Are natural wines healthier?

Natural wines, made without additives and from organically grown grapes, should be healthier, right? Scientifically, it’s harder to prove than you might think, and it is possible that some manipulated wines may actually have benefits. To be clear, I am not here to defend the use of additives such as “Mega Purple” especially when they are used to hide deficiencies in bulk production wines, but in the interest of science I try to keep an open mind.

Native vs. commercial yeasts

Though there are no universally observed definitions of natural wine, it is usually agreed that they should be fermented on native yeasts rather than inoculated with commercial strains. There isn’t much published on the composition of wines fermented on native yeasts, but there is an interesting study from Spain suggesting that the choice of yeast used in fermentation affects the diversity of natural strains in the surrounding vineyards.[1] Looking at ancient vineyards managed with organic practices, the results were opposite of what you might expect: the commercial yeast had no effect, while native yeasts reduced diversity. Conventionally managed vineyards actually had higher biodiversity.

Mega Purple

If there is an additive emblematic of the controversies of commercial wine production, it is certainly Mega Purple. Andy Perdue called it “an insidious additive that can ruin wine.” Made from a highly pigmented grape called Rubired, Mega Purple is a concentrate that adds depth of color to wine, increasing the perception of quality. No one admits to using it, but sales are reportedly robust. I will leave the question of its impact on quality to the pros, but in terms of Mega Purple’s effects on health I think it is possibly a plus. Why? Mega Purple is essentially a purified dose of anthocyanins, the antioxidant polyphenols to which many of the health benefits of wine are attributed. Without specific data though, we can’t really say whether it is a good thing in terms of health effects or not.

 Oak is no joke

Neil Shay Ph.D., Professor of Food and Nutrition Science at Oregon State University, has been investigating oak molecules found in barrel aged wine. He has found impressive properties, including for example a study where he observed that they counter the adverse effects of a high fat diet in an animal model. Where does one get the material to do such a study? Look for a “finishing and cellaring” tannin in your winemaker’s supply catalogue, where you’ll find 100% toasted French oak in powder form, intended to be added as a shortcut to time in expensive barrels.

A funny thing about a fungicide

Copper sulfate, sometimes called Bluestone, has long been used as a natural fungicide in vineyards. (Combine it with calcium hydroxide and you have “Bordeaux mixture.”)   It has been largely replaced with a fungicide called Tebuconazole, which although considered safe by the U.S. Food and Drug Administration, is listed by the World Health Organization as “slightly hazardous.” A study from the Czech Republic suggests that Tebuconazole actually preserves the antioxidant properties of resveratrol, by preventing it from binding with copper.[2]

Where next?

The more than 70 approved wine additives are just the start. Ozone (improves aromatics), pulsed electric fields (better extraction of phenolics), bioengineered yeast (reduces biogenic amines that cause headaches and allergies) and a range of treatments are available. Ultimately the best test is a clinical trial, and I have found only one: Comparing natural and conventional wines standardized to the same alcohol intake, a triple blinded study found that blood alcohol levels reached a higher and earlier peak with the conventional wines.[3] This was attributed to different amino acids and antioxidants, though the exact reason was not known for certain.

I am eager to try more natural wines, and some of my favorite producers have already gone organic or biodynamic. But it comes at a cost, and if it takes a little tweaking to make less expensive wines accessible to more people, we shouldn’t assume that it is all bad.

[1] de Celis M, Ruiz J, Martín-Santamaría M, Alonso A, Marquina D, Navascués E, Gómez-Flechoso MÁ, Belda I, Santos A.Diversity of Saccharomyces cerevisiae yeasts associated to spontaneous and inoculated fermenting grapes from Spanish vineyards. Lett Appl Microbiol. 2019 Jun;68(6):580-588.

[2]  Jaklová Dytrtová J, Straka M, Bělonožníková 3, Jakl M, Ryšlavá H. Does resveratrol retain its antioxidative properties in wine? Redox behaviour of resveratrol in the presence of Cu(II) and tebuconazole. Food Chem. 2018 Oct 1;262:221-225.

[3] Ferrero FF, Fadda M, De Carli L, Barbetta M, Sethi R, Pezzana A. Vive la Difference! The Effects of Natural and Conventional Wines on Blood Alcohol Concentrations: A Randomized, Triple-Blind, Controlled Study. Nutrients. 2019 Apr 30;11(5).

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