Tag Archives: Diet Studies

Diet Infographic: Most “Macronutrient Diets” Reduce Weight & Blood Pressure In 6 Months (BMJ)

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From a BMJ Study article (April, 2020):

Compared with usual diet, moderate certainty evidence supports modest weight loss and substantial reductions in systolic and diastolic blood pressure for low carbohydrate (eg, Atkins, Zone), low fat (eg, Ornish), and moderate macronutrient (eg, DASH, Mediterranean) diets at six but not 12 months. Differences between diets are, however, generally trivial to small, implying that people can choose the diet they prefer from among many of the available diets (fig 6) without concern about the magnitude of benefits.

Introduction

The worldwide prevalence of obesity nearly tripled between 1975 and 2018.1 In response, authorities have made dietary recommendations for weight management and cardiovascular risk reduction.23 Diet programmes—some focusing on carbohydrate reduction and others on fat reduction—have been promoted widely by the media and have generated intense debates about their relative merit. Millions of people are trying to lose weight by changing their diet. Thus establishing the effect of dietary macronutrient patterns (carbohydrate reduction v fat reduction v moderate macronutrients) and popular named dietary programmes is important.

Biological and physiological mechanisms have been proposed to explain why some dietary macronutrient patterns and popular dietary programmes should be better than others. A previous network meta-analysis, however, suggested that differences in weight loss between dietary patterns and individual popular named dietary programmes are small and unlikely to be important.4 No systematic review and network meta-analysis has examined the comparative effectiveness of popular dietary programmes for reducing risk factors for cardiovascular disease, an area of continuing controversy.

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Obesity Study: “Late Night Snacking” Older Adults – Higher Fat Levels Than Early Eaters On Same Diet

From a PLOS Biology Journal study (Feb 20, 2020):

Snacking Before you sleep Keeps on the Fat PLOS Biology April 2020
Schematic: Late-evening snacking interacts with the circadian rhythm of metabolism to inhibit LO.

The major finding of this study is that the timing of feeding over the day leads to significant differences in the metabolism of an equivalent 24-h nutritional intake. Daily timing of nutrient availability coupled with daily/circadian control of metabolism drives a switch in substrate preference such that the late-evening Snack Session resulted in significantly lower LO compared to the Breakfast Session. 

Developed countries are experiencing an epidemic of obesity that leads to many serious health problems, foremost among which are increasing rates of type 2 diabetes, metabolic syndrome, cardiovascular disease, and cancer. While weight gain and obesity are primarily determined by diet and exercise, there is tremendous interest in the possibility that the daily timing of eating might have a significant impact upon weight management [13]. Many physiological processes display day/night rhythms, including feeding behavior, lipid and carbohydrate metabolism, body temperature, and sleep.

PLOS Biology StudiesThese daily oscillations are controlled by the circadian clock, which is composed of an autoregulatory biochemical mechanism that is expressed in tissues throughout the body and is coordinated by a master pacemaker located in the suprachiasmatic nuclei of the brain (aka the SCN [1,4]). The circadian system globally controls gene expression patterns so that metabolic pathways are differentially regulated over the day, including switching between carbohydrate and lipid catabolism [1,3,59]. Therefore, ingestion of the same food at different times of day could lead to differential metabolic outcomes, e.g., lipid oxidation (LO) versus accumulation; however, whether this is true or not is unclear.

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Study: Maintaining Weight Loss Tied To Healthier Eating Routines Formed Over Two-Year Period

From a New York Times online article (March 16, 2020):

New York Times How To Lose Weight and Keep It Off Study March 16 2020“Maintaining weight loss can get easier over time. Over time, less intentional effort, though not no effort, is needed to be successful. After about two years, healthy eating habits become part of the routine. Healthy choices become more automatic the longer people continue to make them. They feel weird when they don’t.”

Among the useful strategies identified in the new study is to keep lower calorie foods like fruits and vegetables more accessible. “We eat what we see,” Dr. Phelan noted. The corollary is equally important: keep high-calorie, less nourishing foods relatively inaccessible and out of sight if not out of the house entirely.

The new study led by Dr. Phelan, professor of kinesiology and public health at California Polytechnic State University, identified habits and strategies that can be keys to success for millions. Yes, like most sensible weight-loss plans, they involve healthful eating and regular physical activity. But they also include important self-monitoring practices and nonpunitive coping measures that can be the crucial to long-term weight management.

