This is an overview of interesting nutrition research published from Friday, April 8th, to Friday, April 15th, 2016.
This week, we reviewed one article on salt intake and weight gain, and another examining the effects of alternate-day fasting on appetite.
Summary: This was a randomized, crossover trial examining the effects of salt and fat on food and calorie intake. The study found that salt increased food and calorie intake, regardless of the food’s fat content.
Summary: This trial examined the effects of alternate-day fasting (ADF) on ratings of appetite, appetite hormones and body weight.
ADF caused significant weight loss. However, it didn’t seem to increase ratings of appetite after the participants resumed their normal diets.
New Research From Around the World
Every week, dozens of nutrition articles are published. Here are summaries of the most interesting or relevant studies, categorized by subject.
- Obesity and Weight Loss
- Blood Sugar Control and Diabetes
- Heart Health
- Digestive Health
- Liver Health
- Bone Health
- Muscles and Physical Performance
- Thyroid Health
- Skin Health
- Longevity and Healthy Aging
1. Obesity and Weight Loss
Can early weight loss, eating behaviors and socioeconomic factors predict successful weight loss at 12- and 24-months in adolescents with obesity and insulin resistance participating in a randomised controlled trial?
This observational study was based on results from the RESIST study, a randomized controlled, weight-loss trial in adolescents.
The study found that early weight loss is a predictor of long-term weight loss. As a possible explanation, those who lose more weight early on may be more engaged or motivated. They were also better at resisting cravings.
A high ratio of omega-6 to omega-3, which is typical of the Western diet, has been associated with adverse health effects. Researchers have speculated that this ratio in the diet of pregnant mothers may affect the body composition of their children.
This controlled trial examined the effects of a reduced omega-6 to omega-3 ratio, containing 1,020 mg of omega-3 and 180 mg of omega-6. The study showed that the ratio was not linked with body composition when the children were 2–5 years old.
This was a cross-sectional observational study in children and adolescents, aged 4–18 years. It found no evidence that eating a meal after 8 p.m. was associated with increased calorie intake, obesity or being overweight.
This meta-analysis of randomized controlled trials concluded that following a low-carb diet reduces body weight and fat mass in obese individuals. Very-low-carb diets were especially effective.
This large, observational study in 163,820 children and adolescents, aged 3–18 years, suggests that antibiotic use early in life may increase the risk of weight gain throughout childhood and adolescence.
This observational study showed that children who liked fruit and vegetables at age 2.5 years were more likely to eat more of them at age 7, compared to those who didn’t like them at age 2.5.
Additionally, higher fruit and vegetable intake at age 7 was linked with slightly lower body mass index.
2. Blood Sugar Control and Diabetes
Carnosine is an antioxidant dipeptide found in animal-based foods and sold as a supplement. Animal studies suggest these supplements may reduce diabetes risk.
This small, randomized controlled trial in overweight and obese people showed that supplementing with carnosine, 2 grams daily for 3 months, lowered insulin and blood sugar. It also improved insulin sensitivity.
This observational study suggests that eating chocolate daily may lower insulin levels and protect against insulin resistance.
3. Heart Health
Elevated levels of homocysteine, which is a product of metabolism, have been associated with a variety of diseases, especially heart disease.
This meta-analysis concluded that supplementing with omega-3, folate, vitamin B6 and B12 is more effective at lowering homocysteine levels than omega-3 alone.
This observational study in 512,891 Chinese adults found that eating a lot of fresh fruit is strongly associated with lower blood pressure, lower blood sugar levels and a decreased risk of heart disease.
Arterial stiffness is a measure of the blood vessels’ ability to expand or contract. It specifically refers to the arteries, the blood vessels that carry blood from the heart. Increased arterial stiffness is associated with an elevated risk of heart disease.
This randomized controlled trial in 52 obese individuals found that supplementing with magnesium, 350 mg daily for 6 months, reduced a circulating marker (PWVc-F) of arterial stiffness. This suggests that magnesium may reduce the risk heart disease.
Myocardial infarction (MI), also known as a heart attack, is when blood flow to the heart, or part of the heart, is disrupted.
This observational study suggests that eating fatty fish, rather than lean fish, poultry or red meat, may reduce the risk of MI. It also found that eating unprocessed red meat rather than processed red meat was not linked with MI.
