Another major class of plant-borne antioxidants is the carotenoids… a family that includes beta-carotene, which gives orange carrots and red-yellow peppers their bright colors.
The carotenoid clan includes the yellowish antioxidants in leafy greens like spinach, chard, and kale, called xanthophylls (zan-tho-fills).
The xanthophylls we get from leafy greens (lutein and zeaxanthin) concentrate in the retina, where they help perform and protect key vision functions.
But one long-overlooked, highly promising member of the xanthophyll family is found only in red- and orange-hued fish and shellfish.
We’re talking about astaxanthin, which is produced by certain kinds of algae, and lends its red-orange hue to the small crustaceans that eat them, and to wild Pacific salmon, which feed upon those tiny shellfish.
Wild Pacific salmon are the richest human food source of astaxanthin by far, with all five commercial species—sockeye (red), king (chinook), silver (coho), chum (keta), and pink—providing ample amounts.
Because sockeye salmon feed mostly on small astaxanthin-rich crustaceans, these aptly nicknamed “red” salmon provide more astaxanthin than the other species do.
As we'll explain (see “Astaxanthin in wild and farmed salmon”, below), farmed and wild salmon contain different kinds of astaxanthin.
And wild sockeye has as much as four times as much of the compound, all of it occuring in the natural form used in the new trial and prior studies.
Clinical trial adds to astaxanthin's cardiovascular promise
Past research has found that supplemental astaxanthin can lower blood pressure and artery damage in rats, while human studies indicate that supplemental astaxanthin can lower blood pressure, ease blood flow, and reduce dangerous oxidation of cholesterol.
Now the recently published results of a Japanese clinical study link astaxanthin to improvements in key markers for cardiovascular health... and they support earlier indications that it boosts a hormone that deters accumulation of highly unhealthful belly fat (Yoshida H et al. 2009).
Researchers at Jikei University conducted a three-month, placebo-controlled trial in 61 people aged 25-60, with normal-to-high triglyceride levels (120-200mg/dl).
They were assigned to take capsules that contained either no astaxanthin at all (placebo pills) or delivered astaxanthin doses of 6mg, 12mg, or 18mg per day.
Compared with the placebo group, blood tests showed that the people who took 12mg or 18mg per day showed significantly reduced triglyceride levels, while those who took 6mg or 12mg per day enjoyed significantly higher levels of “good” HDL cholesterol.
In addition, blood levels of adiponectin—a hormone that discourages accumulation of unhealthful belly fat—rose in the people who took 12mg or 18mg of astaxanthin per day.
As the authors wrote, “This first-ever randomized, placebo-controlled human study suggests that astaxanthin consumption ameliorates [improves] triglyceride and HDL-cholesterol in correlation [tandem] with increased adiponectin [levels] ...”
Astaxanthin in wild and farmed salmon: Not created equal
Most of the studies conducted to date have used a supplemental astaxanthin product extracted from fresh-water algae (Haematacoccus pluvialis).
Those supplements contain the same form of astaxanthin found in wild salmon, so it seems reasonable to presume that equivalent intakes, whether from supplements or wild salmon, would yield similar bodily effects.
If anything, salmon should be the superior source because it provides astaxanthin as part of a full package of synergistic nutrients—omega-3s, vitamin D, and astaxanthin—in a combined abundance found in no other food.
Farmed salmon get astaxanthin as a feed additive, both because consumers will not buy white- or grey-fleshed salmon, and because astaxanthin is essential for salmon’s growth and overall health.
A minority of farmed salmon get chow that contains the natural form derived from algae, but most farms feed their fish the cheaper synthetic astaxanthin made from petrochemicals.
Astaxanthin comes in various forms, and chemists can tell farmed salmon from wild salmon by looking for the unnatural forms (isomers) created when astaxanthin is synthesized from petroleum.
To date, there is no evidence that the unnatural forms of astaxanthin in farmed salmon deliver health benefits comparable to those seen with the natural forms.
And wild salmon is far richer in astaxanthin, compared with farmed fish.
Astaxanthin levels in wild Pacific salmon can be four times higher than in farmed salmon.
Tissue levels in the flesh of farmed Atlantic salmon range from about four to 10mg per kilogram (2.2 pounds), but an FDA study found an average of about 14mg per kg in silver (coho) salmon and about 40mg per kg in sockeye (red) salmon (Turujman et al 1997).
In other words, a six-ounce piece of farmed Atlantic salmon averages 0.75 to 1.65mg of astaxanthin, while the same amount of wild sockeye salmon provides 6.75mg of astaxanthin, or four to nine times as much... all of it in the form found in nature.
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