|It’s worth peeling the protective layer scientists use to cover up potential methodological holes in practical relevance.|
Studies usually make it to the SuppVersity news if they are educative, informative, or practically relevant. In the case of the latest paper by Emilie Lindahl et al. (2020), one could – at a surface level – argue that all three criteria apply.
But hey, this is the SuppVersity so we’re going unpeel the surface and look for cancerous growth in the methodology section 🤣…
In their study, the scientists from the “Department of Food Science” at the Aarhus University investigated the effect of “complexation” of vitamin D3 and either whey or casein (#caseinate) protein on the bioavailability of the sunshine vitamin.
For some time, researchers have known that milk proteins have the astounding ability to self-assemble and form complexes with otherwise poorly soluble compounds (see my previous article about buttermilk + curcumin fermentation). This makes whey, casein, and natural mixe of both particularly interesting as ‘nutrient delivery shuttles’ – shuttles.
|Figure 1: Area under curve (AUC) for vitamin D3 (left) and 25-hydroxyvitamin D3 (right); 24,25-dihydroxyvitamin (not shown) reacted similarly to 25-OHD levels – long-term effect unknown, though.|
In that, the Danish researchers are not the first to suspect that these proteins or specific peptides n them could “have a potential for improving stability and bioaccessibility of vitamin D.” And indeed, Lindahl et al. point out that Abbasi et al. as early as in 2014 that encapsulation with whey protein isolate increased the stability of vitamin D3 during storage (Lindahl 2020) – Would it do the same during the transit through your gastrointestinal tract?
|D3 and Mg Supplements not mandatory w/ sun + balanced diet|
Also, don’t forget your magnesium! As you’ve learned from this 2018 news article here at the SuppVersity the macro-mineral that’s in short supply on the standard American diet, is a prerequisite for optimal 25OHD management – bi-directionally, i.e. it will normalize both, high and low 25OHD levels (learn more)!
Well, to be honest, the word ‘your’ in ‘your gastrointestinal tract’ is not exactly accurate. After all, the study was done in Sprague-Dawley rats (n = 78) who were administered 840 IU vitamin D3 (that’s 1.3x the amount they get from chow | in humans we may be talking about 1,100IU/d) dissolved in ethanol and either (i) complexed with whey protein isolate (protein : vitamin ration 2 : 1), (ii) complexed with caseinate (protein : vitamin ration 2 : 1), or (iii) provided in a water solution. The scientists analyzed the animals’ blood for the concentration of vitamin D3, 25-hydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 before and 2, 3, 4, 5, 6, 7, 8, and 10 hours after administration of vitamin D3.
“Significant effects of complexation on serum concentrations of vitamin D3, 25-hydroxyvitamin D3 and 24,25-dihydroxyvitamin D3 were demonstrated,” the abstract highlights.
When the two treatments were compared, “the complexation with whey protein isolate resulted in the fastest and highest absorption of vitamin D3 while an effect of complexation with caseinate was evident but more modest and non-significant” (Lindahl 2020).
The authors propose that the reason is an improvement of vitamin D3s solubility after complexion with whey protein, with the resulting molecule being protected against degradation in the acidic environment in the stomach. In view of casein’s tendency to aggregate (not solve/dilute) in the acidic environment of the stomach, this hypothesis may also explain why the micellar casein Considering the properties of whey protein and caseinate, where whey protein exerts high solubility in the gastrointestinal tract while casein can be expected to aggregate in the stomach, the present data indicate that solubility in the gastrointestinal tract is of utmost importance for bioaccessibility of vitamin D3… in theory, ’cause the aggregation effect is significantly reduced for sodium caseinate (vs. micellar caseinate) as it was used in the study at hand and is often found in cheap(er) protein powders. This leaves room not just for alternative explanations (e.g. certain peptides that are whey-specific may do the trick) and warrants testing if the micelle-structure of real casein doesn’t provide additional benefits that couldn’t be observed with the sodium caseinate in the study at hand.
- Abbasi, Azam, et al. “Stability of vitamin D3 encapsulated in nanoparticles of whey protein isolate.” Food chemistry 143 (2014): 379-383.
- Lindahl, Emilie I., et al. “Milk protein complexation enhances post prandial vitamin D3 absorption in rats.” Food & Function (2020).