Study under review: Effects of step-wise increases in dietary carbohydrate on circulating saturated fatty acids and palmitoleic acid in adults with metabolic syndrome
Saturated fat reduction has long been a major target of dietary guidelines, although recent meta-analyses have failed to show an association with heart disease. Current recommendations in the U.S. include limiting saturated fat intake to less than 10% of total energy intake. However, a reduction in fat intake typically leads to an increase in carbohydrate intake. A consequence of overconsumption of carbohydrates is increased de novo lipogenesis. DNL is a process which involves the synthesis of fatty acids from non-lipid sources, such as carbohydrates or amino acids.
Interestingly, even energy-balanced diets, and single-meal consumption of carbohydrates above the normal oxidative capacity of the body have been shown to increase DNL. The percentage of ingested carbohydrate contributing to DNL is however quite minor in those who aren’t insulin resistant and overfeeding on refined carbohydrate.
The major end-product of DNL is the saturated fat palmitic acid (denoted 16:0, referring to 16 carbons and zero double bonds), which can be desaturated within the body to form the monounsaturated fat palmitoleic acid (16:1). Higher blood levels of palmitoleic acid have been associated with an increased risk of metabolic syndrome and greater amount of inflammatory markers. Palmitoleic has mixed evidence however, also being associated with some positive biomarkers such as higher HDL and greater insulin sensitivity. Divergent impacts could be due to the effects of different lifestyle factors and different physiological conditions (such as how much of DNL is from adipose tissue versus from the liver).
This study sought to assess how incremental changes in dietary carbohydrate intake and decreases in saturated fat intake affect plasma saturated fatty acid and palmitoleic acid levels. The study was conducted in adults with metabolic syndrome under hypocaloric conditions.
Saturated fat is commonly targeted for reduction by dietary guidelines. This typically leads to an increase in carbohydrate intake, which at high levels may cause the body to create fats through de novo lipogenesis. This study investigated several levels of saturated fat and carb intake to see how they affected plasma saturated fats and palmitoleic acid.
Other Articles in Issue #03 (January 2015)
Heart benefits of alcohol may not apply to everyone
CETP TaqiB genotype modifies the association between alcohol and coronary heart disease: The INTERGENE case-control study.
Type 2 diabetes: a preventable disease
A look at the increase in global diabetes risk and the reason behind the growing rate of type 2 diabetes diagnosis.
Whence the hype?
The association between exaggeration in health related science news and academic press releases: retrospective observational study.
Running on empty: can we chase the fat away?
Body composition changes associated with fasted versus non-fasted aerobic exercise.
Fitting into your genes: do genetic testing-based dietary recommendations work?
Disclosure of genetic information and change in dietary intake: a randomized controlled trial.
Combating obesity through intermittent fasting
Time-restricted feeding is a preventative and therapeutic intervention against diverse nutritional challenges.
How does a lifetime of marijuana use affect the brain?
Long-term effects of marijuana on the brain.
A mouse’s microbiome may cause its brain to leak
The gut microbiota influences blood-brain barrier permeability in mice.
- Interview: Stuart M. Phillips, Ph.D., FACN, FACSM
- Interview: Ramsey Nijem