Minor Component of Vitamin E, Tocotrienols, May Enhance Aging Immune Function

by | Jun 18, 2010 | 2010, Immune Health, Tocotrienols

Written by Susan Sweeny Johnson, PhD, Biochem. Tocotrienols enabled the T cells of older mice to multiply more rapidly. 

The major component of vitamin E, alpha-tocopherol, has been extensively studied, although some of its physiological benefits are hotly debated. Natural vitamin E, however, has a variety of other forms of tocopherols and tocotrienols which are only beginning to be examined (1). Some initial studies suggest that tocotrienols may have unique cholesterol-managing (2-4) and neuroprotective properties (5-7).

Researchers have previously demonstrated in their laboratory that alpha-tocopherol increases T-cell immune response, particularly in the elderly (8). In a new study, they looked at the effect of tocotrienol (T3) dietary supplementation on the ability of lymphocytes (specifically t-cells) to reproduce in both young and old mice. The test groups received diets that included 393 mg of T3* in addition to 107 mg per kg of food of alpha-tocopherol,  the control groups received diets with 107 mg/ kg alpha-tocopherol only. The feedings were conducted for 6 weeks, at which time the spleen cells which contain abundant T-cells were removed and characterized.

Harvested T-cells from the spleens of test and control animals were examined for their ability to multiply. As expected overall, the T-cells from old mice were not as hearty as those from young mice and did not multiply as rapidly. Feeding T3 did not increase the multiplication rate of young mice T-cells but did significantly increase the multiplication of T-cells from older mice. The lymphocyte profile (the types of immune cells and their relative abundance) in the spleens did not vary between the control and test groups.

In addition, the researchers examined the effects of three individual forms of T3: alpha, gamma and delta, on the multiplication rate of T-cells in vitro. Again, incubation with each form of tocotrienol increased the ability of T-cells from older mice to multiply but had little effect on T-cells from young mice.

The researchers also examined the different interleukins and prostaglandins produced by all the T-cell fractions in order to determine a mechanism for tocopherol and tocotrienol enhancement of immune response. Results suggest a different mechanism for tocotrienols than for alpha-tocopherol.

In conclusion, whole, natural vitamin E complex appears to have components, for example tocotrienols, that can help aging immune systems beyond the benefits of isolated alpha-tocopherol. Further study of different vitamin E components in humans is warranted.

* These diets of 500 mg/kg food alpha-tocopherol per day translate to a dose roughly equivalent to 200 mg/d for humans. The test groups received tocotrienols translating to 233 mg/day for a person of 70 kg (9). One mg of alpha-tocopherol is equivalent to 1.49 IU (International Units) of activity, so 200 mg = 298 IU. There are no IU equivalents for tocotrienols.

Source: Ren, Zhihong, et al. “Dietary supplementation with tocotrienols enhances immune function in C57BL/6 mice.” The Journal of nutrition 140.7 (2010): 1335-1341.

© 2010 American Society for Nutrition.

Posted June 18, 2010.

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