Betacarotene Secondary Prevention Trials

Supplementation with beta-carotene alone has not been well studied in secondary prevention. Two subgroup analyses and an ongoing trial are listed in Table 3.5.

In the ATBC trial, 1,862 men with a history of MI assigned to beta-carotene had a reduction in the risk of nonfatal MI (RR = 0.67; 95% CI, 0.44-1.02) and an increased risk of fatal CHD (RR = 1.58; 95% CI, 1.05-2.40) after 6 years of treatment. In the PHS I, 333 men with a history of chronic stable angina or coronary revascularization who were assigned to beta-carotene had a reduced risk of a major CVD event after 5 years (RR = 0.46; 95% CI, 0.24-0.85), but the effect was attenuated after 12 years (RR = 0.71; 95% CI, 0.47-1.07).55 In addition, beta-carotene supplementation was associated with a reduced risk of nonfatal MI (RR = 0.76; 95% CI, 0.36-1.60), nonfatal stroke (RR = 0.66; 95% CI, 0.28-1.58), and revascularization (RR = 0.66; 95% CI, 0.34-1.30), but it was also associated with an increased risk of CVD mortality (RR = 1.42; 95% CI, 0.72-2.80). The WACS was the only large trial that evaluated beta-carotene alone in the secondary prevention of CVD,56 and after 9.4 years, beta-carotene (50 mg every other day) had no effect on CVD outcomes (RR = 1.01; 95%CI, 0.91-1.12).48

A meta-analysis of large antioxidant trials that evaluated beta-carotene supplementation alone or in combination with other antioxidants found a small but significant increased risk of CVD death (RR = 1.10; 95% CI, 1.03-1.17) and total mortality

Table 3.5 Completed and ongoing randomized clinical trials of beta-carotene alone in the secondary prevention of cardiovascular disease (CVD)

Effect of beta-caro-

Duration of

tene supplementation.

Study

Population; Country

Agent(s)a

txb (years)

Endpoint

RR (95% CI)

Alpha-Tocopherol. Beta-

1.862 male smokers

Beta-carotene (20mg/d),

6

Major coronary event

1.11 (0.84-1.49)

Carotene Cancer

aged 50-69 years

vitamin E (50mg/d),

Nonfatal MI

0.67 (0.44-1.02)

Prevention Trial

with prior MI;

or both

CHD mortality

1.75 (1.16-2.64)

(ATBC) substudy

Finland

Physicians' Health Study

333 male physicians

Beta-carotene (50mg/d),

12

CVD mortality + MI +

0.71 (0.24-1.07)

(PHS) substudy

aged 40-84 years with angina or coronary revascularization; United States

aspirin (325 mg every other day), or both

stroke

Women's Antioxidant

8.171 female health

Beta-carotene (50 mg

9.4

MI + stroke + revascu

1.01 (0.91-1.12)

Cardiovascular Study

professionals aged

every other day).

larization + CVD

(WACS)

>45 years, with CVD or >3 coronary risk factors; United States

other antioxidant0, or a combination (2 x 2 x 2 x 2 factorial design)

mortality

" All trials were placebo controlled. b Duration of treatment equals duration of follow-up.

" Vitamin E (600IU every other day); vitamin C (500 mg daily); or combination of folic acid (2.5 mg daily), vitamin B6 (50 mg daily), and vitamin B12 (1 mg daily).

" All trials were placebo controlled. b Duration of treatment equals duration of follow-up.

" Vitamin E (600IU every other day); vitamin C (500 mg daily); or combination of folic acid (2.5 mg daily), vitamin B6 (50 mg daily), and vitamin B12 (1 mg daily).

(RR = 1.07; 95% CI, 1.02-1.11).49 In summary, beta-carotene supplementation may have more risk than benefit and cannot be routinely recommended for the primary or secondary prevention of CVD.

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