4 Matching Annotations
  1. Apr 2019
    1. Klotho-deficient mice have accelerated aging phenotypes, whereas overexpression of Klotho in mice extends lifespan. Klotho is an anti-aging single-pass membrane protein predominantly produced in the kidney, with shedding of the amino-terminal extracellular domain into the systemic circulation. Circulating levels of soluble Klotho decrease with age, and the klotho gene is associated with increased risk of age-related diseases. The three forms of Klotho protein have distinct functions. Membrane Klotho forms a complex with fibroblast growth factor (FGF) receptors, functions as an obligatory co-receptor for FGF23, which is involved in aging and the development of chronic diseases via regulation of Pi and vitamin D metabolism. Secreted Klotho functions as a humoral factor with pleiotropic activities including regulation of oxidative stress, growth factor signaling, and ion homeostasis. Secreted Klotho is also involved in organ protection. The intracellular form of Klotho suppresses inflammation-mediated cellular senescence and mineral metabolism. Herein we provide a brief overview of the structure and function and recent research about Klotho.
  2. May 2017
    1. Another study, published at the end of March, included 2,303 healthy postmenopausal women randomly assigned to take vitamin D and calcium supplements or a placebo. The supplements did not protect the women against cancer, the researchers concluded.

      This is interesting in that it is techinically accurate - the difference between the groups was statistically not significant at p=0.06. "A new diagnosis of cancer was confirmed in 109 participants, 45 (3.89%) in the vitamin D3 + calcium group and 64 (5.58%) in the placebo group (difference, 1.69% [95% CI, -0.06% to 3.46%]; P = .06)"

      The key points is that cancer is that only 5% of people in the study got a new diagnosis of cancer in 4 years, which is a small percentage, and yet the p value was very close to significance.

      Now, non-signifcant is non-significant, however it is unfortunately incredibly common for studies to report higher p valiues as a trend towards significant, a clinically significant change that almost reached statistical significance etc. That the authors adhered so strictly to the standards for significance in the case of vtiamin D, where so few do anymore in other studies, is curious.

    2. One study with 5,108 participants, published this month in JAMA Cardiology, found that vitamin D did not prevent heart attacks.

      This study is one of a number recently that for some incomprehensible reason has decided that monthly dosing of vitamin D is perfectly fine to test. "Interventions Oral vitamin D3 in an initial dose of 200 000 IU, followed a month later by monthly doses of 100 000 IU, or placebo for a median of 3.3 years (range, 2.5-4.2 years)."

      The conclusion from this study is valid only for monthly dosing, not for daily dosing.

      Another example of a study that used monthly dosing and saw a negative effect in falls in elderly - http://jamanetwork.com/journals/jamainternalmedicine/fullarticle/10.1001/jamainternmed.2015.7148

    3. randomized trials had found no particular benefit for healthy people to have blood levels above 20 nanograms per milliliter.

      This is just a straight out lie, as well as an example of misdirection. There are an incredible amount of trials showing associations between low vitamin D levels and various diseases such as cancer, heart disease, depression. Randomized trials are not the only evidence. However, there are randomized trials - as an example - "Cancer incidence was lower in women who received vitamin D/calcium than in those who received the placebo (HR = 0.68, 95% CI = 0.46-0.99; P < 0.05). When analysis was confined to cancers diagnosed after the first year, the HR for the group who received vitamin D/calcium was 0.65 (95% CI = 0.42 to 0.99; P <0.05). In proportional hazards modeling, both treatment group and serum 25(OH)D concentration after one year of intervention were significant predictors of cancer risk. Conclusions Supplementing with 2000 IU/day of vitamin D3 and 1500 mg/day of calcium substantially reduced risk of all cancers combined. This finding provides great impetus for improving vitamin D status through advances in vitamin D nutritional policy." https://apha.confex.com/apha/144am/meetingapp.cgi/Paper/368368