Growing evidence indicates that being low in vitamin D is a risk factor for multiple chronic diseases and death. This idea has been called the vitamin D hypothesis. Observational studies have provided mixed results.
This observational study supports the hypothesis. It showed that low levels of vitamin D were linked to an increased risk of heart disease and death from all causes.
This observational study found that circulating levels of selenium were not associated with prostate cancer. However, high levels of selenium were associated with a lower risk of high-grade prostate cancer.
This observational study indicates that eating legumes may protect against prostate cancer. Conversely, it suggests that eating fruit, non-starchy vegetables, potatoes and tomato products does not reduce the risk of prostate cancer.
Previous observational studies have linked heme iron from red meat, and nitrosylated heme iron from processed red meat, with an increased risk of colon cancer. This observational study supports previous evidence.
5. Digestive Health
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 cows’ milk.
Two types of beta-casein — A1 and A2 — are generally found in milk. Studies have linked A1 beta-casein with adverse health effects, but the evidence is limited. For this reason, milk containing no A1 beta-casein (A2 milk) has started to become available.
This randomized, crossover trial in people with lactose intolerance showed that drinking milk containing A1 beta-casein worsened digestive symptoms, increased inflammation and impaired cognitive speed and accuracy, compared to A2 milk.
6. Liver Health
In parts of the world, drinking water is contaminated with high amounts of arsenic, which has been associated with a variety of health problems. Arsenic in drinking water can have natural sources, but its levels have been rising due to pollution.
This observational study showed that when the concentration of arsenic in people’s drinking water is 300 μg/L or higher they are at an increased risk of non-viral liver inflammation (hepatitis) and cirrhosis.
7. Bone Health
This observational study in older adults suggests that low intake of fruit and vegetables — one serving or less per day — may increase the risk of hip fractures.
8. Muscles and Physical Performance
Eating adequate amounts of protein may help prevent the loss of muscle mass and strength as you get older. However, some researchers have speculated that the frequency of protein consumption may also play a role.
This observational study in elderly people showed that those who frequently consumed 30–45 grams of protein per meal had greater muscle mass and strength, compared to those who consumed high amounts of protein less often.
Leucine is an essential amino acid, and is the only amino acid known to stimulate muscle protein synthesis. For this reason, adequate leucine intake may reduce the loss of muscle mass and strength that occurs with aging.
This prospective observational study supports this. It suggests that greater leucine intake, combined with adequate protein intake, may lessen the loss of muscle mass associated with aging.
This randomized controlled trial examined the effects of taking vitamin D3 supplements during a 12-month weight loss program with regular strength exercises. The subjects were 218 postmenopausal women with inadequate levels of vitamin D.
Supplementing with vitamin D3 — 2,000 IU daily for a year — decreased leg strength, but did not affect changes in lean mass or bone mineral density.
Osteoarthritis is a degenerative joint disease characterized by the breakdown of cartilage in joints. The main symptoms are joint swelling, stiffness and pain.
This observational study showed that being overweight or obese was linked with an increased risk of hand, hip and knee osteoarthritis.
Mucositis is when the mucous membranes lining the digestive tract become damaged and inflamed as a result of chemo- or radiotherapy for cancer.
This meta-analysis of randomized controlled trials concluded that supplementing with glutamine — an amino acid — may reduce mucositis in the mouth.
11. Thyroid Health
Postpartum thyroiditis (PPT) is when the thyroid gland becomes inflamed in the first year after pregnancy. It may cause excessive levels of thyroid hormones (hyperthyroidism) or inadequate levels (hypothyroidism).
This human trial suggests that vitamin D supplements may benefit women with PPT.
12. Skin Health
Acne is a skin disease characterized by greasy skin, blackheads and pimples. It is most common among teenagers. Growing evidence associates acne with dietary factors, such as a high intake of foods that cause spikes in blood sugar levels.
This observational study showed that people with acne had a diet with a higher overall glycemic index and glycemic load, compared to people with healthy skin. Their levels of the hormone adiponectin were also significantly higher.
13. Longevity and Healthy Aging
Telomeres are sequences of DNA at the ends of DNA strands. Their length shortens with age, making them a marker of aging.
This observational study showed that greater adherence to the Mediterranean diet, which may indicate healthy lifestyle habits, was associated with longer telomeres.