January 16, 2012
Excessive fructose intake induces the features of metabolic syndrome in healthy adult men.

Fructose, friend or foe?  It can be so beneficial to endurance athletes but so detrimental to the sedentary person.  These findings may alarm you.

Introduction:  As stated previously during sugar month, large fructose ingestion is linked with an array of health problems.  In this case, researchers link it to the metabolic syndrome, which consists of insulin resistance, dyslipidemia, abdominal obesity, and elevated blood pressure.  The metabolic syndrome often precedes the development of Type 2 diabetes.  Some of these effects are not found with glucose or diets consisting of starch.  Fructose and glucose metabolism differ and one of the consequences is depletion of ATP and production of inflammatory mediators.  The breakdown eventually leads to the production of uric acid, which may have a role in insulin resistance.  Therefore, the researchers are trying to use a drug, allopurinol, as a way to reduce uric acid and see if this can reverse the symptoms of metabolic syndrome after fructose consumption.

Methods:  Participants were 74 males who ingested 200g daily of fructose sipped throughout the day for a total of 2 weeks.  One group received the drug allopurinol and the other did not.

Results:  The following showed significant differences from baseline in regards to fructose ingestion:

  • Increase in ambulatory blood pressure with subtle greater increases in diastolic blood pressure throughout the day (number of participants who fit the criteria of metabolic syndrome for this went from 9 at baseline to 21)
  • Mean increase in fasting triglycerides
  • Reduction in HDL cholesterol
  • Increase in patients with fasting glucose meeting the criteria for metabolic syndrome ( >5.5 mmol/L)
  • Increase in fasting plasma insulin
  • Worsening of liver function tests

In regards to the group that consumed the drug (allopurinol) to decrease uric acid there were significant changes found to:

  • Protect against increases in systolic and diastolic blood pressure as well as mean arterial pressure
  • Protect against metabolic syndrome (32% participants had it before and only 34% after as compared to the fructose only group at 19% to 44% after two weeks)

Discussion/My input:  The first thing you are probably thinking is, “Nick, who would drink 200g of fructose per day, this study is not practical.”  Well, here is an alarming fact; the upper quintile of Americans consume more than 110 g of fructose daily either as additional sugar or as high-fructose corn syrup.  That is pretty close and these changes happened in only 2 weeks!  As far as the drug, it may be something included in the future to combat the metabolic syndrome; however, these results cannot be related to obese individuals or even women.  The researchers state that fructose metabolism can vary between genders.  Once again, fructose might not be the sole reason for the obesity epidemic, but it does lend credence to that notion.

Perez-Pozo et al Int J Obes (Lond). 2010 Mar;34(3):454-61

August 29, 2011
70%

Amount of energy provided by lipid catabolism in resting muscle.

Smith et al Int J Biochem Cell Biol. 2005; 37: 2047-2063.

August 18, 2011
Restricting Calories Even While on a High-Fat Diet Improves Health

It is hard to establish behavior changes with many individuals when it comes to diets.  As you know, the westernized diet is high in fat and leads to complications with health.  Every trainer will tell their clients to eat “healthier”.  Well what if we didn’t have to eat healthier for the preservation of our lifespan and well-being?  What if we could just eat slightly less of the bad food and receive improvements in health?  Now all the personal trainers and nutritionists say at once—blasphemy!

Introduction:  Few studies have focused on dietary restriction (DR) of a high-fat diet (HFD) in regards to improvement on health.  This is in fact more relevant to the dietary status of society.  Thus, scientists put mice on a HFD (30% of calories from fat) and restricted their dietary intake to better understand changes in health.

Results:  HF-DR (high-fat diet restricted) mice lost significantly more body weight (which stabilzed after the first 5 weeks) as well as white-adipose tissue depots than mice receiving the high-fat diet but not the restriction in calories.  HF-DR increased their insulin sensitivity as well as significantly lower levels of serum glucose and insulin.  HF-DR also decreased their cholesterol and increased their HDL to LDL ratio.  Finally, the novel technique of gene array analysis discovered significant increases in gene expression for genes involved in lipid metabolism and mitochondrial functioning.

Conclusion:  “The results of the study prove that DR can reverse the adverse effects of an initial unhealthy HF diet. Our treatment had a large influence on gene expression in WAT.  It is hypothesized that the restriction procedure has forced the metabolism of mice toward the utilization of lipids in order to effectively make use of the diet, spare carbohydrates, and to create a stable energy balance.”

