Why is this study important?

This is a randomized placebo controlled study looking into the effects of two dietary therapies, flaxseed and hesperidia, along with lifestyle intervention, in controlling cardiovascular risk in pre-diabetes.  Given the significant implications of Metabolic Syndrome and its impact on 35% of the US population alone, adding additional dietary solutions to the treatment armamentarium is critical to global healthcare and management strategies.

Key findings related to nutritional sciences:

The study findings are rather interesting.  Flaxseed is known for its beneficial qualities, adding fiber and Omega 3 fatty acids to the diet.  Hesperidin is a flavanone found in the white inner layer of citrus fruits and studies are showing that it improves insulin sensitivity and reduces insulin resistance. Together with a lifestyle intervention plan, this study demonstrated improvements in a number of metabolic factors ( waste circumference, blood pressure, lipid profiles, atherogenic indices, glucose parameters and inflammatory biomarkers).   

Clinical implications:

The study included 30g of whole flax-seed and 1g of hesperidia along with lifestyle intervention techniques, which combined, demonstrated a positive impact on the management of metabolic risk factors associated with pre-diabetes. Given the prevalence of metabolic syndrome and its rising rate, finding additional non-pharmacologic solutions that may have an impact on the management of related risk factors is important to the overall treatment and perhaps prevention of of this Metabolic Syndrome.

 

Importance of study: This study is important because the results suggest further modifications to the Mediterranean diet that include supplementation with increased amounts of plant-based proteins and inclusion of green tea and Mankai (Duckweed which is a tiny, leafy green -vegetable) may result in additional improvements in cardiometabolic risk factors.  waist circumference, blood pressure, LDL-C and greater weight loss were achieved in this small RCT study.  

Key Finding: By replacing more animal-based proteins with plant-based proteins which included green tea and Mankai (containing all 9 essential amino acids) a further reduction in waist circumference, blood pressure, LDL-C and greater weight loss were achieved on the “green Mediterranean diet than with the standard Mediterranean diet in this small randomized control trial.  

Clinical Implications: Clinical implications of this study suggest that additional reductions in meat intake and increased consumption of plant-based proteins has an even greater impact on decreasing cardiometabolic risk. Subjects following the green Mediterranean diet achieved an even greater and significant decrease in waist circumference and decrease in blood pressure which are two of the 5 risk factors for MetS.  A separate study published in the Diabetes Care Journal https://doi.org/10.2337/dc18-2319 also found that mankai may have beneficial postprandial glycemic effects.  

Diabetes Care Aug 2009, 32 (8) 1434-1436; DOI: 10.2337/dc09-0228

This study evaluated the association of the DASH diet with incidence of type 2 diabetes. The DASH diet is widely promoted for the management of hypertension but little is known about its impact on type 2 diabetes. Also, hypertension and diabetes often co-exist, and focussing on one diet may be easier for patients than following multiple and often confusing recommended diets. 

An inverse association was observed in whites (tertile 2 vs. tertile 1, OR 0.66 [95% CI 0.29–1.48]) that became significant for the most extreme contrast (tertile 3 vs. tertile 1, 0.31 [0.13–0.75]), with adjustment for covariates. No association was observed in blacks or Hispanics. The magnitude of this study’s results is noteworthy with an OR of 0.25 in the highest adherence tertile compared with the lowest. These results suggest that adherence to the DASH dietary pattern, which is based on a priori defined amounts of specific food groups, namely rich in vegetables, fruit, and low-fat dairy products, may have the potential to prevent diabetes.

One key finding from this study is that elevated consumption of fructose raises serum uric acid. Many of the food products that we consume today have high levels of fructose-containing sugar, notably high-fructose corn syrup. It would be worth noting that monitoring the intake of fructose could pose a remedy to some aspects of metabolic syndrome including hyperinsulinemia and hypertriglyceridemia. 

 In this study, the investigators noted that the use of uric acid lowering compounds was able to prevent and reverse features of metabolic syndrome. Of these were allopurinol and benzbromarone. This suggests that there are certain aspects of metabolic syndrome that can be targeted with the use of medicine. Combining medication and lifestyle modification can be quite effective treatments of metabolic syndrome.

