Vitamin D synthesis is TEAMWORK!
Skin: 7-dehydrocholesterol + UVB = previtamin D3.
Liver: Previtamin D3 –> 25(OH)-Vitamin D3.
Kidney: 25(OH)-Vitamin D3 –> 1,25(OH)2-Vitamin D3 if you need it or 24,25(OH)2-Vitamin D3 if you don’t.
N.B. one of the major regulatory pathways occurs in skin: if you’re getting a lot of sunlight, then skin darkens to block this step. Supplemental and dietary Vitamin D3 bypass this… but the dietary Vitamin D supply rarely produces toxicity because it’s not very abundant. In other words, sunlight Vitamin D never reaches toxic levels. Supps could (rare, but possible).
Disclaimer: I’m not against Vit D supps, but prefer sunlight whenever possible.
The other major regulatory step is in the kidney. Production of 1,25(OH)2-Vitamin D3 is tightly regulated — so blood levels don’t decline until your very deficient… so 25(OH)-Vitamin D3 is a better indicator of skin production and dietary intake.
Disclaimer #2: this post is not about any of the pleiotropic effects of Vitamin D or D supps, which range in value from worthless to helpful to possibly harmful.
For some of that stuff, see:
Vitamin D: still a scam, still immunosuppressive… by Jane Plain
The Vitamin D seminar by Ivor Cummins
Vitamin D 101 by Kris Gunnars
The Vitamin D Debacle with Ivor Cummins and Sam Feltham
all of the above are more pro-D supps than me, which I find perfectly OK.
Why Low Carb?
OmniCarb (Sacks et al., 2014)
Study design & results in a nutshell:
5 weeks, low(ish) vs. high carb (40 vs. 58%) with the calorie difference split between protein (23 vs. 16%) and fat (37 vs. 27%). In other words, the low(ish) carb diet was higher in protein and fat. And there was 2 versions of each diet — a high and low glycemic index. Lots of crossing over; all in all, weak intervention but decent study design & execution.
Aaaand nothing drastic happened. Goal was insulin sensitivity, not weight loss.
1) The participants were relatively healthy at baseline. Anyone on meds was excluded. Average BMI 32. Mostly educated non-smokers. This population is expected to respond reasonably well to any diet (wrt body weight… see next point).
2) “Calorie intake was adjusted to maintain initial body weight.”
^^^this really knocks the wind out of low carb. One of the big benefits of cutting carbs is spontaneous appetite suppression –- two points here: 1) this effect is most prominent in obese IR; and 2) it is more relevant to weight loss. By not targeting insulin resistant and/or type 2 diabetics, and feeding specifically to prevent weight loss, I ask you this: Why Low Carb?
3) the biggest difference between the two diets was carbs (45% higher in low[ish] fat group), but the biggest difference from baseline, was protein in the LC group (53% increase). In other words, the Low Carb group had their carbs decreased from 50 to 40% of calories. *meh*
4) Body composition wasn’t assessed; so even if LCHP induced nutrient partitioning and improved body comp, we wouldn’t know it.
5) Everyone was eating cereal or oatmeal for breakfast, bread with most meals, and pasta or rice for dinner. What did you expect? Really?
Prior posts in what seems to be developing into a series of rants:
2 New Diet Studies
CICO and rant
Posted in Advanced nutrition, diet, Dietary fat, Energy balance, fat, Grains, insulin, Protein
Tagged body composition, calories proper, carbs, diet, energy balance, fat, protein
“Wait… what? nutrient partitioning?”
Calories In, Calories Out should not be interpreted as “eat less, move more,” but rather kept in its more meaningless form of: “if you eat less than you expend, you’ll lose weight.” At least then, it’s correct… meaningless, but correct. Eating less and moving more is no guarantee of fat loss, in part, because total energy expenditure isn’t constant and there’s that whole thing with nutrient partitioning.
For obese insulin resistant folks, this is Low Carb’s strong suit: it causes “eat less, move more”spontaneously.
For some obese insulin sensitive patients, for whatever reason, their adherence and success is greater with Low Fat. You might say, “yeah, but those suckers had to count calories.” To that, I’d counter with: “it doesn’t matter, THEY WERE MORE SUCCESSFUL COUNTING CALORIES ON LOW FAT THAN NOT COUNTING ON LOW CARB.” The spontaneous reduction in appetite obviously didn’t cut it. Do not be in denial of these cases.
Posted in Advanced nutrition, Dietary fat, Energy balance, Grains, insulin, Protein
Tagged body composition, calories, carbs, diet, energy balance, energy expenditure, fat, grains, nutrition, obesity, Paleo, protein
One of the ways dietary carbohydrate contributes to liver fat is via ChREBP: “carbohydrate-response element binding protein.” It responds to a glucose metabolite and activates transcription of lipogenic genes. Insulin helps. Ketones do the opposite (Nakagawa et al., 2013), by inhibiting the translocation of ChREBP into the nucleus where it does it’s dirty work:
More interestingly, ketones are histone deacetylase inhibitors (HDACi)… this leads to more histone acetylation. Benefits of fasting sans fasting? Modulating of acetylation is a MAJOR regulator of circadian rhythmicity.
Butyrate is another HDACi, so have some fibrous plant foods with your red wine and dark chocolate. Anti-aging (mostly worm studies, but still).
Posted in Advanced nutrition, chocolate, circadian, Dietary fat, fat, insulin, Ketosis, microbiome, wine
Tagged carbs, circadian rhythm, ketones
“Need” is a funny concept. You don’t need to eat seafood. You don’t need an appendix or legs, either.
