The limitations of vitamin E and the search for alternative antioxidants

By Vincent Jacquier, Category specialist Polyphenols

Research has shown that only a small fraction of supplemented vitamin E is absorbed and utilized by the body. In pigs, vitamin E’s bioavailability has been estimated to be as low as 5%. Vitamin E also has a narrow antioxidant scope. It doesn’t provide protection against oxidative damage to proteins and its consequences. Moreover, high doses of vitamin E have an inconsistent impact on animal performance. Given these challenges, there is a growing need for alternative antioxidants that can provide a similar, or even better, protection against oxidative stress.

Vitamin E has been widely recognized as an essential antioxidant in animal nutrition. Its primary function is to protect polyunsaturated fatty acids (PUFAs) within cell membranes from oxidation, preventing the formation of lipid peroxides that can damage cells and tissues. This ability to stabilize lipids has made vitamin E a staple in livestock diets, particularly in pigs and poultry, where meat quality is of significant economic importance. However, despite its widespread use, there are growing concerns regarding the real effectiveness of vitamin E, particularly when supplemented at high levels.

One of the main limitations of vitamin E is its low bio-availability. The most commonly used form in animal nutrition is tocopheryl acetate, which must be hydrolyzed in the intestine before it becomes biologically active. Research has shown that only a small fraction of supplemented vitamin E is absorbed and utilized by the body. In pigs, vitamin E’s bio-availability has been estimated to be as low as 5%, which means that the majority of what is provided in the diet is not effectively used. This low absorption rate is further complicated by its short plasma half-life—studies indicate that vitamin E has a half-life of approximately 2.5 hours in pigs, which is significantly shorter than the 24–72 hours previously assumed. This suggests that vitamin E levels in the bloodstream fluctuate rapidly, requiring frequent supplementation to maintain adequate protection against oxidative stress.

Another limitation of vitamin E is its narrow antioxidant scope. Because vitamin E is a fat-soluble compound, it primarily acts within lipid membranes. While this is beneficial for protecting PUFAs from oxidation, it does little to prevent oxidative damage to proteins or DNA, which are also highly susceptible to free radical attacks. Oxidative damage to proteins can impair cellular metabolism, reduce enzyme function, and compromise immune responses, yet vitamin E provides little protection in these areas. In contrast, alternative antioxidants—such as polyphenols—offer broader protection by functioning in both lipid and aqueous environments.

A further concern is the inconsistent impact of high vitamin E doses on animal performance. While vitamin E is frequently recommended for improving growth, immune function, and meat quality, meta-analyses of dose-response studies in multiple species have failed to show a clear correlation between higher vitamin E levels and enhanced performance. In some regions, extremely high doses of vitamin E are routinely used, yet the scientific justification for this practice remains unclear. The variation in vitamin E recommendations across different countries further highlights the uncertainty surrounding its optimal dosage. In Latin countries, recommended levels tend to be closer to NRC guidelines, whereas in regions such as Belgium, Italy, and Russia, significantly higher levels are common. In other countries, such as the United States, intermediate levels are used. This lack of consistency raises important questions about whether high-dose vitamin E supplementation is truly necessary or if alternative strategies could provide more effective antioxidant protection.

Polyphenol-based products as alternative antioxidants: insights from Vitanox in swine

Given these challenges, there is a growing interest in identifying alternative antioxidants that can provide a similar, or even better, protection against oxidative stress. One of the most promising alternatives is polyphenols, a diverse group of plant-derived compounds that have demonstrated strong antioxidant potential. Unlike vitamin E, polyphenols can function across multiple cellular compartments, offering protection to lipids, proteins, and DNA alike. Additionally, some polyphenols have been shown to exert anti-inflammatory and gut-health-promoting effects, making them valuable tools for improving overall animal resilience. For example, the polyphenol-based product Vitanox has demonstrated synergy with vitamin E, leading to improved health and feed conversion (Table 1). Partial replacement also maintains an equivalent blood antioxidant status (Table 2).

Additional information on the development and mode of action of Vitanox can be found in our Vitanox White Paper, which is available upon request via marcom.emea@agrifirm.com.