Past Week in Nutrition Science (April 15th–22nd)

This is an overview of interesting nutrition research published from Friday, April 15th, to Friday, April 22nd, 2016.

Woman Holding Two Pomegranites

Research Reviews

This week, we reviewed two articles: one on the effects of A2 milk on digestive symptoms and another examining the effects of linoleic acid on heart disease risk.

Review: A2 Milk May Be Safe for Milk-Intolerant People.

Article: Effects of milk containing only A2 beta casein versus milk containing both A1 and A2 beta casein proteins on gastrointestinal physiology, symptoms of discomfort, and cognitive behavior of people with self-reported intolerance to traditional cow’s milk.

Summary: This randomized controlled trial compared the effects of A2 milk and conventional milk on digestive symptoms, inflammation and mental performance in Chinese adults with self-reported lactose intolerance.

The study showed that while conventional milk causes adverse symptoms for those sensitive to milk, A2 milk appeared to have no adverse effects. However, further studies need to confirm these findings.

Review: Too Much Linoleic Acid May Increase Heart Disease Risk.

Article: Re-evaluation of the traditional diet-heart hypothesis: analysis of recovered data from Minnesota Coronary Experiment (1968–73).

Summary: This study analyzed unpublished data from a large randomized controlled trial examining the effects of high linoleic acid intake on cholesterol levels and heart disease. The trial was conducted in the late ’60s and early ’70s.

The main findings were that replacing saturated fat with linoleic acid has no benefits for heart health. While it does lower cholesterol, it may still increase the risk of heart disease and death.

New Research From Around the World

A number of new papers came to our attention this week. Here are summaries of the most interesting or relevant studies, categorized by subject.

1. Obesity and Weight Loss

Prebiotics as a modulator of gut microbiota in paediatric obesity.

Prebiotics are a group of fiber that can change the composition of the gut microbiota and stimulate the growth of beneficial gut bacteria. Studies indicate that supplementing with prebiotics may help prevent obesity and chronic disease.

This review discusses the role of the gut microbiota in childhood obesity, and the possible benefits of supplementing with prebiotics.

Associations between meal and snack frequency and overweight and abdominal obesity in US children and adolescents from National Health and Nutrition Examination Survey (NHANES) 2003–2012.

This observational study in children indicates that higher eating and snacking frequency may increase the risk of weight gain and obesity. However, meal frequency was not significantly associated with either.

2. Metabolic Syndrome

Association between the dietary inflammatory index, waist-to-hip ratio and metabolic syndrome.

The Dietary Inflammatory Index (DII) rates the inflammatory potential of a diet. Some foods are pro-inflammatory, whereas others are anti-inflammatory or neutral.

This observational study suggests that eating foods that promote inflammation, as measured using the DII, does not increase people’s risk of metabolic disease.

3. Heart Health

Prospective Association Between the Dietary Inflammatory Index and Cardiovascular Diseases in the Supplementation en Vitamines et Mineraux AntioXydants (SU.VI.MAX) Cohort.

This observational study linked foods that promote inflammation, as measured by the Dietary Inflammatory Index, to a higher risk of heart attack.

Middle-Term Dietary Supplementation with Red Yeast Rice Plus Coenzyme Q10 Improves Lipid Pattern, Endothelial Reactivity and Arterial Stiffness in Moderately Hypercholesterolemic Subjects.

This randomized controlled trial in 40 adults with elevated cholesterol levels examined the health benefits of a dietary supplement containing 30 g of coenzyme Q10 and 10 g of monacolins — compounds found in red yeast rice.

The study showed that taking this supplement daily for 6 months reduced LDL-cholesterol by 26% and arterial stiffness by 5%.

4. Cancer

Dietary mineral intake and lung cancer risk: the Rotterdam Study.

This observational study suggests that dietary zinc and iron may reduce the risk of lung cancer. Conversely, dietary calcium, copper, magnesium and selenium were not significantly associated with lung cancer risk.

Dietary pattern and breast cancer risk in Japanese women: the Japan Public Health Center-based Prospective Study (JPHC Study).

This observational study in Japanese women found that a Western dietary pattern was associated with an increased risk of breast cancer. In contrast, a prudent diet and a traditional Japanese diet were not linked with breast cancer risk.

Vegetarian dietary patterns and the risk of breast cancer in a low-risk population.

This observational study in American women suggests that a vegetarian diet does not decrease the risk of breast cancer, compared to non-vegetarians. However, vegans may be at a lower risk.