An article about the Omega-3 Index was published in Whole Foods Magazine. Scanning through the figures, I noticed a few interesting studies.
For example, Association of marine omega-3 fatty acid levels with telomeric aging in patients with coronary heart disease (Farzaneh-Far et al., 2010)
Telomere length is believed to be a biomarker of aging: the shorter your telomeres, the faster you’re aging. In the study, they measured telomere length in white blood cells and EPA+DHA in whole blood at baseline and again 5 years later.
Quartile 1: EPA+DHA = 2.3% of the fatty acids in whole blood.
Quartile 2: 3.3%
Quartile 3: 4.3%
Quartile 4: 7.3%
Potential confounders: quartile 4 was comprised of educated rich white old non-smokers with low levels of inflammation, but the statisticians assure us those variables were controlled for… so there’s that.
I didn’t want to blog about the artificial sweetener study; to be honest, I didn’t even want to read it. I just wanted to report: 1) how many Diet Cokes are we talking about; and 2) when are you going to die.
Artificial sweeteners induce glucose intolerance by altering the gut microbiota (Suez et al., 2014)
Non-caloric artificial sweeteners (NAS) = saccharin, sucralose, and aspartame. Saccharin worked the best (worst) in the mouse study, so they tested it in humans. This was the part I found most relevant: seven healthy volunteers (5 men & 2 women, aged 28-36) who did not typically consume a lot of sweeteners were recruited and given 120 mg saccharin three times per day. 360 mg saccharin is ~10 packets of Sweet’n Low.
They are conditionally essential at best, only if docosahexaenoic acid (DHA) is lacking. We can’t synthesize omega 3 fatty acids, and indeed they do prevent/cure certain manifestations of “essential fatty acid (EFA) deficiency” (Weise et al., 1958), but DHA can do all that and more. Not that I recommend this, but a diet completely devoid of 18-carbon vege oil fatty acids will not produce EFA deficiency in the presence of DHA. (“vege,” rhymes with “wedge”)
The “parent essential oils” are linoleic acid (LA) and alpha-linolenic acid (ALA). The others, which I think are more important and the truly “essential” ones are eicosapentaenoic acid (EPA), arachidonic acid (AA), but mostly just DHA.
The first manifestation of EFA deficiency is dermatitis (Prottey et al., 1975). Some people say LA is necessary to prevent this, but it would be better phrased as “LA prevents dermatitis;” not “LA is necessary to prevent dermatitis.” All of the evidence suggesting LA is essential is in the context of DHA deficiency.
Technically, we can convert a bit of ALA to DHA, estrogen helps, testosterone doesn’t (women have better conversion rates)… and I’d speculate that the reverse is probably easier (DHA –> ALA).
Is it possible to improve the amplitude and resiliency of your circadian rhythms? Is this desirable? Yes and yes, I think.
Introducing, the aMUPA mice (Froy et al., 2006). What you need to know about ’em: they have very robust circadian rhythms. How is this assessed? Take some mice acclimated to their normal 12 hour light-dark cycle (LD) and place them in constant darkness (DD). Then take liver biopsies and measure circadian genes to see how well they still oscillate throughout the dark day; this is also known as the free-running clock, and it craps out differently in different tissues depending on a variety of factors. Most of the time, however, it’ll run for a few days in the absence of light. Circadian meal timing also helps to hasten re-entrainment.
Note in the figure below: 1) there are two distinct lines of aMUPA mice; and 2) both exhibit a greater amplitude in circadian oscillations during free-running, or DD conditions.
Posted in Advanced nutrition, angiotensin, circadian, diet, Energy balance, insulin, muscle, sleep
Tagged body composition, calories proper, circadian rhythm, energy balance, melatonin, mortality, nutrition, sleep
Don’t exacerbate afternoon diabetes with afternoon carbs.
As discussed previously [at length], insulin sensitivity in skeletal muscle follows a circadian pattern: starts out high in the morning and wanes throughout the day.
Diurnal variation in oral glucose tolerance: blood sugar and plasma insulin levels, morning, afternoon and evening (Jarrett et al., 1972)
Diurnal variation in glucose tolerance and insulin secretion in man (Carroll and Nestel, 1973)
Circadian variation of the blood glucose, plasma insulin and human growth hormone levels in response to an oral glucose load in normal subjects (Aparicio et al., 1974)
And insulin sensitivity of adipose tissue goes in the opposite direction: starts out low, and increases as the day progresses.
Diurnal variations in peripheral insulin resistance and plasma NEFA: a possible link? (Morgan et al., 1999)
The studies were standardized for a period of fasting, pre-test meal, and exercise… Following insulin, NEFA fell more slowly in the morning (149 uM/15 min) than in the evening (491 uM/15 min).
Diurnal variation in glucose tolerance: associated changes in plasma insulin, growth hormone, and non-esterified fatty acids (Zimmet et al., 1974)
Adipose tissue insulin sensitivity is greater in the evening. FFA are higher, and get shut down more rapidly, after a carb meal in the evening.
Summary: to minimize blood glucose excursions and proclivity for fat storage, eat more calories earlier in the day; this is circadian nutrient timing. And according to the Alves study, a low-carb protein-rich dinner best preserves lean tissue during weight loss.
Posted in Advanced nutrition, circadian, clamp, diet, Energy balance, insulin, Ketosis, melatonin, Protein
Tagged body composition, calories proper, carbs, circadian rhythm, energy expenditure, insulin, ketosis, melatonin, nutrition, protein