You improved your diet, cut sugar consumption and added high-fiber foods, but now you feel gassy, bloated, and a bit sick sometimes. What gives?

It turns out, some of your healthy food choices may be making you sick!

Why? We expose some stomach-irritating culprits in this article. Read on.

Reasons Healthy Foods Can Cause Digestive Distress

Some of the foods that improve our diets can also cause digestive issues. There are a few reasons why. The first is improper storage.

If you’ve increased protein and fiber intake to help maintain lean muscle mass and healthy cholesterol levels, you’re probably eating more nuts and seeds. This is fabulous because an ounce of seeds can have up to 10 grams of fiber. But, if you notice digestive upset when you start adding these heart-healthy toppings to oatmeal, dishes, and salads, you’re adding too much, too fast. Naturopathic Doctor Martin Milner says we need 20 grams of fiber a day and should aim for up to 40 grams, yet we need to increase slowly. (Learn more about fiber’s cardiovascular protection here.)

But if you’ve been eating more seeds and nuts a couple of weeks and suddenly, they just don’t sit right, the cause is probably improper storage. That’s because nuts and seeds need to be refrigerated or they go rancid fairly quickly. The saturated fats in nuts and seeds are delicate – light and heat can cause them to spoil in a couple of weeks. (Roasted nuts go bad twice as fast as raw nuts.) However, they can last six months to a year in airtight, moisture-free containers in the fridge or freezer. Light-blocking containers help them last longest. If your nuts and seeds taste sour or bitter, throw them out!

It’s also worth noting that some seeds and nuts can irritate your stomach even when new and stored properly. Flax seeds can cause stomach aches, cramps, nausea, and constipation (or diarrhea), especially when you add too much fiber too quickly. In addition to increasing fiber intake gradually, drink more water when you eat them. Or try ground flax seeds, which are easier to digest. Still, flax isn’t for everyone. If you continue to have symptoms, try other types of seeds like chia or hemp.

Raw nuts, especially almonds, can be another gut-irritating culprit. An almond allergy can cause dizziness, stomach cramping, and breathing difficulties. It’s a serious reaction. If this happens to you, seek medical attention immediately. Allergies aside, almonds and other nuts often cause stomach cramps and indigestion because of their phytates and tannins, antioxidant polyphenols that inhibit digestion. These anti-nutrients, or nutrients that block absorption, can wreak havoc in the digestive system.

Dieticians recommend eating smaller amounts to relieve these symptoms. (A serving of sweet almonds is 23.) If that doesn’t help, try soaking, sprouting, boiling or fermenting nuts, seeds, and legumes to remove the anti-nutrients. This almost guarantees easy digestion. What about the crunch? This registered dietician nutritionist recommends soaking and then dehydrating nuts for a safer, crunchy option.

Alternative Sweeteners Can Be Hard on the Gut

You might already be avoiding Splenda (sucralose) and NutraSweet (aspartame) because studies have linked them to an increased risk of cardiovascular disease. Or your doctor may have suggested you avoid them because of other health issues. It turns out that natural sugar alcohol alternatives can also cause problems and are being scrutinized and studied for possible health risks.

Xylitol has become one of the preferred alternatives for many brands and is in gum, mints, health drinks, protein shakes, sugar-free treats, diabetic snacks, barbecue sauces, pancake syrups, and more.

Xylitol is great for oral health, but the body can only handle small amounts of it at first. A range of 10-30 grams of xylitol is considered safe while you build a tolerance, yet even with the lowest amount, you may get gas, bloating, nausea, or diarrhea. We don’t digest xylitol; it passes into the blood stream through the intestines and is absorbed and mostly metabolized by the liver.

If you enjoy foods with xylitol and notice digestive symptoms, cut back and keep a food diary. Increasing xylitol intake slowly can help you build a tolerance. But it’s possible you may not be able to consume xylitol. If you’ve had kidney stones or kidney disease, please talk to your doctor about the safety of consuming xylitol.

(Note: Xylitol is deadly poisonous to dogs and used in reduced-sugar peanut butter and other treats that would otherwise seem okay.)

Erythritol May Be Bad for the Gut and Heart

A worse culprit for many, erythritol is also now in all kinds of food and drinks. Low-calorie ice cream, antioxidant drinks, craft sodas, coffee creamer, sports drinks, baked goods, keto diet food, and even some sweetener packets with “stevia” labels, are sweetened with erythritol.

People tend to prefer the taste of erythritol because it’s more like sugar. However, it’s known to cause digestive distress and recent studies on it cause concern. Like xylitol, erythritol is undigestible. It passes into the bloodstream and is excreted through urine.

Although 30 grams a day is considered a safe amount (that’s about one pint of keto ice cream or three Bai drinks), that may be enough to trigger pain, cramping, headaches, gas, bloating, diarrhea and other digestive issues. It’s suggested that people with irritable bowel syndrome (IBS) avoid erythritol altogether.

Even more concerning, are recent studies showing erythritol may increase your risk of stroke and heart attack. Researchers found that just 30 grams of erythritol was enough to increase blood levels of erythritol a thousandfold for up to three days. Further studies are needed to determine whether erythritol in the blood causes major adverse cardiovascular events (MACE) or is only correlated to them. Nonetheless, if you’ve had previous arterial blockages or have cardiovascular risk factors, please talk to your doctor about erythritol consumption.

In conclusion, if you’ve changed your diet and are now struggling with digestive issues, read the labels closely, check expiration dates, use proper storage, and keep a food diary. What sits well with one person can make you feel horrible. That defeats the point of eating healthier!