If someone eats a small amount of sunflower seed shells, nothing is likely to happen as a result. Someone who consumes a large amount of sunflower seed shells may, however, suffer from constipation or an upset stomach.
Sunflower seeds are high in soluble fiber, which can cause bloating and abdominal pain. Someone who consumes a large amount of sunflower seed shells on a regular basis may need to be concerned about weight gain and excessive salt intake. Sunflower seeds are a high-calorie food, and 1/2 cup of salted sunflower seeds contains about 1 gram of salt. Eating sunflower seed shells can also be harmful to tooth enamel and may result in gum sores.