Abstract
Experimental and epidemiological evidence supports the hypothesis that oxidation of low density lipoprotein (LDL) appears to be important in mediating the atherogenicity of LDL. To test this hypothesis in humans, it will be necessary to perform intervention studies in large populations. We performed two studies to assess the effectiveness of supplementation with β-carotene and vitamin E, used alone and in combination with each other, and with vitamin C, to protect LDL from oxidation. In phase 1, after a placebo period, eight subjects were given β-carotene (60 mg/day) for 3 months, then β-carotene plus vitamin E (1,600 mg/day) for another 3 months, and then β-carotene plus vitamin E plus vitamin C (2 g/day) for 3 months. During phase 2, β-carotene and vitamin C were discontinued, and subjects took only vitamin E for 5 months. During each period, LDL samples were isolated, and measurements of susceptibility to oxidation were performed. β-Carotene levels in LDL increased nearly 20-fold, but LDL susceptibility to oxidation did not change. Addition of vitamin E increased LDL vitamin E levels nearly 2.5-fold, and this decreased LDL oxidation 30-40%. During the vitamin C supplementation period, plasma levels of β-carotene and vitamin E rose, but only β-carotene increased in LDL. However, the susceptibility of LDL to oxidation in this period was not decreased further. During phase 2, when subjects took only vitamin E, LDL susceptibility to oxidation was decreased by 50% as measured by thiobarbituric acid-reactive substances, conjugated dienes, and lipid peroxide formation as well as by macrophage degradation. Thus, long-term supplementation with large doses of vitamin E alone, but not β-carotene, conferred increased protection to LDL in in vitro assays of oxidation. These data should be useful in planning therapeutic strategies to test the antioxidant hypothesis in humans.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 590-600 |
| Number of pages | 11 |
| Journal | Arteriosclerosis, thrombosis, and vascular biology |
| Volume | 13 |
| Issue number | 4 |
| DOIs | |
| State | Published - Jan 1 1993 |
| Externally published | Yes |
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Keywords
- Antioxidants
- Atherosclerosis
- Conjugated dienes
- HDL
- LDL
- Lipid oxidation
- Macrophages
- Vitamin C
- Vitamin E
- β-carotene
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
Cite this
Effect of dietary antioxidant combinations in humans : Protection of LDL by vitamin E but not by β-carotene. / Reaven, Peter D.; Khouw, Andrew; Beltz, William F.; Parthasarathy, Sampath; Witztum, Joseph L.
In: Arteriosclerosis, thrombosis, and vascular biology, Vol. 13, No. 4, 01.01.1993, p. 590-600.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Effect of dietary antioxidant combinations in humans
T2 - Protection of LDL by vitamin E but not by β-carotene
AU - Reaven, Peter D.
AU - Khouw, Andrew
AU - Beltz, William F.
AU - Parthasarathy, Sampath
AU - Witztum, Joseph L.
PY - 1993/1/1
Y1 - 1993/1/1
N2 - Experimental and epidemiological evidence supports the hypothesis that oxidation of low density lipoprotein (LDL) appears to be important in mediating the atherogenicity of LDL. To test this hypothesis in humans, it will be necessary to perform intervention studies in large populations. We performed two studies to assess the effectiveness of supplementation with β-carotene and vitamin E, used alone and in combination with each other, and with vitamin C, to protect LDL from oxidation. In phase 1, after a placebo period, eight subjects were given β-carotene (60 mg/day) for 3 months, then β-carotene plus vitamin E (1,600 mg/day) for another 3 months, and then β-carotene plus vitamin E plus vitamin C (2 g/day) for 3 months. During phase 2, β-carotene and vitamin C were discontinued, and subjects took only vitamin E for 5 months. During each period, LDL samples were isolated, and measurements of susceptibility to oxidation were performed. β-Carotene levels in LDL increased nearly 20-fold, but LDL susceptibility to oxidation did not change. Addition of vitamin E increased LDL vitamin E levels nearly 2.5-fold, and this decreased LDL oxidation 30-40%. During the vitamin C supplementation period, plasma levels of β-carotene and vitamin E rose, but only β-carotene increased in LDL. However, the susceptibility of LDL to oxidation in this period was not decreased further. During phase 2, when subjects took only vitamin E, LDL susceptibility to oxidation was decreased by 50% as measured by thiobarbituric acid-reactive substances, conjugated dienes, and lipid peroxide formation as well as by macrophage degradation. Thus, long-term supplementation with large doses of vitamin E alone, but not β-carotene, conferred increased protection to LDL in in vitro assays of oxidation. These data should be useful in planning therapeutic strategies to test the antioxidant hypothesis in humans.
AB - Experimental and epidemiological evidence supports the hypothesis that oxidation of low density lipoprotein (LDL) appears to be important in mediating the atherogenicity of LDL. To test this hypothesis in humans, it will be necessary to perform intervention studies in large populations. We performed two studies to assess the effectiveness of supplementation with β-carotene and vitamin E, used alone and in combination with each other, and with vitamin C, to protect LDL from oxidation. In phase 1, after a placebo period, eight subjects were given β-carotene (60 mg/day) for 3 months, then β-carotene plus vitamin E (1,600 mg/day) for another 3 months, and then β-carotene plus vitamin E plus vitamin C (2 g/day) for 3 months. During phase 2, β-carotene and vitamin C were discontinued, and subjects took only vitamin E for 5 months. During each period, LDL samples were isolated, and measurements of susceptibility to oxidation were performed. β-Carotene levels in LDL increased nearly 20-fold, but LDL susceptibility to oxidation did not change. Addition of vitamin E increased LDL vitamin E levels nearly 2.5-fold, and this decreased LDL oxidation 30-40%. During the vitamin C supplementation period, plasma levels of β-carotene and vitamin E rose, but only β-carotene increased in LDL. However, the susceptibility of LDL to oxidation in this period was not decreased further. During phase 2, when subjects took only vitamin E, LDL susceptibility to oxidation was decreased by 50% as measured by thiobarbituric acid-reactive substances, conjugated dienes, and lipid peroxide formation as well as by macrophage degradation. Thus, long-term supplementation with large doses of vitamin E alone, but not β-carotene, conferred increased protection to LDL in in vitro assays of oxidation. These data should be useful in planning therapeutic strategies to test the antioxidant hypothesis in humans.
KW - Antioxidants
KW - Atherosclerosis
KW - Conjugated dienes
KW - HDL
KW - LDL
KW - Lipid oxidation
KW - Macrophages
KW - Vitamin C
KW - Vitamin E
KW - β-carotene
UR - http://www.scopus.com/inward/record.url?scp=0027411988&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0027411988&partnerID=8YFLogxK
U2 - 10.1161/01.ATV.13.4.590
DO - 10.1161/01.ATV.13.4.590
M3 - Article
C2 - 8466894
AN - SCOPUS:0027411988
VL - 13
SP - 590
EP - 600
JO - Arteriosclerosis, Thrombosis, and Vascular Biology
JF - Arteriosclerosis, Thrombosis, and Vascular Biology
SN - 1079-5642
IS - 4
ER -