Fiber first: psyllium, flax and the grams most of us miss.

Fiber is the least glamorous item in a longevity pantry and probably the one most people should start with. US dietary guidelines list it as a nutrient of public health concern because so few people eat enough.

How much to aim for

The adequate intake is 14 g of fiber per 1,000 calories, which works out at roughly 25 g a day for women and 38 g for men under 50, and a little less after that. Typical intakes in the US are around half of that. Beans, lentils, whole grains, vegetables, fruit, nuts and seeds are where most of it should come from. A supplement fills the gap; it does not replace the plants.

Psyllium

Psyllium husk is soluble fiber that forms a gel in water. It is the main ingredient in many bulk-forming fiber products and one of the best-studied. In the US it is one of the few foods with an FDA-authorized health claim: soluble fiber from psyllium husk, as part of a diet low in saturated fat and cholesterol, may reduce the risk of heart disease. The claim is based on about 7 g of psyllium soluble fiber a day.

Two rules for psyllium: take every dose with a full glass of water, and take it at least two hours apart from medicines, because it can slow their absorption.

Flax

Flaxseed brings fiber, the plant omega-3 ALA and lignans. Eat it ground: whole seeds often pass through undigested. One or two tablespoons a day stirred into oats, yogurt or a smoothie is a common amount. Keep ground flax cold and closed, because its oil turns rancid with air and warmth.

Going up without the discomfort

• Add fiber gradually, a few grams a week, so the gut has time to adjust.
• Drink more water as you go.
• Some gas and bloating at first is normal and usually settles within a couple of weeks.

If you have a bowel condition, difficulty swallowing, or take medicines that must be absorbed at precise times, ask your doctor which kind of fiber suits you.

Sources

• US Departments of Agriculture and Health and Human Services, Dietary Guidelines for Americans.
• US Code of Federal Regulations, 21 CFR 101.81: soluble fiber from certain foods and risk of coronary heart disease.

This guide is general information, not medical advice. Talk to your doctor or pharmacist before starting a supplement if you are pregnant or nursing, take medication, or have a medical condition.