FEBRUARY 2016 - Volume 2016, Issue 2                                       

In This Issue….
                                                                           

  • High-dose vitamin D benefits glucose metabolism
  • Vitamin A may reprogram gene expression linked to sugar cravings
  • Vitamin C kills colon cancer cells, potential mechanism explained
  • Selenium lowers cardiovascular risk, but only within a narrow range
  • Metabolic syndrome may increase vitamin E requirement
  • Can higher omega 3 fatty acid levels make teenagers smarter?

 

CLINICAL UPDATE – High-dose vitamin D benefits glucose metabolism
In this randomized, double-blind, placebo-controlled clinical trial, patients with diagnosed depression were given either placebo (n=20) or high dose of 50,000 IU vitamin D (n=20) once per week for eight weeks. Depression was alleviated in the supplemented group although more dramatic changes were seen in cardiometabolic biomarkers. For example, those in the vitamin D group had significantly lower insulin, lower HOMA-IR (homeostasis model assessment of insulin resistance), better β-cell function, higher antioxidant status and higher levels of the powerful antioxidant glutathione, when compared to patients taking placebo. (Journal of Nutrition, February 2016)

LINK to ABSTRACT Vitamin D Supplementation Affects the Beck Depression Inventory, Insulin Resistance, and Biomarkers of Oxidative Stress in Patients with Major Depressive Disorder: A Randomized, Controlled Clinical Trial.

 

 

CLINICAL UPDATE – Vitamin A may re-program gene expression linked to sugar cravings
Pregnant rats were fed one of the following three diets: (1) a regular multivitamin diet, (2) a regular multivitamin plus a 10-fold increase in vitamin A or (3) a 10-fold increase in multivitamin but regular vitamin A amounts. Interestingly, the offspring that were fed the super high vitamin A diet displayed altered gene expression, which manifested clinically as a decreased preference for sugar. Specifically, genes in the region of the brain associated with reward and pleasure – the hypothalamus dopaminergic reward system – were epigenetically altered (more methylated) in such a way that the desire for sugar was decreased, but only in those rats fed very high vitamin A during gestation. (Journal of Nutritional Biochemistry, January 2016)

LINK to ABSTRACT High vitamin A intake during pregnancy modifies dopaminergic reward system and decreases preference for sucrose in Wistar rat offspring.

 

 

CLINICAL UPDATE – Vitamin C kills colon cancer cells, potential mechanism explained
The mechanism behind high-dose vitamin C and its lethal effect on a specific type of colon cancer cells is due to the inactivation of a specific enzyme that metabolizes glucose. Specifically, when high levels of vitamin C are exposed to colorectal cancer cells, the cancer cells increase their uptake of oxidized vitamin C. High amounts of oxidized vitamin C use up the antioxidant glutathione in cancer cells. Since the glutathione becomes depleted in cancer cells, an increase in reactive oxygen species occurs in the cancer cells and this ultimately inactivates the enzyme (called GAPDH – glyceraldehye 3-phosphate dehydrogenase) that cancer cells use to metabolize glucose and survive. Since the cancer cells cannot metabolize glucose, they are essentially “starved” and die, and tumor growth is impaired. This lethal effect of vitamin C on colon cancer cells only applied to colon cancer cells that have a specific genetic mutation, but these mutations occur in more than half of all human colon cancers. (Science, December 2015)

LINK to ABSTRACT Vitamin C selectively kills KRAS and BRAF mutant colorectal cancer cells by targeting GAPDH.

 

 

CLINICAL UPDATE – Metabolic syndrome may increase vitamin E requirement
One of the eight forms of vitamin E – α-tocopherol – is less bioavailable in people with metabolic syndrome, suggests this paper. Compared with healthy people, those with metabolic syndrome have lower α-tocopherol absorption and lower levels of vitamin E in several of their lipoproteins, including VLDL, LDL and HDL. In addition, low vitamin E was linked to higher oxidized LDL and higher inflammation (CRP, IL-10 and Il-6). The authors suggest that inflammation present in metabolic syndrome patients may impair absorption of vitamin E in the gut or impair vitamin E transport in the liver or both, thus supporting “higher dietary α-tocopherol requirements for metabolic syndrome adults.” (American Journal of Clinical Nutrition, November 2015)

LINK to ABSTRACT α-Tocopherol bioavailability is lower in adults with metabolic syndrome regardless of dairy fat co-ingestion: a randomized, double-blind, crossover trial.

 

 

 

 

CLINICAL UPDATE – Selenium lowers cardiovascular risk, but only within a narrow range
In this meta-analysis, 32 studies on selenium and cardiovascular risk were reviewed – 16 prospective observational studies and 16 randomized controlled trials. Interestingly, the authors found that oral selenium supplementation did not affect cardiovascular risk. However, they did conclude that within a narrow range, higher blood levels of selenium significantly reduced heart disease risk, but outside this range the correlation disappears. This suggests that targeted supplementation is perhaps ideal compared to the “if some is good, more is better” approach to supplementation, especially for the mineral selenium. (European Journal of Clinical Nutrition, February 2016)

LINK to ABSTRACT Selenium status and cardiovascular diseases: meta-analysis of prospective observational studies and randomized controlled trials.

 

 

 

CLINICAL UPDATE – Can higher omega 3 fatty acid levels make teenagers smarter?
266 normal adolescents (aged 13-15 years) in the Netherlands completed this study, which measured omega 3 fatty acid levels on each teenager who was then required to take several tests designed to measure cognition and mental performance. On average, the omega 3 level was 3.83% and the researchers showed that those teenagers with higher omega 3 values demonstrated higher information processing speed and less impulsivity.

Specifically, students with higher omega 3 values had fewer errors of omission on a standardized test (called the D2 test) which is designed to quantify inattention via visual scanning speed. The authors state those with higher omega 3 values paid more attention than students with a lower omega 3 value. Similarly, scores on a test developed to test mental processing speed (called the LDST – Letter Digit Substitution Test) were higher in students with a higher omega 3 value. (Nutrients, January 2016)

LINK to ABSTRACT Association between Blood Omega-3 Index and Cognition in Typically Developing Dutch Adolescents. LINK to FREE FULL TEXT