 

Importance:  NAFLD and metabolic syndrome in general are incredibly common, especially in our population in Kentucky. While there are medications and other interventions that can be useful, prevention and reversal of disease through dietary changes is the safest and cheapest way to manage these conditions.

 

Key Finding: This study used a RCT design and split patients between a ~2000 calorie DASH diet and a ~2000 calorie standard diet. Both groups did have improvement in their metrics as a 2000 calorie diet was a decrease, but the DASH group had more improvement in BMI, NAFLD grade, greater decrease in waist and hip circumference. It also had an improvement in triglycerides, liver enzymes, insulin levels and CRP/NO (general inflammatory markers) 

 

Clinical Implications: While the DASH diet was originally studied and designed for hypertension, there have been multiple RCTs showing improvement in many other aspects of the metabolic syndrome. In this case, it showed significant improvement in multiple metrics, and this group also did another RCT with the same dietary changes in PCOS patients. So much of our money in healthcare is spent on drug and device development, and while those things are important, dietary modifications like the DASH diet and the Mediterranean diet are cost-effective and safe ways to reverse and prevent many chronic diseases associated with metabolic syndrome.

The important finding is which genes regulate AGEs metabolism (AGER1 and RAGE). AGER1 and RAGE are receptors binding AGEs to control cell response. AGER1 is an antioxidant; in contrast, RAGE induces inflammation and raises reactive oxygen species (ROS). The results exhibit that RAGE mRNA levels decrease in high-monounsaturated fatty acid-rich diet and high-complex carbohydrate-rich diet, including long-chain PUFA, then AGER1 increasing.

The study helps the patients to treat their diet, and those genes manage our metabolism. It could improve other diseases such as diabetes. Besides, the researchers develop the drugs from targeting those genes.  

Research suggests that a diet rich in whole grains has the potential to prevent and treat metabolic syndrome. Different whole grains have different health affects but whole grain rye can improve glucose homeostasis and blood lipid levels through fermentable dietary fiber and lignans. Whole grains also play a role in gut microbiota. The objective of this research study was to investigate whole grain rye alone and with lignan supplements as well as whole grain wheat diets on glucose tolerance. This research study also evaluated the role of gut microbiota enterotypes in response to intervention diets. In this 8-week crossover study, 40 men with metabolic syndrome were randomly assigned to whole grain diets. They rye diet supplemented with 280 mg secoisolariciresinol diglucoside (SDG) at 4-8 weeks. The effects of treatment were evaluated as well as the effects on microbiota composition and the role of the gut microbiota as a predictor of response to treatment were analyzed. The whole grain rye diet alone or with SDG supplementation compared with whole grain wheat did not affect glucose metabolism but reduced LDL cholesterol levels. This research study suggests that increased consumption of whole grain wheat and rye can make an impact on cardiometabolic risk factors including improved levels of LDL cholesterol. 

 

This is an important systematic review because it aimed to investigate the relation between

adoption of a Mediterranean dietary pattern and the prevalence or the risk of metabolic syndrome. In addition, this was the first study performed a quantitative meta-analysis using the overall metabolic syndrome as the outcome, and a large number of individuals were involved.

 

An important key finding of this study was that the researchers found a significant and consistent

inverse association between adherence to the Mediterranean diet and the risk of metabolic syndrome. However, long-term large-scale clinical trials are needed. 

 

The clinical implication of the study is that an RD should recommend Mediterranean diet for patients with metabolic syndrome or at risk of having metabolic syndrome. Moreover, by considering adopting Mediterranean diet for long-term, an RD should consider the cost and food availability of this diet during counseling session with patients 

 

Citation: Akhlaghi M. Dietary Approaches to Stop Hypertension (DASH): potential mechanisms of action against risk factors of the metabolic syndrome. Nutr Res Rev. 2020;33(1):1-18. doi:10.1017/S0954422419000155

                                        

Question 1:   Why is this study important?