5. Appetite and Eating

Differing effects of high-fat or high-carbohydrate meals on food hedonics in overweight and obese individuals.

This study in overweight and obese individuals showed that they liked eating a low-fat, high-carb meal (LFHC) better than a high-fat, low-carb meal (HFLC). Calorie intake was higher during the LFHC meal, and fullness was higher afterward.

6. Brain and Mental Health

Association between serum long-chain omega-3 polyunsaturated fatty acids (PUFAs) and cognitive performance in elderly men and women: The Kuopio Ischaemic Heart Disease Risk Factor Study.

This observational study found that higher levels of circulating omega-3 polyunsaturated fatty acids — EPA, DPA and DHA — were linked to better mental performance in elderly people.

Plasma Carotenoids Are Inversely Associated With Dementia Risk in an Elderly French Cohort.

Lutein is an antioxidant found in high amounts in many vegetables, such as kale, spinach, turnip greens, watercress, romaine lettuce, zucchini and Brussels sprouts.

This observational study in elderly people showed that high circulating levels of lutein were linked with a reduced risk of dementia.

Stunting, selenium deficiency and anemia are associated with poor cognitive performance in preschool children from rural Ethiopia.

This observational study in children from rural Ethiopia found that low levels of iron and selenium were linked with poor mental performance.

Food patterns and the prevention of depression.

This review discusses the evidence linking food patterns with mental depression. Studies indicate that diets characterized by lots of seafood, vegetables, fruits and nuts may potentially reduce the risk of depression.

Long-term association between the dietary inflammatory index and cognitive functioning: findings from the SU.VI.MAX study.

This observational study suggests that eating foods that promote inflammation, as measured by the Dietary Inflammatory Index, may impair mental performance.

7. Digestive Health

Psyllium Fiber Reduces Abdominal Pain in Children with Irritable Bowel Syndrome in a Randomized, Double-blind Trial.

Psyllium husk is a type of fiber made from the seed covering of psyllium plants.

This randomized controlled trial in children with irritable bowel syndrome (IBS) showed that supplementing with psyllium husk for 6 weeks reduced the number of abdominal pain episodes.

8. Allergies and Autoimmune Disorders

Soy isoflavone intake is associated with risk of Kawasaki disease.

Kawasaki disease is a rare autoimmune condition, most often seen in Asian children under 5 years of age. It causes inflammation throughout the body, affecting blood vessels, lymph nodes and skin.

This observational study showed that the dietary exposure of soy isoflavones is associated with an increased risk of Kawasaki disease in US children.

9. Infections and Immune Health

Does larch arabinogalactan enhance immune function? A review of mechanistic and clinical trials.

Arabinogalactan is a fermentable fiber found in various plants. Supplemental arabinogalactan is isolated from larch trees, and is known as larch arabinogalactan.

This review discusses the potential of larch arabinogalactan for improving immune function. The authors conclude that arabinogalactan may help fight the common cold, but how this works is unknown.

10. Pregnancy and Infant Health

Omega-3 LCPUFA supplement: a nutritional strategy to prevent maternal and neonatal oxidative stress.

Long-chain, omega-3 polyunsaturated fatty acids, such as EPA and DHA, are found in fish oil. They are generally considered healthy, but some scientists are concerned they may increase oxidative stress in the body.

This randomized controlled trial in pregnant mothers showed that supplementing with omega-3 from fish oil (400 mg EPA and DHA daily) decreased markers of oxidative stress and increased levels of antioxidants in both the mother and child.

11. Longevity and Healthy Aging

Influence of diet on leukocyte telomere length, markers of inflammation and oxidative stress in individuals with varied glucose tolerance: a Chinese population study.

Telomeres are sequences of DNA at the ends of DNA strands, protecting them from fusing with neighboring strands. They naturally shorten with age, but oxidative stress may accelerate their shortening, possibly contributing to aging.

This observational study in Chinese adults suggests that elevated blood sugar levels may speed up telomere shortening. Conversely, eating legumes, nuts, fish and seaweed may protect the telomeres.

Nutrition and physical activity for the prevention and treatment of age-related sarcopenia.

Sarcopenia describes the loss of muscle mass that occurs with age. It’s a common cause of poor health, frailty and impaired quality of life among the elderly.

This review discusses the most important dietary considerations in the prevention of sarcopenia: adequate amounts of protein, frequency of protein consumption, sufficient protein quality and strength exercises.