s Health Study and the Health Professionals Follow Up Study. The scientists found that those eating the most saturated fats (the types of fats found in red meat, butter, and milk) were more likely to get heart disease over the 24-28 year study period. In fact, replacing just 1% of calories from saturated fat with the same amount of calories from whole grains, polyunsaturated fats (found in fish, nuts, and seeds), or plant proteins (such as beans or nuts) is linked with a 6-8% lower risk of heart disease. The scientists conclude that “dietary recommendations for the prevention of coronary heart disease should continue to focus on replacing total saturated fat with more healthy sources of energy.”
British Medical Journal. 2016 Nov; 355:i5796. (G Zong et al.)

Switching to Whole Grains Improves Blood Pressure

In a small study, researchers assigned overweight and obese adults in Ohio to one of two diets for 8 weeks, one with whole grains, one with refined grains. After going back to their normal diet for 10 weeks as a washout, the 33 participants then switched diets, serving as their own control. Both diet groups lost weight and body fat, and lowered their systolic blood pressure (the top number in a blood pressure reading), total cholesterol, and LDL (“bad”) cholesterol. The scientists also found that the whole grain diet reduced diastolic blood pressure (the bottom number in the blood pressure reading) by 5.8 mm Hg, “or an additional 4.2 mm Hg beyond any change attributable to weight loss.” According to the researchers, this improvement, which was 3-fold greater in the whole grain group than the refined grain group, “approximates to a 40% lower risk of dying from stroke and a 30% lower risk of dying from ischemic heart disease or other vascular causes.”  
The Journal of Nutrition. 2016 Oct 19. pii: jn230508. [Epub ahead of print] (Kirwan JP et al.)

Whole Grains, Pasta Linked with Lower Breast Cancer Risk

An estimated 1 in 8 women in the US will develop invasive breast cancer over her lifetime, so preventive lifestyle choices are an important area of research. To see how diet plays a role, Harvard scientists analyzed the grain food choices of 90,516 pre-menopausal women, and monitored their health outcomes for 22 years. After adjusting for known breast cancer risk factors, those eating 1.5 servings of whole grains per day were 18% less likely to get pre-menopausal breast cancer than those eating hardly any whole grains (0.2 servings/day). This relationship was no longer significant after adjusting for fiber, suggesting that the fiber in whole grains may play a protective role. When looking at individual grain foods, brown rice and pasta (white or whole grain) were associated with a lower risk of overall breast cancer risk, while white bread was linked with a higher risk of overall breast cancer.
Breast Cancer Research and Treatment. 2016 Sep;159(2):335-45. (Farvid MS et al.)

Fruits, Vegetables, Legumes, Whole Grains Linked with Less Pre-Diabetes

Pre-diabetes can increase the risk of diabetes and heart disease, so understanding lifestyle factors is important. To see how diet relates to pre-diabetes, scientists analyzed the eating habits of 150 pre-diabetic adults in Iran, and 150 healthy, matched controls. Two distinct eating patterns emerged: the “vegetable, fruit, legume” pattern, with lots of plant foods including produce, whole grains, nuts, low fat dairy, and fish, and the “sweet, solid fat, meat, and mayonnaise” pattern, with lots desserts, red meat, fried potatoes, and solid fats. Those whose diets more aligned with the “vegetable, fruit, legume” pattern were significantly less likely to be pre-diabetic than those whose diets more closely resembled the “sweet, solid fat, meat, and mayonnaise” pattern.
British Journal of Nutrition. 2016 Sep;116(5):874-81. (Bagheri F et al.)

Healthy Diet Linked with Better Reading Skills in Children

To help set your kids up for academic success, don’t overlook the importance of a healthy diet. Scientists analyzed the eating habits of 161 Finnish children in first grade, then monitored their academic performance in grades 1-3. Kids with healthier diets that emphasized fruits, vegetables, whole grains, fish, nuts, and low fat dairy, had better reading fluency and reading comprehension than those whose diets ranked more poorly. There were no statistically significant differences in math performance related to diet.
European Journal of Nutrition. 2016 Sep 9. [Epub ahead of print] (Haapala EA et al.)

Whole Grains & Polyunsaturated Fats Linked with Less Heart Disease

To see how various fat sources relate to heart disease, Harvard researchers analyzed the fat intake and health outcomes of more than 222,000 people across 3 large cohorts. They found that while dairy fat intake in itself was not significantly related to heart disease risk, replacing 5% of calories from dairy fat with whole grains, polyunsaturated fat (found in fish, nuts, and seeds) or vegetable fat was linked with a 28%, 24% and 10% lower risk of heart disease, respectively. Additionally, replacing 5% of calories from other animal fats (such as red meat) with dairy fat was linked with a 6% lower risk of heart disease, indicating that while dairy fat might not be as harmful as red meat, replacing animal fats with plant foods could offer more protection. This supports the evidence that we consume and what we don’t consume both contribute to health outcomes. 
American Journal of Clinical Nutrition. 2016 Aug 24. pii: ajcn134460. [Epub ahead of print] (Chen M et al.)

Whole Grains Linked with Longevity

In a meta analysis, Harvard scientists analyzed the whole grain intake and rates of death for 786,076 adults across 14 studies. Compared to people who ate the least whole grains, people who ate the most whole grains had a 16% lower risk of death from all causes, an 18% lower risk of death from heart disease, and a 12% lower risk of death from cancer. However, the significantly lower risk of cancer death was only seen in people who ate at least 30g whole grains per day (the amount in about ½ cup cooked brown rice, or 2 slices of 100% whole grain bread). The researchers also observed a dose response relationship, meaning the more whole grains someone ate, the less likely they were to die during the study period. According to the scientists, these results “strongly supported the current Dietary Guidelines for Americans,” which encourage at least 3 servings of whole grains per day (totaling at least 48g whole grains).
Circulation. 2016 Jun 14;133(24):2370-80. (Zong G et al.)

Whole Grains Linked with Lower Risk of Heart Disease, Cancer, Respiratory Disease, Infectious Diseases, Diabetes, and Early Death

Researchers in Europe and the US analyzed 45 studies (ranging from 245,012 to 705,253 participants each) in a meta analysis to understand the relationship between whole grains and health. Compared to people who ate the least whole grains, people who ate the most whole grains had a 16-21% lower risk of heart disease, an 11% lower risk of cancer, and an 18% lower risk of death from all causes, as well as a 19% lower risk of death from respiratory disease, a 36% lower risk of death from diabetes, a 20% lower risk of death from infectious disease, and a 21% lower risk of death from all non-cardiovascular, non-cancer causes. The researchers also found that a 90g increase in whole grain foods per day (about 3 servings) was linked with a 19-22% lower risk of heart disease, a 15% lower risk of cancer, and a 17% lower risk of death from all causes, and that “even moderate increases in whole grain intake could reduce the risk of premature mortality.” Whole grain bread, whole grain cereals, total grains, total cereals, total bread, pasta, and bran, were also singled out for their relationship with lower rates of various diseases and/or early death. The researchers conclude that their findings “strongly support existing dietary recommendations to increase whole grain consumption in the general population.”
British Medical Journal. 2016 June 14;353. (Aune D et al.)

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