By Life Extension
Take Your Vitamin D with Largest Meal of the Day
Vitamin D is a fat-soluble nutrient that does not absorb well on an empty stomach or with a small meal.
A study evaluated a small group of people who took vitamin D on an empty stomach or with a light meal. When these people were instructed instead to take their vitamin D with the largest meal of the day, there was a remarkable 56.7% increase in serum blood (25-hydroxyvitamin D) levels after two to three months.*
This study, conducted at the Cleveland Clinic Foundation Bone Clinic, demonstrates how much better fat-soluble nutrients absorb when taken with a meal that contains some fat, which is usually the heaviest meal of the day. It helps explain why people who take higher doses of vitamin D sometimes fail to achieve optimal blood levels of 25-hydroxyvitamin D (over 50 ng/mL.)
Nutrients that should be taken with heaviest meal of the day include fish oil, lycopene, lutein, zeaxanthin, gamma tocopherol, astaxanthin, and of course, vitamin D.
* J Bone Miner Res. 2010 Apr;25(4):928-30.
Lower DHEA Levels Associated with Higher Risk of Cardiovascular Disease
The Endocrine Society's Annual Meeting was the site of a presentation of the finding of a protective effect for higher levels of dehydroepiandrosterone (DHEA) against the risk of cardiovascular events in men.*
Asa Tivesten, MD, and colleagues analyzed data from 2,416 men enrolled in the Osteoporotic Fractures in Men Sweden study. Blood samples obtained upon enrollment were analyzed for DHEA and DHEA sulfate (DHEA-S).
Over a five year follow-up, 485 cases of fatal or nonfatal cardiovascular events were documented. Having a higher serum DHEA was associated with a lower risk of cardiovascular events, as was having a higher level of DHEA-S. Men whose DHEA-S was among the lowest one-fourth participants had a 25% higher risk of events compared to the rest of the subjects, and those whose levels of both DHEA and DHEA-S were among the lowest fourth had a 34% higher risk of any major cardiovascular event.
Editor's Note: DHEA, produced by the adrenal glands, acts as a precursor to the hormones estradiol and testosterone. While some research findings have suggested an association between increased DHEA levels and a reduction in heart disease, the majority of the studies involving DHEA have been small and results have not always been conclusive.
* Endocrine Society 94th Annual Meeting, June 23, 2012 Houston.
Metformin Shows Promise for the Treatment of Pancreatic Cancer
At the Pancreatic Cancer: Progress and Challenges conference, Christopher Heeschen, MD, PhD, reported positive results for metformin in experiments involving pancreatic cancer cell cultures and mice implanted with pancreatic cancer tumors.* The drug helps eliminate cancer stem cells, a population of cells that are resistant to chemotherapy and which may be responsible for the initiation and recurrence of the disease.
Pretreatment of pancreatic ductal adenocarcinoma cancer stem cells with metformin resulted in activation of AMPK, an enzyme that helps regulate cellular energy. Treatment with a combination of gemcitabine (the standard chemotherapy for pancreatic cancer) and metformin eradicated cancer stem cells as well as other malignant cells. When Dr. Heeschen's team implanted immunocompromised mice with pancreatic cancer tumors and treated them with gemcitabine and/or metformin, animals that received both drugs had fewer tumors and a lower incidence of relapse in comparison with those that received either drug alone.
Editor's Note: Metformin is currently prescribed to diabetic patients and has shown potential as a cancer preventive and treatment, in addition to other possible uses.
* American Association for Cancer Research Pancreatic Cancer: Progress and Challenges, June 18-21, 2012, Lake Tahoe, NV.
Exercise May Be Needed for Dietary Restriction Benefits
In the journal Cell Metabolism, scientists at the Buck Institute for Research on Aging report the outcome of experiments that suggest that it may be necessary to be physically active in order to derive maximum benefit from dietary restriction (DR). Significant restriction of the intake of a particular nutrient or total calories has extended the life span of numerous species in laboratory experiments; however, researchers are still clarifying the mechanisms involved in the technique.*
In a study involving fruit flies, Pankaj Kapahi, PhD, and colleagues observed that the insects became more physically active when their protein source was restricted. The increased physical activity observed in the dietary-restricted flies was associated with greater fat synthesis and breakdown. When fat synthesis in muscle tissue was blocked, so was the life-extending benefit of dietary restriction. And in flies whose motion was limited, the extended life span that normally results from a restricted diet did not occur.
Editor's Note: The researchers additionally determined that in flies genetically engineered to overexpress the hormone AKH (Adipokinetic Hormone), metabolism and activity levels were enhanced and life span was extended, even without dietary restriction. The authors suggest that molecules such as AKH could potentially serve as a dietary restriction mimetic.
* Cell Metab. 2012 Jul 3;16:97-103.
Higher Dose Vitamin D Needed for Fracture Prevention
A pooled analysis of 11 clinical trials reported in a recent issue of the New England Journal of Medicine reveals a protective effect for high dose vitamin D supplementation against the risk of fracture in older men and women.* While 800 IU or more of the vitamin was associated with reduced fracture risk, lower doses did not appear to be effective.
Scientists analyzed data from 31,022 individuals age 65 and older who were assigned to receive oral vitamin D or a placebo in one of 11 randomized, controlled trials. Among those whose vitamin D was among the top 25% of subjects at a median dose of 800 IU per day, there was a 30% lower adjusted risk of hip fracture and a 14% lower risk of nonvertebral fractures in comparison with those whose vitamin D intake was lowest.
Editor's Note: The study found no fracture-preventive benefit for doses lower than 800 IU per day, indicating that higher doses may be needed, particularly among those at risk for osteoporosis and fracture. This study publishes what Life Extension has already used to rebut government recommendations against vitamin D.
* N Engl J Med. 2012 Jul 5;367(1):40-9.