|Date: September 15, 2004||HC# 030443-264|
Re: Lycopene in Blood Associated with Reduced Incidence of Cardiovascular Disease in Women
Sesso H, Buring J, Norkus P, Gaziano JM. Plasma lycopene, other carotenoids, and retinol and the risk of cardiovascular disease in women. American Journal of Clinical Nutrition. 2004;79:47-53.
There is growing evidence that lycopene, a carotenoid without provitamin A activity, which is found in high concentrations in a small number of plant foods (tomato, watermelon, pink grapefruit, papaya, and apricot), has significant antioxidant potential in vitro. Although most research on lycopene has focused on its possible role in reducing the risk of prostate cancer, limited epidemiologic data support a preventive effect of lycopene against cardiovascular disease (CVD). It has been suggested that lycopene may have a cholesterol synthesis-inhibiting effect that could enhance LDL (low-density lipoprotein) degradation. More than 80% of the lycopene intake in the American diet comes from the consumption of tomato products, including ketchup, tomato juice, and tomato sauces.
The current study evaluated baseline concentrations of plasma lycopene, other carotenoids, and retinol in middle-aged and elderly women in the Women's Health Study (WHS), who were initially free of CVD, to examine their relation with the subsequent risk of CVD. The WHS is an ongoing randomized, double-blind, placebo-controlled 2 X 2 factorial trial of the relation between low-dose aspirin and vitamin E and the primary prevention of CVD and cancer.
A prospective, nested, case-control design was used to identify 483 case-control pairs of WHS participants. Cases included women who provided baseline blood samples and subsequently experienced a cardiovascular event, defined as CVD death, nonfatal MI, nonfatal stroke, percutaneous transluminal coronary angioplasty, coronary artery bypass graft, or angina pectoris. Study physicians conducted blinded reviews of all cases. Each case of CVD was matched with a control subject according to age, smoking status, and follow up time.
Women with concentrations of plasma lycopene of at least 16.5 mcg/dL had a possible 34% reduction in total CVD compared with those in the lowest quartile, after adjustment for major lifestyle, clinical, and dietary risk factors. The magnitude of the effect was stronger after women with angina were excluded.
In relating plasma lycopene levels to other carotenoids, lycopene was most closely correlated with plasma beta-carotene levels, followed by beta-cryptoxanthin, lutein/zeaxanthin, alpha-carotene, and retinol. Increasing quartiles of plasma retinol, beta-cryptoxanthin, and lutein/zeaxanthin were not associated with the risk of CVD.
Correlations among tomato products with plasma lycopene were highest for tomato sauce, which is consistent with the lipophilic properties of lycopene that require the simultaneous ingestion of fats for optimal absorption. No other dietary factors were strongly associated with plasma lycopene. Therefore, beyond modest effects for tomato sauce, no clear dietary pattern emerged which greatly affected plasma lycopene concentrations. Other factors related to lycopene absorption and metabolism may also confound the association between plasma and dietary lycopene.
The researchers conclude that higher plasma lycopene concentrations may be associated with a lower risk of CVD in middle-aged and elderly women. However, they also pointed out that plasma lycopene may simply be a marker for another dietary or nutritional component that travels with lycopene in foods. Further research on the potential mechanistic actions of lycopene in the prevention of CVD and other chronic diseases is warranted.
-Densie Webb, PhD