Why does eating right sometimes feel so wrong? You could actually get an upset stomach, headaches, and more after eating some healthy foods—these are some of the worst offenders.

A few years ago, I was having a lot of sinus issues, so I went to see an allergist who tested me for both environmental allergies and food allergies. I was convinced the test would tell me I was allergic to dairy and gluten—the big baddies. Instead, it showed I had an intolerance to foods such as salmon, blueberries, bananas, and avocados.

I was allergic to superfoods? Who's allergic to superfoods? I had to eliminate those things from my diet, and then incorporate them again slowly over time. Luckily, most of the sensitivities went away, though I did learn that, just because a food is deemed "healthy," it isn't necessarily healthy for you, especially if you have a sensitive stomach. So I spoke to a couple of nutrition experts to find out what good-for-you foods might make you feel not-so-good.

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Upset stomach after eating healthy foods grocery basket
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1 Cruciferous Veggies

Before you dip into that crudite platter or dig into a broccoli slaw, you should consider whether those raw veggies will give you an upset stomach after eating. "Cruciferous vegetables like cabbage, broccoli, and cauliflower are rich in anti-cancer compounds like indoles and suporafane," explains LA-based nutritionist LeeAnn Weintraub, MPH, RD. "But they also contain a high amount of insoluble fiber which, especially when consumed raw, can cause digestive upset including gas, bloating, and cramps." That doesn't mean you have to skip them entirely, but you might be better off roasting, sautéing, or steaming your veggies in olive oil and cutting down on how much you eat in a sitting.

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2 Milk and Dairy Products

While dairy foods may be full of protein and calcium, the lactose could very well be creating digestive issues for you. In fact, according to the National Library of Medicine (NIH), about 65 percent of the population has a decreased ability to process lactose, an intolerance most common in people of East Asian, West African, Arab, Jewish, and Mediterranean descent. "When an individual eats a food that he/she is sensitive to, they can experience gastric distress, develop headaches, and notice a lack of energy," explains nutritionist Kristin Kirkpatrick, MD, RDN. Those with lactose intolerance tend to get gas, bloating, and abdominal pain after consuming dairy.

3 Citrus Fruits

Despite the fact that they're loaded with immune-boosting Vitamin C, lemons, limes, oranges, and grapefruits can all mess with your digestion. "If you have certain conditions like heartburn or gastritis, the high acidity levels in these fruits can worsen your symptoms," says Weintraub.

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4 Whole Grains

Of course fiber is a good thing to have in your diet. That said, according to Kirkpatrick, too much fiber can be problematic, causing bloating, pain, and constipation, as well as gas and diarrhea. The recommended amount of daily fiber is about 25 grams for women and 38 grams for men, so don't go overboard on the oats and grains, and try to spread out your intake throughout the day so you don't get an upset stomach after eating. Drinking lots of water can also help to minimize any ill effects.

5 Spicy Peppers

You may have heard that spicy foods are the secret to longevity, but too much of a good thing can have painful results. "Spicy peppers like jalapeños are loaded with nutrients and contain a compound called capsaicin, which boosts your metabolism," says Weintraub. "However, some people with sensitive digestive tracts might have difficulty with worsening symptoms after eating spicy foods."

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6 Avocado

This superfruit is a superfood, but if you've ever noticed stomach distress after digging into your avocado toast, you could have a sensitivity. Avocados are a high-histamine food, so if you tend to have food intolerances, this could be one for you. It was for me, and still is to this day, so I can only eat my beloved guac in small doses. Kirkpatrick also points out that if you have gall bladder issues, the high-fat content of an avocado could be triggering as well.

7 Sugar-Free Foods

These days, we're regularly reminded that sugar is the devil, which leads many to flock to sugar substitutes instead. "Sugar alcohols like sorbitol and xylitol are used as weight-loss and diabetes-friendly sweeteners in everything from sugar-free candy to jams to beverages," says Weintraub. "While these products are seen as a more natural sugar alternative, too much can cause gastrointestinal distress including, gas, cramping, and diarrhea." Some are more sensitive than others, but if you notice an upset stomach after eating a sugar-free indulgence, it's probably better just to treat yourself to the real deal.

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