Rich in healthy fats and a good source of fiber, protein, iron, vitamin E and several of the B vitamins, sunflower seeds can be a healthy addition to your diet. But, like anything in life, moderation is key. Consuming too much, even of healthy foods like sunflower seeds, can lead to unwanted effects, such as weight gain and excess sodium intake. It's best to stick to a standard serving of the seeds, which is about 1 ounce, to avoid potential dangers.
Eating too much of any food can cause unwanted weight gain. Gaining weight is most often the result of eating more calories than your body burns. When your body can't use the calories you consume, it stores them as fat. Your calorie needs depend on several factors including your sex, age and activity level. One 1-ounce serving of toasted sunflower seed kernels provides 175 calories, which is almost 10 percent of a typical daily calorie intake of 2,000 calories. If you eat two, three or even five times that amount, you could be getting as much as 875 calories in one sitting. Eating that many sunflower seeds on top of your regular diet will lead to excess calorie intake and weight gain.
Excess Saturated Fat Intake
Sunflower seeds are a rich source of the healthy mono- and polyunsaturated fats that have been shown to improve heart health, however, they are also a source of saturated fatty acids, an excess of which may lead to increased levels of unhealthy low-density lipoprotein, or LDL cholesterol. The American Heart association recommends that people limit their saturated fat intake to no more than 7 percent of calories, which would be 140 calories on a 2,000-calorie diet. One serving of toasted sunflower kernels contains 1.7 grams of saturated fats, which is equal to 15 calories from fat, since fats have 9 calories per gram. If you ate 5 ounces of sunflower seeds in one sitting, you'd be getting 75 calories from saturated fat, which is more than half of your daily saturated fat limit. This could cause problems if you eat other foods high in saturated fat in addition to sunflower seeds.
Potential Sodium Trap
Some kinds of sunflower seeds are salted during processing. The USDA's National Nutrient Database reports that 1 ounce of toasted, salted sunflower seed kernels provides 174 milligrams of sodium. The American Heart Association recommends that people eat less than 1,500 milligrams of sodium per day to prevent high blood pressure and cardiovascular disease. One ounce of salted sunflower seeds provides 12 percent of that limit, which makes them an acceptable snack if you don't indulge in salty foods at other meals. However, if you eat a 5-ounce portion, you'll be getting nearly 60 percent of your daily sodium limit in one snack, which means you'll likely go over your sodium limit by the end of the day.
Other Possible Problems
Sunflower seeds are high in several other nutrients, large intakes of which could pose dangers to your health. For example, 5 ounces of sunflower seeds contain 1,621 milligrams of phosphorous, which is 232 percent of the recommended daily intake. Five ounces of sunflower seeds also provide 111 micrograms of selenium, which is 202 percent of the daily recommended intake. Excess intake of either of these nutrients can cause serious problems. Phosphorous toxicity can lead to calcification of non-skeletal tissues and kidney damage, and selenium toxicity can result in symptoms of selenosis, including brittle hair and nails, skin rashes, fatigue and irritability, and even death. A five-ounce portion of sunflower seeds provides almost 30 percent of the tolerable upper intakes set by the Institute of Medicine for both phosphorous and selenium.