A cardiologist eats 90 grams of fiber a day without trying. Here's her breakfast, lunch, and dinner.

• Most Americans eat half the recommended daily amount of fiber.
• A vegan cardiologist eats 90 grams of fiber a day thanks to her plant-based diet.
• Fiber can lower "bad" cholesterol levels, help you feel full, and reduce the risk of cancer.

Most of us don't eat enough fiber. Not Dr. Danielle Belardo, though.
She routinely eats a whopping 90 grams a day, more than most Americans get in a working week.

"There's no guideline that says anyone should reach 90 grams of fiber a day, it just happens to be what I eat," Belardo, a vegan cardiologist practicing in Los Angeles, told Business Insider.

The general recommendation is for fiber to make up 14 grams of each 1,000 calories we consume. That amounts to at least 25 grams a day or the fiber in two cups of black beans. But only 10% of Americans actually get that much fiber. Most are lucky if they get even half of that.

A high-fiber diet packed with foods such as fruits, vegetables, and whole grains, helps the body remove waste products, like bile acid, and effectively sucks "bad" cholesterol out of the bloodstream. Low-fiber diets are linked with poor heart health, higher rates of diabetes, high blood pressure, and cancers, including colon cancer and breast cancer.

But "fibermaxxing" by suddenly increasing the fiber in your diet if your body isn't used to it can lead to bloating, gas, and stomach cramps. So, it's advised to add fiber to your diet slowly and steadily, making sure you're staying well-hydrated along the way.

Here's how Dr. Belardo beats out just about everybody else when it comes to packing fiber (and protein) into her daily meals.

Breakfast: a smoothie, with berries, protein powder, and frozen spinach

Belardo's typical breakfast smoothie:

• 1 cup of frozen raspberries (8 g of fiber)
• 1 cup of frozen blackberries (8 g)
• 1 cup of spinach (1 g)
• 1 scoop of protein powder (4 g)

Fiber from breakfast: 21 g

Belardo has nearly hit the daily target for women, which is 25 to 28 g, and she has only just started her day!

Lunch: avocados, beans, and whole grains

At lunchtime, Belardo does some variation on a grain bowl.

A fiber-rich lunch:

• 1 whole avocado (10 g)
• 1/2 cup of black beans (7.5 g)
• 1 cup of quinoa (5 g)
• 1 cup of Brussels sprouts (4.5 g)
• 1 Tbsp of chia seeds (5 g)

Fiber from lunch: 32 g

Total fiber consumed so far: 53 g

Dinner: pasta, chickpeas, broccoli, and beans

"Bean pastas are such a great option to get high fiber in," she said. She often recommends these to her patients looking to lose weight and improve their heart health.

Fiber fills you up, and fiber-rich foods tend to replace other, less nutrient-dense foods in a person's diet.

"If you're eating 30 grams of fiber from fruits and vegetables, that is naturally only going to displace something else that may be less health-promoting," she said.

Belardo added: "You can do lentil or chickpea, but one that's got a super high amount of protein and fiber that I love is edamame and mung bean pasta."

A high-fiber dinner:

• 1 1/2 cups of cooked edamame and mung bean pasta (24 g)
• 1/2 cup of cooked chickpeas (6 g)
• 1 cup of broccoli (5 g)
• 1 Tbsp of black beans (1 g)

Fiber from dinner: 36 g

Total daily fiber: 89 g (Her average daily fiber intake, she said, tends to be about 90 grams, give or take).

It's better to get fiber from foods than supplements

Supplements can help level out deficiencies, but Belardo doesn't typically recommend them, because fiber-rich foods have so many benefits that simply can't be replicated by a pill or powder.

"It's not just the fiber itself that's beneficial, it's the food it comes packaged with," Belardo said. "It's also coming with phytonutrients, vitamins, minerals, antioxidants and all these other things."