If protein shakes are just a part of your diet, maybe replacing a meal here and there or used occasionally as a snack, they shouldn't cause you any digestive issues. Having protein shakes several times a day, though, could bind you up. Certain components in protein beverages, such as too much protein, lactose or even gluten, are just some of the things that can leave you constipated.
When they're part of a healthy balanced diet, protein shakes shouldn't cause constipation. But if you're not getting enough fiber, you're lactose or gluten intolerant, or your shakes are overloading your body with calcium, constipation may be an issue.
Lack of Fiber
If you make a protein shake at home, you have the option of piling in lots of fresh produce to add some fiber. Many manufactured ready-to-drink protein shakes have very little fiber. When you don't have much fiber in your diet, food tends to travel through your gut at a delayed pace. Your bowels wind up squeezing out too much moisture, making your stools dry, hard and difficult to pass. If protein shakes make up a big part of your diet, have some fresh fruit, a veggie-rich salad or nuts occasionally. The extra fiber should provide constipation relief.
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Excessive Protein Intake
It's possible to get too much protein in your diet if you drink a lot of protein shakes. When you consume excessive amounts of protein, your kidneys work hard to filter everything out, making you urinate more. You could become dehydrated as a result. The more dehydrated you become, the more water your body absorbs from your stools. This may ultimately leave you constipated.
WebMD recommends that men get 56 grams of protein daily and women consume 46 grams a day. While you can certainly safely consume more than this amount, you should increase your fluid intake. Drink plenty of water to help prevent constipation caused by the increase in protein.
Inability to Digest Lactose
One of the typical key ingredients in protein shakes is milk or milk solids, like whey. Most people should handle this just fine. But if your body doesn't produce much lactase, the enzyme required to digest lactose, you may feel it in your gut. When the lactose reaches your bowels, your body doesn't know what to do with it, causing it to slow things down in some cases. This condition, called lactose intolerance, is also often associated with nausea, vomiting or lightheadedness shortly after consuming something with lactose.
If this is a problem for you, opt for a protein shake that is dairy-free. Alternatively, make your own protein shakes at home, using soy or hemp protein, as well as coconut, rice, almond or soy milk, in place of dairy.
Poor Gluten Digestion
For some, the bowels just don't tolerate gluten — the protein found in several grains. Gluten can also send your immune system into attack mode, which may indicate celiac disease, which causes problems with digestion. Either way, if you know you're sensitive to wheat, rye or barley grains, be wary of protein shakes. Otherwise, you could have constipation.
Generally, premade shakes, or any protein powder you use in shakes at home, don't contain any of these grains. But the manufacturers don't always guarantee that their products were made in a gluten-free facility, and thus your shake's ingredients could be contaminated with gluten. If the final food is tested for gluten, it'll say "gluten-free" on the label.
Read more: Signs & Symptoms of Gluten Intolerance
Too Much Calcium
Calcium is highly beneficial for keeping your bones strong, but too much slows down your bowels. High calcium levels, called hypercalcemia, decrease muscle contraction rates in your intestinal tract. This could be the cause of your constipation. You should never have more than 2,500 milligrams of calcium in any given day. One 10-ounce premade or cow's-milk-based protein shake can provide as much as 385 milligrams of calcium. Having six or seven of them in a day quickly causes you to reach that maximum safe intake level.
- National Institutes of Health: Office of Dietary Supplements: Calcium
- MedlinePlus: Celiac Disease — Sprue
- Merck Manual: Constipation in Adults
- WebMD: Protein: Are You Getting Enough?
- Mayo Clinic: Lactose Intolerance
- Mayo Clinic: Hypercalcemia
- University of Michigan Health System: Hypercalcemia (Increased Calcium in the Blood)
- National Digestive Diseases Information Clearinghouse: Lactose Intolerance
- MedlinePlus: Constipation -- Self-Care