Dietary Approaches to Stop Hypertension (DASH) is a dietary pattern rich in fruits, vegetables and low-fat dairy products, and low in meats and sweets. DASH provides good amounts of fibre, K, Ca and Mg, and limited quantities of total fat, saturated fat, cholesterol and Na. Although DASH was initially designed for the prevention or control of hypertension, using a DASH diet has other metabolic benefits. This study outlines the effects of DASH not just on HTN but also on other components of metabolic syndrome

Due to emphasis on the consumption of whole grains and low-fat dairy products and caution in consuming red meats and salt, DASH may provide a better diet composition than the Mediterranean dietary pattern against metabolic diseases.

Identify one key finding of this study and describe how it relates to nutritional sciences

Effect of DASH diet based on multiple studies are as follows. 

A meta-analysis by Siervo et al. indicates that DASH causes small reductions in systolic (–5·2 mmHg) and diastolic (–2·6 mmHg) blood pressure, total cholesterol (–7·73 mg/dl; –0·20 mmol/l) and LDL-cholesterol (–3·87 mg/dl; –0·10 mmol/l). Evidence is also promising for fasting insulin levels and fasting blood glucose. The magnitude of the change in any single risk factor is small and far to be clinically important per se. But the cumulative alterations in these risk factors can produce noticeable effects. Authors from same meta-analysis predicted that the above-mentioned changes lead to approximately 13 % decrease in the 10-year Framingham risk score for CVD.

DASH is a good alternative for Mediterranean diet specifically if they have Cardiovascular risk and Hypertension. 

What are the clinical implications of this study? 

I rarely see patients with no CVD risk but have metabolic syndrome. Almost all of them with time will develop HTN or DM, specifically with increase in obesity. Dietary choices in DASH diet likely will sync more with our population than the choices from other alternatives.  In U.S population, DASH diet will have good buy-in than Mediterranean diet. 

Obesity is known to be a contributing factor to many diseases. High levels of adipose tissue secrete adipokines and cytokines that affect nearly every organ in the body. One part of this review focuses on how these hormones contribute to Alzheimer’s disease (AD) pathology. 

Cognitive decline can be seen in animals that are fed a high fight diet (HFD). The hippocampus in these mice seems to be impaired by the HFD. Control mice and HFD-fed mice performed the same during hippocampus-independent tasks, but HFD-fed mice performed poorly compared to control counterparts in hippocampus-dependent tasks. Cognitive deficits and blood-brain barrier disruption were seen as early as 24 days after the start of the HFD. 

Increased inflammation causes the BBB to open and allows an influx of leukocytes, the anti-inflammatory molecule adiponectin is decreased with obesity, and Aβ (a key component of AD pathology) accumulates in the brain. The damaged BBB is not able to remove the plaques and this results in cognitive decline. It is clear that promoting lifestyle changes in regard to obesity can help more just your cardiovascular system!

Although metabolic syndrome is always discussed with visceral obesity, hypertension, dyslipidemia or hyper glycemia, this study focuses on MetS and MetS-induced osteoporosis. This study is important because it interestingly suggests honey as a treatment of both.

The key finding of this study is that honey is beneficial on MetS and bone metabolism because of its antioxidant, anti-inflammation, anti-obesity, anti-adipogenic, hypolipidemic, inhibition of α-amylase and α-glucosidase, antihypertensive, antidiabetic, and hypotensive effects. 

While diagnosis of MetS is evaluated if a patient’s levels are out of normal ranges in three or more out of five categories: fasting blood glucose, blood pressure, serum triglycerides, serum LDL/HDL, or central obesity, this study reports that by consuming honey, blood glucose levels, total cholesterol, triglycerides and LDL will be reduced, HDL will be increased and weight gain is hindered. Moreover, honey supports bone homeostasis by interfering effects of MetS.

This study’s clinical implication is that honey can be used as preventive and therapeutic interventions for MetS and MetS-induced osteoporosis.

It sounds too good to be true, and the study repeatedly mentions that "The underlying mechanisms of effects of honey are not clear." However, natural remedies are important in today’s world which relies on too much pharmaceutical drugs. Also, honey will be appreciated by MedS patients who have to avoid other sweetness.