SuppVersity - Nutrition and Exercise Science for Everyone
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| Healthy due to calcium? |
the last three weeks we've already covered the effects of protein, fat
and vitamin D in this series about the "non-carbohydrate"
(micro-)nutrients which have an impact on your blood glucose levels (browse the previous installments).
With
vitamin D as the topic of the last installment, it appears only logical
to jump from vitamins to minerals and take a look at the "bone mineral"
calcium, of which scientists have long believed that its management was
the main, if not the only function of vitamin D.
In view of the
fact that the word "calcium" did not even appear in last week's
installment about the "sunshine vitamin", it may appear questionable,
whether it would even be worth taking a closer look at the soft gray
alkaline earth metal. As a SuppVersity reader who has read my previous articles
about calcium, you will yet be aware that this would be as
inappropriate as the shortsighted idea that the only function of 25OHD
was to control the amount of calcium in your blood and bones.
There is more to calcium than bone health, but is glucose management part of the "more"?
There
is in fact a plethora of studies to suggest that dietary calcium
(specifically from dairy products; see Fumeron. 2011) and, in some
cases, also supplements could have beneficial effects on the blood
glucose levels of healthy and diabetic subjects (in some cases w/,
sometimes w/out vitamin D supplementation; e.g. Pittas. 2007).
You can learn more about this topic at the SuppVersity
Proteins, Peptides & Blood Glucose
SFA, MUFA, PUFA & Blood Glucose
Vitamin D & Diabetes
Glucose Manager Calcium?
Read these ➲ while waiting
Fat to Blunt Insulin?
D unquestionably is a top candidate for t One of those vitamin D +
calcium studies was conducted by Joanna Mitri et al. in 2011. In their
study, the researchers tested the effects of 2000IU vitamin D
(cholecalciferol) in conjunction with 2x400 mg calcium per dayt on the
pancreatic β cell function, insulin sensitivity, and glycemia in adults
at high risk of diabetes. The marginal improvements in β cell function
minimal attenuation of the rise in HbA1c Mitri et al. observed in the
course of the 16 week study are yet by no means what study titles such
as "Regulation of adiposity and obesity risk by dietary calcium:
mechanisms and implications." (Zemel. 2002) would suggest.
The
reasons for this discrepancy will yet become obvious, if we take a look
at the results from well-controlled animal trials: While there is albeit
inconclusive evidence that high calcium diets markedly inhibit
lipogenesis, accelerate lipolysis, increase thermogenesis and suppress
fat accretion and weight gain, and conclusive evidence that they can
promote a modest energy loss through increased fecal fat excretion
(Soares. 2010), papers that would confirm direct beneficial effects of
calcium on glucose metabolism are rare: Even the often-cited effects
Beaulieu et al. observed in a 1993 study are "vitamin D depenent", i.e.
they occur only when the subjects are vitamin D depleted (interestingly,
these observations were made in the absence of vitamin D
supplementation; cf. Beaulieu. 1993).
Protein or calcium:
Specifically in the case of the "dairy calcium" studies it's difficult,
in many cases even impossible, to know whether the beneficial effects
on blood glucose homeostasis are brought about by their high calcium and
not by their high protein content and/or quality. Intervention studies
with high calcium intake as a single variable, on the other hand, are
scarce. It's thus most likely that it's the synergy of the two - a
synergy you can get in concentrated form from dairy protein supplements
(see box in the bottom line).
At least in the case of calcium Specifically in the case of the "dairy calcium" studies it's difficult,
in many cases even impossible, to know whether the beneficial effects
on blood glucose homeostasis are brought about by their high calcium and
not by their high protein content and/or quality. Intervention studies
with high calcium intake as a single variable, on the other hand, are
scarce. It's thus most likely that it's the synergy of the two - a
synergy you can get in concentrated form from dairy protein supplements
(see box in the bottom line).
supplements, the following examples from the contemporary scientific
literature do thus not support the often-heard claim that calcium
supplements would have beneficial effects on insulin sensitivity:
- As an adjunct to an energy reduced diet,
1,000mg/day of supplemental calcium will have no effect on either
insulin sensitivity or the changes in body composition (Shalileh. 2010).
guess one of the most important reasons that the myth of the
anti-diabetic effects of calcium supplements are so die-hard is the
difference between the short and long-term effects of high calcium meals
vs. diets:
- Acutely, calcium supplements will have
"beneficial" effects on the postprandial expression of hormones that are
involved in the control of blood glucose, because it will augment
the postprandial production of glucose-dependent insulinotropic peptide
(GIP), glucagon-like peptide-1 (GLP-1).
