Eat oat sprouts for AVAs

Here are three oat studies, two of them specifically on oat sprouts. The first from 2019 was cited in Don’t brew oat sprouts – eat them! for oat sprouts having “up to 25-fold increase” in avenanthramides (AVAs):

“Oat seeds were germinated, extracted, and analysed, finding 28 unique AVAs. AVAs 2p, 2c, and 2f, which are commonly described as the major AVAs, represented less than 20% of total content in seedlings.

The germinator program was: soak for 20 h at 20 °C (aeration 1 min every 10 min), followed by germination for 72 h at 25 °C (RH ≥ 99%). After the first 72 h of germination, oat seedlings were incubated for another 96 h at 30 °C (RH 70–80%).

AVA content was boosted by germination, resulting in around 25 times larger quantities found in oat seedlings.

Previous studies also showed an increase in AVA content upon germination, but to a lesser extent than in our current experiment. It used different growth conditions, namely a shorter soaking time (10–14 vs. 20 h) and their seed germination phase was performed at lower temperature and different duration (120 h at 16 °C or 72 h at 20 °C vs 96 h at 30 °C).

Additionally, they quantified AVAs 2p, 2c, 2f, and 3f but also observed a large number of unknown peaks in the UV 340 nm chromatogram. Based on the wide variety of AVAs annotated in our work, many of these peaks probably corresponded to other AVAs, but they were not identified and quantified as such.” “Mass spectrometric characterisation of avenanthramides and enhancing their production by germination of oat (Avena sativa)”

No measurements were taken at three days when germination parameters changed. These researchers didn’t bother to take any samples between Hours 0 and 168. This lack of germination-stage evidence limited findings’ utility to other researchers.

Was this study designed to create a headline rather than useful germination-stage information? Why obliquely and directly fault another study in the Abstract, Results and Discussion, and Conclusion sections for being performed more than a decade earlier, without subsequent advancements in science and technology?

Contrast this study’s design with 2020 Oat sprouts analysis which took measurements under 18 different conditions (hulled / dehulled seeds of two oat varieties, for 1-to-9 days, at 12-to-20°C). Those researchers produced evidence to support many further studies, such as:

“Presence / absence of hull might determine different effects of germination conditions on α-amylase, protease, and lipase activities.”

The referenced disparaged 2007 study:

“..investigated the effect of a steeping and germination process, using a pilot plant malting system, on content of AVAs and other phenolic compounds. This was performed to gain a more collective and comparative picture of what happens to phenolic compounds in the oat kernel during germination.

Steeping and germination was performed at two different temperatures, 16 and 20°C. Three closely related North American covered oat cultivars were steeped to 45% moisture, which took 10, 12, and 14 h for Vista, Gem, and Dane, respectively.

After steeping, oat grains were drained and samples were germinated at 16°C for 120 h or at 20°C for 72 h (due to a machine breakdown, the 20°C experiment had to be stopped at 72 h of germination). Sampling during germination was carried out at set hours (for 16°C at 12, 24, 48, 72, 96 and 120 h and for 20°C at 12, 24, 48 and 72 h).

Chromatogram of AVAs and other phenols from cultivar Dane (16°C treatment). Peaks for AVAs 2c, 2p, 2f and 3f are identified. Unknown peaks are numbered in order of appearance (from 1-21). For isolation and identification of AVA 3f the commercial product SPC-flakes, purchased in a health food shop, was used.

An increase in AVA content of germinated seeds, as compared to raw grains, was observed for Dane (125%, p < 0.001) and for Vista (29%, p = 0.007). HHT [avenanthramide-synthesizing enzyme] activity increased 62% (p = 0.014) in Dane, whereas no change was detected in Vista and Gem. This increase started early in germination to reach its maximum at 96 h of germination.

Effects of temperature on AVAs 2c, 2p and 2f, and activities of HHT and PO, was less important than time of steeping, or time of germination, or cultivar. However, almost all unknown compounds were affected by temperature, indicating the importance of this factor.” “Avenanthramide content and related enzyme activities in oats as affected by steeping and germination” (not freely available)

This study’s HHT (avenanthramide-synthesizing enzyme) maximum-at-96-hours finding may be what I tasted in Sprouting hulless oats, where that variety’s sprouts improved their sweetness and enzymes between Days 3 and 4. Did an extra day improve AVA content?

So their pilot malting system broke down. They had to get an analysis standard from a health food store. And there were many unknowns due to 2007 science and technology.

Despite difficulties, germination-stage samples produced evidence and analyses other people could use more than a decade later.

A 2020 study cited the first study for basic, not headline, information:

“There are various potential mechanisms for AVAs anti-inflammatory effects, including inhibition of lipoxygenases (LOX), which catalyse oxygenation of polyunsaturated fatty acids into potent signal molecules involved in inflammatory processes.

It was found that AVAs comprising caffeic or sinapic acid exhibited significant lipoxygenase inhibition (60–90%), whereas low or no inhibition was observed with AVAs containing p-coumaric or ferulic acid.

Corresponding free cinnamic acids, AVA analogue Tranilast® and LOX inhibitor trans-resveratrol were included for comparison. Trans-resveratrol showed inhibition, whereas no difference in inhibition was seen on comparing AVAs with their free corresponding cinnamic acids, which implies that the anthranilic acid part of the avenanthramide molecule does not affect inhibition.

Whether dietary AVAs at intake levels normally achieved through consumption of oat products exert LOX inhibitory activity in vivo, and thereby inhibit production of pro-inflammatory compounds, remains to be elucidated. In this context it may also be of importance to emphasize that lipid content in groats of various oat cultivars is comparably high (49–135 g kg−1) and that LA [linoleic acid (C18:2, n-6)] and ALA [α-linolenic acid (C18:3, n-3)] comprise about 40% and 1%, respectively, of fatty acids.

Consumption of oats has been linked to a decreased risk of several chronic diseases, and AVAs contribute to protective effects. This study suggests that avenanthramides comprising caffeic acid or sinapic acid partly exert their antioxidant and anti-inflammatory effects via lipoxygenase inhibition.” “Avenanthramides as lipoxygenase inhibitors”

Tampa’s Riverwalk


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