> Africans around Lake Victoria? ate
> spirulina, also high in antioxidents and beta carotene, with their millet.
> Were they long-lived?

Looks like I was thinking of the Kanembu, at Lake Chad.
http://www.millenium2.org/sbgaart/sbgahist.htm

Ancient Spirulina eaters
Freshwater algae also formed an important part of many culinary
traditions,
such as in parts of Africa and Central America. The Kanembu natives of
the
Lake Chad region in Africa have traditionally harvested and eaten
blue-green
algae, using a processing method similar to that used by the Aztec
civilization to remove Spirulina from Lake Texcoco.

The algae is gathered from the lake in porous cloth bags and allowed
to
drain. It is then formed into large flat cakes on the sand and dried
in the
sun. As the blue-green algae gels, it is smoothed by hand and marked
off
into squares. When most of the water has evaporated or seeped into the
sand,
the squares are pulled up, dried further on mats and cut into brittle
cakes.

The Kanembu then eat the algae, which is called dihe, after it is
cooked in
a sauce of tomatoes, chili peppers and various spices; the algae sauce
is
then poured over millet. Unfortunately, much of the chlorophyll and
other
factors are lost by the hot sun, sand drying and cooking.