Simple sugars and refined carbs are the biggest contributor to high triglyceride levels. Avoid added sugars and concentrated fructose in things such as sodas, granola, and canned fruit in syrup. In addition cutting back on alcohol and avoiding trans fats as well as getting in some physical activity have been shown promising. Healthy fats such as omega-3s from hemp seeds, flax seeds, salmon, etc. and of course eating plenty of nutrient-rich veggies!