マンスリーコラムMonyhly column

JBA Article: Hydroxyl Radical v15 May 2026

The Hydroxyl Radical and Blackcurrants - ‘the Sword and the Shield’

Some years ago, a very good friend of mine, a well-known biological scientist, submitted a paper on the role of antioxidants in human biology. The paper was rejected on the basis that he had not explained why oxidation was also a necessary part of human biology. He altered his paper to include a reference to the necessity of oxidation. For example: our white blood cells intentionally generate free radicals to destroy invading bacteria and viruses; in controlled amounts free radicals act as ‘cell signallers’, as messengers that help our cells react to stress. My friend’s paper was published as it not only promoted the benefits of antioxidants but also put that benefit in perspective: that not all radicals are bad.

The exception is the hydroxyl radical (*OH). It is a by-product of the process in each cell of turning food into energy. That process can be affected by such things as ‘urban stress’, ‘inappropriate diets’ and ‘environmental degradation’. I know that is a sweeping catch-all of conditions but it is today’s reality for many.

Think of the hydroxyl radical as a sword, a sword that lashes out wildly and does damage within the cells in your body. The *OH has an electron missing and is chemically unstable, so it steals an electron from anything nearby. A molecular thief that steals electrons and in so doing creates oxidative stress.The result can be: Lipid peroxidation - turning cell membranes rancid and leaky; DNA damage - altering genetics codes which can lead to mutation; Protein degradation - breaking down the structural integrity of tissues and enzymes.

As you can see, that is one nasty ‘sword’ wildly lashing out inside your body. Unlike some other free radicals, our bodies don't have a specific enzyme to neutralize the *OH directly. We are largely dependent on the antioxidants we consume to act as a ‘shield’. And fortunately, over the millenia, our bodies developed to seek out and enjoy foods that had such antioxidant values.

So lets see how and why the blackcurrant seems very well endowed to be such a food: an effective shield to the ‘deranged sword’!

Much research, over the last 20 years especially, has shown the blackcurrants to be a biological safeguard. Blackcurrants have two special antioxidant anthocyanins, two shields, that are match fit for *OH’s sword attacks: delphinidin-3-rutinoside and cyaninidin-3-rutinoside.

Research establishing this was done with Blackcurrant Extract (BCE) in powdered form. So I’ll refer to BCE as I talk about the blackcurrant benefits.

The BCE anthocyanins are bioavailable:they enter the blood stream and tissues where the *OH does its damage. Anthocyanins are remarkably generous: they give up their own electrons to the *OH before it can strike your DNA or cell membranes.

But there is another value in BCE: it has been shown to stimulate your body’s own internal antioxidant production (like glutathione) , essentially upgrading your internal security system.

In consuming BCE you are not just eating fruit, you are deploying a sophisticated molecular defense: the shield. The perfect counter-narrative to what could be the body’s biggest baddie: the hydroxyl radical wild sword. The blackcurrant extract represents the resilience and restoration provided by nature: bodily harmony for an increasingly hostile environment.

As you know, I have a marketing background and as I said at the start of this article: I am neither scientist nor medical professional. But I have used my own language to explain in summary a very complex matter. Below is a list of science references to support this article.

Yoroshiku onegaishimasu,

Bill Floyd
Advisor,
Japan Blackcurrant Association.

Research summary provided by AI:

