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Life Extension Magazine

LE Magazine February 2005
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Do Your Antioxidants Suppress Enough Free Radicals?

By Jim English

In 1991, researchers in Kyoto, Japan, demonstrated that sesamin lignans effectively inhibit delta-5 desaturase, the enzyme responsible for converting DGLA into highly inflammatory arachidonic acid.35

This anti-inflammatory effect was also noted in animals that were fed linseed oil and sesame lignans. Linseed oil is a source of DGLA. Linseed and sesame lowered blood levels of tumor necrosis factor-alpha and PGE-2, two inflammatory mediators. Feeding rats sesame led to significant accumulations of DGLA in the tissues and reduced inflammation caused by tumor necrosis factor-alpha and PGE-2.36

An undesirable side effect of supplementing with highly polyunsaturated fats is increased production of free radicals. The addition of sesame lignans to fish oil can help lower lipid peroxidation rates caused by the fish oil. Sesame suppresses the formation of lipid peroxides from docosahexaenoic acid (DHA), which is highly susceptible to oxidation but is also one of the primary omega-3 fatty acids in fish oil that block inflammation. The combination of sesame with fish oil thus helps to enhance the fish oil’s anti-inflammatory effects by protecting it from lipid peroxidation.37

Sesame Lignans May Support Weight Loss

Optimizing the liver’s oxidation of fatty acids has been proposed to help promote fat loss.38 Numerous studies suggest that sesame lignans may aid in weight loss by enhancing fatty acid oxidation in liver tissues. In a study of rats, the addition of sesamin, one of the most abundant sesame lignans, increased the activity of numerous fatty acid oxidation enzymes.39 While this effect was observed in all groups of rats given various dietary oils, it was especially pronounced in rats consuming fish oil.39 Fish oil appears to act synergistically with sesame lignans to promote fat burning.

Conjugated linoleic acid (CLA) is a fatty acid known to promote weight loss. In a study in rats, the addition of sesamin to CLA promoted even greater weight loss, as measured by a reduction in adipose tissue weight.40 Sesame lignans thus appear to have a synergistic effect, enhancing the benefits of fish oil and CLA in promoting optimal fat burning and healthy weight.

New Study Confirms Sesame’s Synergistic Effects

In response to these remarkable published studies on sesame, Life Extension conducted a clinical trial to see what would happen to people who took supplements containing gamma tocopherol and sesame lignans.

To establish a baseline, three markers of oxidative stress and inflammation—dityrosine, isoprostane, and PLGF-1—were measured in the blood of a group of human test subjects. The group was then divided into two subgroups, with one subgroup given gamma tocopherol plus tocotrienols and the other receiving the same amount of gamma tocopherol plus sesame lignans.

The dityrosine marker measures serum levels of deep-tissue protein oxidation caused by the peroxynitrite radical reacting with tyrosine, an amino acid found in all human proteins. Tyrosine is the amino acid most readily attacked by the pero-xynitrite radical, an extremely powerful free radical that has been implicated in a host of disorders. Gamma tocopherol is the only tocopherol that reacts with, or traps, the peroxynitrite radical to any appreciable degree. Compared to the gamma tocopherol-tocotrienol group, those taking gamma tocopherol plus sesame showed a 45% reduction in serum dityrosine oxidation levels after two weeks of supplementation.

A three-dimensional spiral CT scan of carotid atherosclerosis.

The isoprostane marker measures the amount of cell membrane damage caused by free radicals. Also called lipid peroxidation, cell membrane damage involves a free radical chain reaction of cell membrane fatty acids. Normally, lipid peroxidation results in one free radical destroying 8 to 10 normal molecules before being quenched. Supplementing with vitamin E products can limit this destruction to one or two molecules rather than the normal 8-10 molecules that occurs without supplementation. Compared to the gamma tocopherol-tocotrienol group, those taking gamma tocopherol plus sesame showed a 22% reduction in serum isoprostane levels after two weeks of supplementation.

The PLGF-1 marker is an extremely sensitive new test for atherosclerotic risk in humans. PLGF-1 stands for “placental growth factor” because it was originally identified in the placenta. For adults, however, high levels of PLGF-1 are indicative of atherosclerotic lesions. PLGF-1 stimulates vascular smooth muscle cell growth, recruits macrophages into atherosclerotic lesions, up-regulates production of tumor necrosis factor-alpha and stimulates undesirable angiogenesis. In the animal model, inhibition of PLGF-1 suppressed both atherosclerotic plaque growth and arterial wall inflammatory reactions. PLGF-1 may be considered a marker for the presence of unstable arterial wall plaque. Compared to the gamma tocopherol-tocotrienol group, those taking gamma tocopherol plus sesame showed an 11.5% reduction in serum PLGF-1 levels after two weeks of supplementation.

Considering that the subjects in this experiment were a healthy group to begin with—with baseline PLGF-1 levels that were already in the lowest percentage quartile—the 11.5% reduction recorded in the gamma tocopherol plus sesame group was impressive. Presumably, those with arterial wall dysfunction, who normally have high PLGF-1 levels, would derive even greater benefit from supplements that lowered this very sensitive inflammatory marker. The same would hold true for aging adults whose baseline oxidative stress levels are very high compared to this healthy group of test subjects.

Based on these three advanced measurements of free radical and inflammatory damage, gamma tocopherol plus sesame lignans is on average 25% more effective in reducing three biomarkers of oxidative stress and inflammation than the more expensive gamma tocopherol plus tocotrienols.

Spiral CT scan showing atherosclerosis of left carotid artery.

What is so impressive about this recent trial is that unlike previous studies, the effects of sesame were not compared to a placebo or control group. Instead, this human study compared the effects of supplementing with low-cost sesame to those of taking very expensive tocotrienols. The tocotrienols are considered nature’s most potent natural antioxidants. Yet in this study, sesame was found to work 25% better than the tocotrienols.

Summary

Sesame and its lignans have been shown to possess multiple health benefits, both alone and in synergistic combination with other compounds, including gamma tocopherol and fish oil. Sesame lignans help to increase tissue and serum levels of biological antioxidants that have been strongly correlated with improved health in mammals and humans.

Sesame lignans have also demonstrated anti-inflammatory benefits and block free radical lipid peroxidation in fish oil supplements to suppress inflammation. Lignans are powerful inhibitors of LDL oxidation, effectively reducing atherogenic processes. Lastly, lignans are potent stimulators of fatty acid oxidation, one of the key processes involved in weight control.

By influencing biochemical processes in the body, sesame and its lignans promise to help reduce risk for many of today’s most common diseases, including heart disease, obesity, and inflammatory disorders.

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