My input:  Now don’t jump to the conclusion that I’m saying it is okay for individuals to keep eating poorly but eat less of it if they want to improve their health because I assure you, I’m not.  However, if you are having trouble with a client who won’t change their diet, why not just suggest eating less to start?  That way, when they lose weight initially (as the mice did in the first 5 weeks) they are receiving health benefits and you can then try to get them to change their eating habits by instructing them this will help them lose even more weight.  It is at this moment when individuals become weight stable that it is most vital for an intervention in their lifestyle.  My major critique is that the diet the researchers used consisted of 30% fat which may be kind of low for the everyday sedentary person even though the authors claim they used values similar to human western diets.  They note that studies with fat intakes as high as 55-65% did not show similar improvements in health.  However, I still like the findings of this study and think it is very practical to those who personal train and/or give nutrition/diet advice.  Well done.

Duivenvoorde et al J Mol Endocrinol. 2011 Aug 3;47(1):81-97.

June 20, 2011
Sphingomyelin (SM) is one of the major phospholipids (components of the plasma membranes of cells) of the lipid microdomains.  These are important regulators in the control of lipid entry into storage form, the lipid droplet.  In this study, researchers looked at an enzyme of this SM that you can see in this figure, SMS2.  Why is this important?  This is why: deficiency in this enzyme prevents HFD-induced fatty acid uptake and lipid droplet formation, which would lead to fatty liver, obesity, and insulin resistance.  We want this enzyme inhibited or downregulated in the body.Therefore, you are potentially looking at the next pharmaceutical target for the treatment of obesity and Type-2 diabetes by regulating the lipid domains on the plasma membranes of cells and subsequently, storage of lipid (fat).
Mitsutake et al J Biol Chem. 2011 Jun 13.

Sphingomyelin (SM) is one of the major phospholipids (components of the plasma membranes of cells) of the lipid microdomains.  These are important regulators in the control of lipid entry into storage form, the lipid droplet.  In this study, researchers looked at an enzyme of this SM that you can see in this figure, SMS2.  Why is this important?  This is why: deficiency in this enzyme prevents HFD-induced fatty acid uptake and lipid droplet formation, which would lead to fatty liver, obesity, and insulin resistance.  We want this enzyme inhibited or downregulated in the body.Therefore, you are potentially looking at the next pharmaceutical target for the treatment of obesity and Type-2 diabetes by regulating the lipid domains on the plasma membranes of cells and subsequently, storage of lipid (fat).

Mitsutake et al J Biol Chem. 2011 Jun 13.

May 10, 2011
High Fat Diet & Endurance Training

Background: Typically, there are two ways to increase the amount of intramyocellular lipids (IMCL) that the muscle uses during exercise.  One is training in the fasted state and the other is administering a high fat diet (HFD).  Another possible way is to train with little ingestion of carbohydrates and thus, low carbohydrate availability during exerise.  Therefore, the primary aim of this study was to investigate the effects of edurance training in the fasted state versus training with carbohydrate intake before training sessions on IMCL utilization during a period of a HFD.

 

Conclusion:  the current study clearly demonstrates that the administration of a hypercaloric HFD elevates IMCL content and increases the contribution of IMCL to energy provision in endurance exercise. This effect is not altered by exercise training, independent of whether the training is consistently performed in the fasted state or in the fed state.  Interestingly, a fat-rich diet elicits significant IMCL utilization during exercise in type IIa fibers, which otherwise do not exhibit exercise-induced IMCL breakdown in young healthy male volunteers.

 

My input:  The study went into a lot of molecular aspects of how the muscle changed the capacity to use lipids over glyocogen for energy.  However, for the scope of this blog, I will not go into the enzymes and other factors they investigated.  What I can say though that their methods are sound and it is unique in that the groups also utillized IMCL in Type 2a muscle fibers which are primarily more glycolytic (they use more glycogen) than Type 1 endurance fibers.

 

Practicality:  Perhaps the future of endurance performance will lead athletes to “fat load” as well as carb load for a race.  With the given HFD that the scientists administered to the subjects, there clearly is an increase in IMCL content used during exercise over glycogen which has the potential to fuel longer performances in endurance events.  While I do not recommend training in the fasted state for races, I think it would be possible to keep this method for those just doing aerobic activity for weight loss purposes.  For endurance athletes, feel free to continue ingesting carbohydrates before your events since this study showed that even with the ingestion of carbohydrates, the subjects utilized lipids for fuel.  The diet here lasted for 6 weeks but potentially for race purposes could be cut in half to ensure the muscle has the necessary IMCL stores needed to perform at your opitmal level.

 

Van Proeyen et al J Appl Physiol (May 5, 2011)