Vitamin B(eer) 3
The great analytical reveal
Dear Brew Enthusiasts,
Please find below another instalment of The beerologist. It's Friday!
Last week I was caught up with various commitments, and when announcing this, I neglected to make sure that the email went out to everyone. Sincere apologies.
In this weeks post, we will talk about the yummy stuff yeast makes. With this, I do not refer to the volatiles, flavour compounds or alcohol that we like to enjoy. No, it's all about Vitamin B3!
We all know that a healthy life requires a healthy and balanced diet packed with all the nutrients and vitamins needed (I am starting to sound like a diet guru!). We also appreciate that certain foods contain particular nutrients that are good for us. But what is the dietary benefit of drinking beer? Is there any? Given the ingredients that go into our beers (water, malts from barley or other grains, hops, or even fruits) and the complex biochemistry that takes place during fermentation, surely beer must contain some stuff that is good for you? But to what extent does beer style matter? Do craft beers have more nutritional value than commercially brewed large scale beers?
We cannot answer all these questions with a single research project. We can, however, look at a subset of compounds that are known to have health benefits. Here, we will look at a form of vitamin B3 (nicotinamide riboside (NR)) and its precursors nicotinamide mononucleotide (NMN) and NAD+. Specifically, research groups led by Nadia Raffaelli and Andrea Osimani quantified the levels of these metabolites in ten commercial craft beers and a beer brewed in the laboratory. The teams sampled the laboratory beer throughout the fermentation process. They asked the questions: what are the levels of NR, NMN and NAD+ in craft beer? When do they appear, and are there any differences between beer styles?
The short answers to these questions are: Significant, throughout fermentation, and yes, there are differences between styles or more specifically, yeast strains.
One interesting observation was NAD+ in all the craft beers tested except for one, created with a different yeast species (S. pastorianus). As S. cerevisiae was used in all the other craft beers, suggesting that S. pastorianus (or this particular strain of this species) does not produce detectable levels of NAD+. Unfortunately, the authors found substantial variation between samples of the same beer. Due to that variation between samples, it becomes complicated to attribute differences between brands. Is any difference due to beer brand or simple variation between measurements or batches? The authors, however, could say with some confidence that beers produced with one yeast strain (S-04) tend to contain more NAD+
Interestingly, all the beers produced with the strain US-05 contained NR (nicotinamide riboside), though at varying levels. When it came to NMN, the results were inconsistent. In some batches, NMN was present, whereas, in others, it wasn't. The reasons for this are not clear, but variation in the assays, batches or sensitivity of the detection method may complicate interpretation of this work.
Finally, the authors wish to know whether any conditions may impact vitamin B3 (precursor) production. They made some interesting observations by measuring NAD+, NMN, and NR levels throughout the brewing process. The late addition of hops seemed to prompt a burst in NR production, seen as a sudden increase in NR levels. While the authors used beer without hop addition as a negative control, they did not test for the possibility that the hops themselves were the source of NR.
In contrast to NR, NAD+ levels dropped after hop addition. The mechanisms for its removal are not clear, but yeast may convert NAD+ into NR. NMN levels increased in the first three days of fermentation and remained stable for most fermentation, only to drop during beer maturation. In short, this research shows that during fermentation, yeast produces detectable vitamin B3 and its precursors, to levels that may dietary benefits.
What does this all mean?
The most important takeaway from this work is that beer contains a fair amount of vitamin B3, approaching levels found in cows milk. Does this mean that you can substitute milk with beer as a source of vitamin B3?
The jury is still out on that one. Although Vitamin B3 appears to be present in both beverages, what really matters is the efficiency with which we (our bodies) take this vitamin up. It is entirely possible that uptake from milk is more efficient (due to other compounds in milk) or vice versa!. I am not aware of any work that has tried to answer this question yet.
What is important to note is that (craft) beer could be a rich source of metabolites that are good for you. I would not want to suggest that we can make beer a staple drink in our diet. Rather, I'd recommend for anyone to sit back, relax, open up a nice (home or craft) brew and enjoy your weekend.
Edgar, The Beerologist.
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