As you can see in Figure 1,
Figure
1: Difference in plasma GIP, GLP, insulin, glucose, lactate and NEFA
levels after the ingestion of a standardized breakfast w/ 248mg vs.
1,239mg calcium (Gonzalez. 2013).
the downstream effects of isocaloric breakfasts providing 0.5 g
carbohydrate/kg body mass (energy: 1,258 ± 33 kJ, 299 ± 8 kcal; protein:
11 ± 0 g; carbohydrate: 41 ± 1 g and fat: 10 ± 0 g) with either 248mg
or 1,239mg of calcium on the blood glucose levels of the young, healthy,
physically active study participants of the Gonzales study are
negligible.
On the contrary, it's not unlikely that ~150% increases in postprandial
fatty acid oxidation and the protein sparing effects of dairy calcium
Nicola Cummings et al. observed in a three-way cross-over study in which
subjects were randomly provided breakfast meals either low in dairy Ca,
high in non-dairy Ca (calcium citrate; see figure to the left, values expr. rel. to low CA), or high in dairy Ca are eventually triggered by said changes in GLP-1 & Co (Cummings. 2006).
- In
the long run, on the other hand, any beneficial effects on blood
glucose management (if they occur at all) are probably "side effects"
of the accumulating beneficial effects on lipid metabolism, body weight
and energy balance of high calcium diets. It is furthermore not clear
to which extend these benefits are eventually driven by additional /
synergistic nutrients in dairy - the "calcium source of choice" in ~90%
of the pertinent long(er) term studies.
the list of "high calcium" foods, which ranges from dairy (obviously),
over broccoli, kale, water cress, peas, beans, almonds, brazil nuts, to
sardines, salmon, apricots, and figs, it's actually no wonder that
eating a diet that's naturally high in calcium is going to be beneficial
for your glucose metabolism.
If, on the other hand, the
addition of a bunch of calcium carbonate pills on top of the standard
(obesogenic) Werstern diet, would protect you against diabesity, those
5% of the US population who are taking calcium or calcium containing
supplements on a regular basis (Radimer. 2004) would have to be lean and
insulin sensitive... needless to say that this is not the case, right?
Mind your total Ca intake if you use dairy protein:
Unless you have been bamboozled into buying overpriced overprocessed
specialty whey & casein products, the latter can easily provide you
with a whopping 200mg (whey) and 500mg (casein) of calcium per serving... maybe another reason they help you to get and stay lean and insulin sensitive?
So what's the verdict then? WhenUnless you have been bamboozled into buying overpriced overprocessed
specialty whey & casein products, the latter can easily provide you
with a whopping 200mg (whey) and 500mg (casein) of calcium per serving... maybe another reason they help you to get and stay lean and insulin sensitive?
all is said and done, there are two fundamental conclusion you can take
home from today's fourth installment of this series (browse
the previous installments). The first one is that there is ample
evidence that (a) a sufficient intake of calcium (800-1200mg total) is
an important prerequisite for optimal glucose management and that (b)
high calcium meals, due to their GLP-1-powered (learn more about GLP-1) thermogenic and "fat burning" effects are another valuable tools in your weight loss toolbox.
The second one, on the other hand, will probably sound less exciting to the supplement maniacs among the SuppVersity
readers. Conclusion #2 is after all: If you are eating a whole foods
diet with significant amounts of dairy and leafy greens in it, and
consume a calcium containing mineral water (in Germany 90% of the
tapwater qualifies as "mineral water), the use of supplements is at
best useless, at worst detrimental to your health (think of the rumors
about Ca supps and Prostate cancer, for example).