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Health Studies: “Spirulina” Improves Cardiovascular (CVD) Risk Factors, Aids In Weight Loss (BMJ)

From a BMJ Open Heart online study (March 8, 2020):

BMJ Open Heart JournalOverall, the evidence in the literature suggests that spirulina improves several well-established CVD risk factors including hyperlipidaemia and seems to provide benefits around weight loss. 

Although caloric restriction and exercise are the mainstay treatments for obesity, spirulina has shown significant benefits in aiding weight loss. The phycocyanin in spirulina contains a light-harvesting chromophore called phycocyanobilin, which is capable of inhibiting nicotinamide adenine dinucleotide phosphate hydrogen (NADPH) oxidase, a significant source of oxidative stress in adipocytes playing a key role in inducing insulin resistance and shifting adipokine and cytokine production in hypertrophied adipocytes. Thus, by suppressing adipocyte oxidative stress, spirulina may lead to systemic anti-inflammatory and insulin-sensitising effects.

BMJ Open Heart Journal Study of Spirulina Health benefits March 2020

Spirulina is both a salt and fresh water blue-green algae, which is being increasingly studied recently. Spirulina was initially classified under the plant kingdom due to its rich plant pigments and its ability to photosynthesize, but was later placed into bacterial kingdom (cyanobacteria) due to its genetic, physiological and biochemical makeup. Spirulina grows naturally in high salt alkaline water reservoirs in subtropical and tropical areas of America, Mexico, Asia and Central Africa.

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Studies: “Ultra-Processed Foods” Are 58% Of All Calories In U.S., & Obesity Epidemic’s Major Cause

From a The Guardian online article (Feb 12, 2020):

What characterizes ultra-processed foods is that they are so altered that it can be hard to recognize the underlying ingredients. These are concoctions of concoctions, engineered from ingredients that are already highly refined, such as cheap vegetable oils, flours, whey proteins and sugars, which are then whipped up into something more appetizing with the help of industrial additives such as emulsifiers. 

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From a MedPage Today online article (March 7, 2020):

The top ultra-processed foods by calorie intake were breads, beverages, cakes, Ultra-Processed Diet and Unprocessed Diet Infographiccookies and pies, salty snacks, frozen and shelf-stable dishes, pizza, and breakfast cereals.

Altogether, ultra-processed foods accounted for 58% of all calories in the U.S. diet and nearly 90% of all added sugars.

They divided foods into four categories:

  • Unprocessed or minimally processed foods: Fresh, dry, or frozen fruits or vegetables, grains, legumes, meat, fish, and milk
  • Processed culinary ingredients: Table sugar, oils, fats, salt, and other substances extracted from foods or from nature and used in kitchens to make culinary preparations
  • Processed foods: Foods manufactured with the addition of salt, sugar, or other substances of culinary use to unprocessed or minimally-processed foods, such as canned food, simple breads, and cheese
  • Ultra-processed foods: Formulations of several ingredients that — besides salt, sugar, oils, and fats — include food substances not used in culinary preparations, in particular, flavors, colors, sweeteners, emulsifiers, and other additives used to imitate sensory qualities of unprocessed or minimally-processed foods and their culinary preparations or to disguise undesirable qualities of the final product

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Health Studies: “Habitual” Supplementation Of Fish Oil (Omega-3) Lowers “All Cause Mortality” (BMJ)

From a BMJ Research study (March 4, 2020):

The BMJ podcastHabitual fish oil supplementation is associated with a 13% lower risk of all cause mortality, a 16% lower risk of CVD mortality, and a 7% lower risk of CVD events among the general population

Fish oil is a rich source of long chain omega 3 fatty acids, a group of polyunsaturated fats that primarily include eicosapentaenoic acid and docosahexaenoic acid. Initially, these compounds were recommended for daily omega 3 fatty acid supplementation for the prevention of cardiovascular disease (CVD). Consequently, the use of fish oil supplements is widespread in the United Kingdom and other developed countries.

