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Research from Thailand's Mahidol University has found that black sesame seed can significantly reduce blood pressure among men and women.
The research tested 30 men and women with an average age of 50 years old. They were considered 'pre-hypertensive' as their blood pressure levels were high but not yet high enough to be prescribed medication.
The patients' blood pressures were taken before and after the four week study. During the four weeks, the patients did not take any medications or dietary supplements.
The volunteers were divided into two groups. One group was given six placebo capsules per day, and the other group was given six capsules of 420 milligrams of black sesame seed meal. Each person in the sesame seed group was given a total of 2,520 milligrams (2.5 grams) per day.
According to the USDA, a tablespoon of sesame seeds weighs about nine grams. This would mean that the subjects were given a little less than a quarter tablespoon per day.
The research found the sesame seed meal significantly decreased the blood pressure among the treated group. Their average systolic blood pressure after the four weeks was 121 mmHg, while the average blood pressure of the placebo group was 129 mmHg.
The sesame seed group also showed decreased levels of malondialdehyde and increases in their blood vitamin E levels.
Malondialdehyde is an indicator of the amount of lipid peroxidation taking place within the bloodstream. As other research has shown, lipid peroxidation is linked to the blood vessel damage seen in atherosclerosis. This is a relationship of free radical oxidation. When low-density lipoproteins are oxidized, they can damage blood vessels because they effectively steal electrons from blood vessel wall cells.
Conversely, higher vitamin E levels are typically linked with lower lipid peroxidation because vitamin E is an antioxidant.
Black sesame contains tocopherols and antioxidants
The researchers analyzed the black sesame seed meal, and it was found to contain 105 micrograms per gram of tocopherols – primarily gamma tocopherol. By the way, this is a different configuration of synthetic vitamin E found in most supplements - rac-α-tocopheryl acetate – referred also as alpha-tocopherol.
The main medicinal constituents of black sesame seed include sesamol, sesamin and sesamolin, which are known to be antioxidants. They also contain catechins, known for their anticancer properties.
The black sesame seed and white sesame seed are different varieties of the same species, Sesamum indicum. The black seed is grown primarily in Southeast Asia.
Is white sesame seed as therapeutic as black sesame seed?
This is a good question for those of us in Western countries where the white sesame seed prevails. In 2005, researchers from Memorial University of Newfoundland investigated and compared the properties between black and white sesame seeds.
They tested both the antioxidant capacity of the two and their ability to inhibit LDL oxidation (lipid peroxidation). The researchers found that black seed's antioxidant capacity far exceeded that of white sesame seeds. The assay found black seeds scored 65.9 on the Trolox equivalent antioxidant assay while white seeds scored only 4.4.
This means black seeds have about fifteen times the antioxidant capacity as black seeds do. This makes sense, given the pigmentation difference between the two. Typically foods with greater color pigmentation will have higher antioxidation capacity.
However, the lipid peroxidation inhibition levels between the two were closer, but black seeds still scored higher. The black seeds inhibited LDL-oxidation by 96.7% while the white seeds inhibited LDL-oxidation by 84.6%.
This means that white sesame seeds have a significant ability to inhibit LDL-oxidation, but just not as much as black seeds do.
By the way, this comparison between black and white seeds also confirms what the Thailand clinical study found – that black seed can significantly reduce high blood pressure by reducing lipid peroxidation and subsequent artery damage.
Wichitsranoi J, Weerapreeyakul N, Boonsiri P, Settasatian C, Settasatian N, Komanasin N, Sirijaichingkul S, Teerajetgul Y, Rangkadilok N, Leelayuwat N. Antihypertensive and antioxidant effects of dietary black sesame meal in pre-hypertensive humans. Nutr J. 2011 Aug 9;10:82. doi: 10.1186/1475-2891-10-82.
Shahidi F, Liyana-Pathiranaa CM, Wall DS. Antioxidant activity of white and black sesame seeds and their hull fractions. Food Chem. Volume 99, Issue 3, 2006, Pages 478–483.