• The literature supporting the biological impact of the hydroxyl radical and the specific efficacy of Blackcurrant Extract (BCE) is robust, spanning biochemistry, cell biology, and human clinical trials.
• Below is a summary of the peer-reviewed evidence that substantiates the dual nature of these molecules.
• ### 1. The Hydroxyl Radical: Biology's Most Reactive Threat Research identifies the hydroxyl radical (\cdot OH) as the most volatile of all reactive oxygen species (ROS). Because it possesses an unpaired electron, it is chemically unstable and highly reactive toward biological macromolecules (Das, n.d.).
• * **Mechanism of Damage:** The radical initiates **lipid peroxidation**, which targets the double bonds in polyunsaturated fatty acids found in cell membranes (Das, n.d.). This process produces toxic byproducts like malondialdehyde (MDA), which are markers of systemic oxidative stress (Das, n.d.).
• * **DNA and Protein Oxidation:** Hydroxyl radicals directly cause DNA strand breaks and protein oxidation, which converts amino acids into aldehydes and carboxylic acids, compromising cellular function (Das, n.d.).
• * **Radical’s Good values: ** While predominantly harmful, ROS (including radicals) are recognized as essential messengers in **cell signaling** and the body's immune response, provided they are maintained in a state of redox homeostasis (Garcia-Llorens, n.d.).
• ### 2. BCE as a Molecular Shield Blackcurrant Extract is highly regarded in nutritional science due to its concentrated profile of anthocyanins, particularly **delphinidin-3-rutinoside** and **cyanidin-3-rutinoside** (Khoo et al., 2017).
• * **Radical Scavenging Efficiency:** Anthocyanins neutralize free radicals through two primary mechanisms: **Hydrogen Atom Transfer (HAT)** and **Single-Electron Transfer (SET)** (Sadowska-Bartosz & Bartosz, 2024). Delphinidin is noted for having the highest number of hydroxyl groups on its B-ring, which provides superior intracellular radical scavenging compared to other anthocyanins (Cook et al., 2025).
• * **Internal Defense Upgrades:** Beyond direct scavenging, BCE has been shown to activate the **NRF2 pathway** (Cao et al., 2021). NRF2 is a transcription factor that regulates the body’s internal antioxidant defense genes, such as glutathione S-transferase and heme oxygenase 1, effectively "pre-arming" cells against oxidative stress (Cao et al., 2021).
• * **Clinical Evidence:** Human studies have demonstrated that consuming New Zealand blackcurrant extract prior to high-intensity exercise—a state that naturally spikes radical production—assists in recovery from oxidative stress and maintains better circulating antioxidant status (Hurst et al., 2017, as cited in Gonzalez, n.d.; Willems & Blacker, 2022).
• ### 3. Bioavailability and Stability For BCE to be effective, its active compounds must survive digestion and enter the bloodstream.
• * **Digestive Stability:** While anthocyanins can be sensitive to pH changes, research using simulated gastrointestinal models suggests that a significant portion of blackcurrant anthocyanins remain stable enough to be absorbed (Uzunović & Vranić, 2008).
• * **In-Vivo Impact:** Even though serum uptake of intact anthocyanins can appear low (often <1%), their metabolites and their ability to trigger internal cellular responses (like the NRF2 pathway) are what drive their meaningful physiological effects (Willems & Blacker, 2022; Cao et al., 2021).

### References

• Cao, L., Park, Y., Lee, S.,  &Kim, D.-O. (2021). Extraction, identification, and health benefits of anthocyanins in blackcurrants (Ribes nigrum L.). *Applied Sciences*, *11*(4), 1863.
  https://doi.org/10.3390/app11041863
Cited by: 60
• Cook, M. D., Shan, Y.,  &Willems, M. E. T. (2025). Effects of New Zealand black currant extract on exercising substrate utilization and postexercise blood pressure in men and women. *International Journal of Sport Nutrition and Exercise Metabolism*, *35*(2), 150-161.
  https://doi.org/10.1123/ijsnem.2024-0108
• Cited by: 3
  Das, T. K. (n.d.). Oxidative stress gated by Fenton and Haber Weiss reactions and its association with Alzheimer's disease. *Annals of Military and Health Sciences Research*..
• Cited by: 271
  Garcia-Llorens, G. (n.d.). Oxidative stress fundamentals: Unraveling the pathophysiological
  role of redox imbalance in non-communicable diseases. *Applied Sciences*.
• Cited by: 26
  Khoo, H. E., Azlan, A., Tang, S. T.,  &Lim, S. M. (2017). Anthocyanidins and anthocyanins: Colored pigments as food, pharmaceutical ingredients, and the potential health benefits.
  *Food  &Nutrition Research*, *61*(1), 1361779.
  https://doi.org/10.1080/16546628.2017.1361779
• Cited by: 3930
  Sadowska-Bartosz, I.,  &Bartosz, G. (2024). Antioxidant activity of anthocyanins and anthocyanidins: A critical review. *International Journal of Molecular Sciences*, *25*(22),12001.
  https://doi.org/10.3390/ijms252212001
• Cited by: 149
  Uzunović, A.,  &Vranić, E. (2008). Stability of anthocyanins from commercial black currant juice under simulated gastrointestinal digestion. *Bosnian Journal of Basic Medical Sciences*, *8*(3), 254-258. https://doi.org/10.17305/bjbms.2008.2928
• Cited by: 23
  Willems, M. E. T.,  &Blacker, S. D. (2022). Anthocyanin-rich supplementation: Emerging evidence of strong potential for sport and exercise nutrition. *Frontiers in Nutrition*, *9*,864323.
  https://doi.org/10.3389/fnut.2022.864323
• Cited by: 25

Research summary ends.