Natural Beta Carotene by Nature"s Plus 90 Softgel Natural Beta Carotene From Dunaliella salina algae. Nature"s Plus Natural Beta Carotene Softgels contain 25 000 IU of Vitamin A activity and no chemicals or preservatives are used in production. Dunaliella salina is a single-celled algae cultivated in seawater or salt lakes producing 10 000 times more Beta Carotene than carrot cells.