Omega-3 Fatty Acids Cardiovascular Protection

Several mechanisms could explain the benefits for clinical outcome derived from fish oil supplementation. Firstly, the results of several studies have indicated that supplementation with omega 3 fatty acids has beneficial effects on blood pressure, plasma triglycerides, and heart rate, all of which would exert a protective effect against the development of CVD. Secondly, several trials have shown that omega 3 fatty acids can improve flow mediated arterial dilatation, which is a measure of endothelial function and health. Thirdly, omega 3 fatty acids have been shown to possess antiarrhythmic properties that could be clinically beneficial. Finally, studies have reported that fish oil can reduce thrombosis. Additionally, studies have reported that the anti-inflammatory properties of fish oil could have a preventive role in the pathophysiology of CVD outcomes. Other mechanisms could also be involved to explain the effect of fish oil on CVD outcomes.

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Diet Studies: “Eat Less, Live Longer” – Calorie Restriction Delays Age-Related Diseases (Salk)

Salk Institute logoEat less, live longer- If you want to reduce levels of inflammation throughout your body, delay the onset of age-related diseases and live longer—eat less food. That’s the conclusion of a new study by scientists from the US and China that provides the most detailed report to date of the cellular effects of a calorie-restricted diet in rats.

(Salk News, February 27, 2020)

While the benefits of caloric restriction have long been known, the new results show how this restriction can protect against aging in cellular pathways, as detailed in Cell on February 27, 2020.

Aging is the highest risk factor for many human diseases, including cancer, dementia, diabetes and metabolic syndrome. Caloric restriction has been shown in animal models to be one of the most effective interventions against these age-related diseases. And although researchers know that individual cells undergo many changes as an organism ages, they have not known how caloric restriction might influence these changes.

In the new paper, Belmonte and his collaborators—including three alumni of his Salk lab who are now professors running their own research programs in China—compared rats who ate 30 percent fewer calories with rats on normal diets. The animals’ diets were controlled from age 18 months through 27 months. (In humans, this would be roughly equivalent to someone following a calorie-restricted diet from age 50 through 70.)

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Diet Studies: Repeated “Diet Switching” Found To Increase Mortality Risks

From a Science Journal study (Feb 21, 2020):

Science Advances Feb 2020We suggest this increase in mortality seen on DR in the 4-day switch treatment is due to either accrued physiological costs or more probable, a carryover of deaths directly resulting from the rich diet, but recorded on the DR diet.

A closer examination of the timing of mortality within the 4-day switching paradigm showed that the mortality response was strongest in the second 48 hours after exposure to both DR and rich diets.

Ageing has attracted extensive scientific interest, from both a fundamental and biomedical perspective. Dietary restriction (DR) extends health and life span across taxa, from baker’s yeast to mice, with very few exceptions (12). The reduction in total calories—or restriction of macronutrients, such as protein—extends life span reliably (35). Although the precise universal mechanisms that connect DR to ageing remain elusive, translation of DR’s health benefits to human medicine is deemed possible. The widespread assumption of DR’s translational potential originates from the notion that DR’s beneficial effects are facilitated by shared evolutionary conserved mechanisms, as beneficial effects of DR are observed across taxa.

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Podcast: “Intermittent Fasting” Study Author Mark P. Mattson MD On Diet’s Health Benefits

NEJM Journal WatchIntermittent fasting has salutary effects. Listen how Dr. Mark P. Mattson, co-author of a recent NEJM review on the topic, assesses the practice — and how he’s managed to skip breakfast for the past 30 years or so.

Evidence is accumulating that eating in a 6-hour period and fasting for 18 hours can trigger a metabolic switch from glucose-based to ketone-based energy, with increased stress resistance, increased longevity, and a decreased incidence of diseases, including cancer and obesity.

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Dementia: Antioxidant “Flavonols” From Fruits & Vegetables Lower Alzheimer’s Risk By 48%

From a Rush University Medical Center online article:

The study found that participants in the group with the highest flavonol consumption were 48% less likely to develop Alzheimer’s dementia later on in life than participants with the lowest level. Of the 186 people in the highest group, 28 people, or 15%, developed Alzheimer’s dementia, compared to 54 people, or 30%, of the 182 people in the lowest group.

flavonols infographic Neurology Journal January 29 2020

People who eat or drink more foods with flavonol, which is found in nearly all fruits and vegetables, plus tea and wine, may be less likely to develop Alzheimer’s dementia, according to the Rush researchers. They published the results of their study in the Jan. 29 online issue of Neurology.

Flavonols are a type of flavonoid, a group of phytochemicals found in plant pigments. They are known for their beneficial effects on health due to their antioxidant and anti-inflammatory properties.

A total of 921 people with an average age of 81 participated in the Neurology study. These participants did not have Alzheimer’s dementia when starting the study.

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