Fiber supplements and fibermaxxing: how much fiber you need, and how to get it

Most adults need about 25 to 38 grams of fiber a day, and most get only about 15. That gap is what the "fibermaxxing" trend is trying to close, and dietitians mostly agree with the goal. The catch is speed: jumping to a huge amount too fast causes gas, bloating and cramps, and doubling the target has no proven extra benefit. Food comes first, and a fiber supplement can help fill the gap. Here is how much you need, how to increase it, and how to choose a supplement.

General information, not medical advice. If you have IBS, Crohn's disease, ulcerative colitis, have had bowel surgery, or take medicines, talk to a doctor or dietitian before increasing fiber.

How much fiber do you need?

UCLA Health, citing the US Department of Health and Human Services, gives 25 grams a day for women and 38 for men. The Harvard Nutrition Source says adults need at least 25 to 35 grams. A CU Anschutz article lists targets that change with age:

Most people fall well short. UCLA Health reports that more than 90% of women and 97% of men miss the target, and Harvard puts the average intake at about 15 grams a day.

What is fibermaxxing?

Fibermaxxing is a social media trend that encourages people to eat much more fiber, with some influencers promoting 50 to 70 grams a day or more. UCLA dietitian Yasi Ansari points out that the name is a misnomer: there is no upper limit for dietary fiber, so the useful goal is reaching the recommended amount steadily, not maxing out. CU Anschutz dietitian Bonnie Jortberg says there is no evidence that doubling or tripling the target adds benefit, and very high amounts can cause bloating, gas and diarrhea.

So the trend is right about the problem and wrong about the extreme. Getting from 15 grams to 25 or 30 is the win.

Why fiber matters

The sources describe these benefits:

• Regularity: fiber softens and bulks stool and helps food move through the gut.
• Cholesterol: soluble fiber modestly lowers LDL cholesterol, according to a meta-analysis cited by Harvard.
• Blood sugar: soluble fiber helps regulate it, and diets low in fiber are linked to higher type 2 diabetes risk.
• Fullness: fiber increases satiety, which helps with weight management at recommended intakes.
• Long-term risk: higher fiber intake is linked with lower risk of heart disease, diverticular disease and colorectal cancer. These are associations from population studies, not guarantees.

Soluble vs insoluble fiber

Soluble fiber dissolves in water to form a gel; it is the type linked to cholesterol and blood sugar. Sources include oats, barley, chia seeds, beans, lentils, apples and blueberries. Insoluble fiber does not dissolve and adds bulk that keeps things moving; sources include whole wheat and bran, brown rice, quinoa, leafy greens, nuts and fruit skins. Most plant foods contain both.

High-fiber foods to start with

• Breakfast: oats with berries and chia or ground flax.
• Beans and lentils: some of the most fiber-dense foods there are; add them to soups, salads and pasta.
• Whole grains in place of white: brown rice, quinoa, whole-wheat bread and pasta.
• Whole fruit instead of juice, and vegetables at every meal.
• Nuts and seeds as snacks or toppings.

UCLA Health notes a label tip: a food that provides 20% or more of the Daily Value for fiber counts as high in fiber.

Should you take a fiber supplement?

Food comes first, because high-fiber foods also bring vitamins, minerals and other nutrients. But intake is so low that Jortberg, who generally dislikes supplements, makes an exception for fiber. Harvard also notes that supplements such as psyllium can help, without replacing high-fiber foods.

How to increase fiber without the bloating

1. Go slowly. Add a few grams a week rather than doubling overnight. UCLA Health and Harvard both warn that a sudden jump causes gas, bloating and cramping.
2. Drink more water as you add fiber, especially with supplements; too little water can make constipation worse.
3. Expect an adjustment period. Jortberg notes that discomfort can last a week or two as your body adjusts.
4. Spread it across the day rather than one huge fiber meal.
5. Keep eating protein. Fiber should add to meals, not crowd out everything else.

Who should be careful

People with IBS, Crohn's disease or ulcerative colitis, and anyone who has had bowel surgery, should get advice before increasing fiber, according to UCLA Health and CU Anschutz. Fiber supplements can also change how some medicines are absorbed, so ask a pharmacist about spacing them apart.

For more on daily habits that support how you feel, see our guides to magnesium for sleep and lowering cortisol.

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