Diet: For every 1% increase in omega-3 intake, HDL levels rise by 2.5 mg/dL

HDL levels lower than 40 mg/dL are considered a risk factor for heart disease, while levels of 60 mg/dL or higher are thought to be optimal.

Omega-3 fats, for instance, have been linked to lower risks of age-related vision loss and dementia among older adults.

Fish Oil Comes from “The Most Important Fish in the Sea”: Menhaden

Nearly every fish a fish eater likes to eat eats menhaden (shown here). Bluefin tuna, striped bass, redfish and bluefish are just a few of the diners at the menhaden buffet. All of these fish are high in omega-3 fatty acids but are unable themselves to synthesize them. The omega-3s they have come from menhaden.

References:

Diet changes improve older adults' cholesterol too | Reuters.
http://www.reuters.com/article/idUSTRE61I49N20100219

Fish Oil Comes from “The Most Important Fish in the Sea”: Menhaden

Monounsaturated fats found in vegetable oils, nuts and avocados increase "good" HDL cholesterol levels by 12% http://goo.gl/GBQa5
How We Eat: Analyzing Half a Million Meals - 5 INFOGRAPHICS

Image source: Menhaden B. tyrannus from the Chesapeake Bay. Wikipedia, Brian.gratwicke, Creative Commons Attribution 2.5 License.