Currently, we lack enough evidence to change the recommendations for calcium intake. The Tolerable Upper Intake Level (UL) for adults 19-50 years old is 2500 mg. This is well over the RDA of 1000 mg for the same age group. Calcium supplements commonly contain 600-1200 mg. When assessing your own calcium intake, keep in mind that calcium from food sources and calcium from supplements may have different outcomes.
The protocols carried out in these studies were approved by the the South West Frenchay NHS REC (15/SW/0244) (Study 1) and London Queen's Square REC (14/LO/0288) (Study 2 and 3). The studies were carried out in accordance with the recommendations of the Declaration of Helsinki, apart from pre-registration in a database. All subjects gave written informed consent in accordance with the Declaration of Helsinki.
Recent studies suggest that many of the benefits of the KD are due to the effects of ketone body metabolism. Interestingly, in studies on T2D patients, improved glycemic control, improved lipid markers, and retraction of insulin and other medications occurred before weight loss became significant. Both βHB and AcAc have been shown to decrease mitochondrial reactive oxygen species (ROS) production [36–39]. Veech et al. have summarized the potential therapeutic uses for ketone bodies [28, 40]. They have demonstrated that exogenous ketones favorably alter mitochondrial bioenergetics to reduce the mitochondrial NAD couple, oxidize the co-enzyme Q, and increase the ΔG’ (free enthalpy) of ATP hydrolysis . Ketone bodies have been shown to increase the hydraulic efficiency of the heart by 28 %, simultaneously decreasing oxygen consumption while increasing ATP production . Thus, elevated ketone bodies increase metabolic efficiency and as a consequence, reduce superoxide production and increase reduced glutathione . Sullivan et al. demonstrated that mice fed a KD for 10–12 days showed increased hippocampal uncoupling proteins, indicative of decreased mitochondrial-produced ROS . Bough et al. showed an increase of mitochondrial biogenesis in rats maintained on a KD for 4–6 weeks [44, 45]. Recently, Shimazu et al. reported that βHB is an exogenous and specific inhibitor of class I histone deacetylases (HDACs), which confers protection against oxidative stress . Ketone bodies have also been shown to suppress inflammation by decreasing the inflammatory markers TNF-a, IL-6, IL-8, MCP-1, E-selectin, I-CAM, and PAI-1 [8, 46, 47]. Therefore, it is thought that ketone bodies themselves confer many of the benefits associated with the KD.
As ketone drinks can deliver nutritional ketosis without fasting, we investigated the effect of food on KE uptake and metabolism. It is well documented that food in the gut can slow, or prevent, the uptake of small hydrophilic hydrocarbons, such as βHB (Melander, 1978; Toothaker and Welling, 1980; Horowitz et al., 1989; Fraser et al., 1995), so decreased gut βHB uptake is probably the cause of lower blood βHB following the meal. Despite higher blood βHB concentrations in the fasted state, the meal did not alter plasma AcAc. This suggests that the rate of conversion of βHB to AcAc may not match the rate of appearance of βHB following KE consumption. Alternatively, meal-induced changes in the hepatic ratio of NAD+:NADH may have altered the conversion of βHB to AcAc (Himwich et al., 1937; Desrochers et al., 1992).
Despite the recent growth of the ketone salt market, there is very little published work analyzing the effects of these products on any biomarkers or performance measurements in humans. Several studies have been carried out in rats,6,7 with blood BHB levels being relatively low (<0.5 mM) post-consumption of salt drinks. In humans, ketone salts provided peak D-BHB levels of 1 mM, whereas the same amount of BHB in a ketone ester (BD-BHB) raised blood BHB to 2.8 mM.5
Working memory involves temporarily storing and manipulating information. The game involves seeing three cards – a top card with a symbol that then moves along a track and is flipped over, exposing a new card above. The goal is to remember the symbol of the cards two cards back and indicate whether it matches the visible card or not. If you have ever played dual n-back games, this is very similar.
Dominic D’Agostino has two in-depth interviews on The Tim Ferriss Show (Part 1, Part 2). Discussion includes exogenous ketones for mitigating the onset of neurodegenerative diseases, using ketones in place of fasting for chemo-protection, benefits of ketone supplementation when consuming carbohydrates, the risks and potential toxicities of ketones.
Effects of beta-hydroxybutyrate on cognition in memory-impaired adults. – Glucose is the brain’s principal energy substrate. In Alzheimer’s disease (AD), there appears to be a pathological decrease in the brain’s ability to use glucose. Neurobiological evidence suggests that ketone bodies are an effective alternative energy substrate for the brain. Elevation of plasma ketone body levels through an oral dose of medium chain triglycerides (MCTs) may improve cognitive functioning in older adults with memory disorders. On separate days, 20 subjects with AD or mild cognitive impairment consumed a drink containing emulsified MCTs or placebo. Significant increases in levels of the ketone body beta-hydroxybutyrate (beta-OHB) were observed 90 min after treatment (P=0.007) when cognitive tests were administered. beta-OHB elevations were moderated by apolipoprotein E (APOE) genotype (P=0.036). For 4+ subjects, beta-OHB levels continued to rise between the 90 and 120 min blood draws in the treatment condition, while the beta-OHB levels of 4- subjects held constant (P<0.009). On cognitive testing, MCT treatment facilitated performance on the Alzheimer’s Disease Assessment Scale-Cognitive Subscale (ADAS-cog) for 4- subjects, but not for 4+ subjects (P=0.04). Higher ketone values were associated with greater improvement in paragraph recall with MCT treatment relative to placebo across all subjects (P=0.02). Additional research is warranted to determine the therapeutic benefits of MCTs for patients with AD and how APOE-4 status may mediate beta-OHB efficacy. (http://www.ncbi.nlm.nih.gov/pubmed/15123336)
Your brain has a very tight barrier so not everything in the blood can get through. This is called the blood brain barrier. Because your brain uses 25% of the energy that your entire body uses throughout the day, you need to make sure it is fueled appropriately. Glucose can’t directly cross the blood brain barrier. When you eat carbs, you get swings in energy that is available to cross the blood brain barrier which leads to mental fog.
Although decreases in FFA, TG and glucose occurred, there were no significant differences between the KE and KS drinks or with intake amount. Ingestion of ketone drinks significantly decreased overall mean plasma FFA from 0.7 to 0.4 mM, TG from 1.1 to 0.9 mM and glucose from 5.7 to 4.8 mM after 1 h (all p < 0.05). Concentrations were the same as at baseline by 4 h, with FFA at 0.6 mM, TG at 0.9 mM and glucose 5.1 mM (Figures 2A–C). There was a rise in insulin concentrations 30 min following all drinks, probably due to the small amount of carbohydrate in the sweetener (Figure (Figure2D2D).
All of the data I’ll present below were from an experiment I did with the help of Dominic D’Agostino and Pat Jak (who did the indirect calorimetry) in the summer of 2013. (I wrote this up immediately, but I’ve only got around to blogging about it now.) Dom is, far and away, the most knowledgeable person on the topic of exogenous ketones. Others have been at it longer, but none have the vast experiences with all possible modalities (i.e., esters versus salts, BHB versus AcAc) and the concurrent understanding of how nutritional ketosis works. If people call me keto-man (some do, as silly as it sounds), they should call Dom keto-king.
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