First, the researchers measured the beta-carotene
concentrations found in commercial sweet potato puree and sweet potato flour produced in their lab from fresh Covington sweet potatoes, as well as in three sweet potato bread formulations, using hexane extraction and absorption at 450 nm.
While breeding programs have met their targets of 15 [micro]g beta-carotene
equivalents/g crop, released varieties currently provide only ~5-10 [micro]g/g.
As compared to other antioxidative agents which prevent the establishment of lipid peroxidation, beta-carotene
traps free radicals and thus stop chain reaction.
Effects of alpha-tocopherol and beta-carotene
supplementation on cancer incidence and mortality: 18-year postintervention follow-up of the Alpha-tocopherol, Beta-carotene
Cancer Prevention Study.
Many oncologists are concerned about the possibility that beta-carotene
or other antioxidants might interfere with the anticancer effects of chemotherapy or radiation therapy.
The 2013 AREDS2 study found that replacing beta-carotene
with lutein plus zeaxanthin and cutting zinc (to 25 mg a day) worked just as well (with no difference in hospitalizations), and that omega-3 fats (EPA and DHA) didn't help.
The second study investigated the same outcome, but replaced high beta-carotene
tomato sauce with raw carrots.
To learn more, Agricultural Research Service plant physiologist Gene Lester and colleagues measured the beta-carotene
concentrations in orange-fleshed honeydew and cantaloupe melons grown under the same greenhouse conditions.
When the joint effects of high versus low nutrient intake were considered, the combination of high beta-carotene
or vitamin C with high magnesium was associated with increased protection against hearing loss at high frequencies.
Evidence from studies conducted in 1994 and 1996 by the National Cancer Institute indicated that high-dose beta-carotene
supplementation significantly increased the risk of heart disease and lung cancer among smokers.
and human health: A review of current research.
Further analyses revealed that smokers who took beta-carotene
supplements had a 26 percent reduction in their risk of developing cataracts compared to nonsmokers.