What are dietary ceramides, and which foods contain them?

Ceramides are fats (lipids) of the sphingolipid family. Each ceramide is a long-chain base, called a sphingoid base, joined to a fatty acid. In plant foods, most ceramide carries a glucose sugar and is called glucosylceramide; studies have measured it in soybeans, wheat germ and rice. When eaten, sphingolipids are broken down in the digestive tract into ceramides and sphingoid bases. There is no known nutritional requirement for sphingolipids, and ceramides are not nutrients with a Thai Reference Daily Intake (Thai RDI).

In short:

• What they are: lipids of the sphingolipid family, a sphingoid base plus a fatty acid
• In plant foods: mostly glucosylceramide, a ceramide with one glucose attached
• Foods studied: soybeans, wheat germ, rice; among sphingolipids as a whole, dairy products, eggs and soybeans are rich sources
• Skin creams and food: different kinds of ceramide
• When eaten: broken down in the digestive tract
• Daily amount: no known nutritional requirement; no Thai RDI

This article explains what ceramides are, which foods contain them and what happens to them in digestion. For another group of food lipids, the phospholipids, see What is lecithin, and where does it come from?

What are ceramides?

A kind of sphingolipid

The US National Library of Medicine's MeSH vocabulary describes sphingolipids as a class of membrane lipids with a polar head and two nonpolar tails. They are built from one molecule of a long-chain amino alcohol, sphingosine or one of its relatives, and one molecule of a long-chain fatty acid, with a polar head group and sometimes phosphoric acid.

A 1999 review from Emory University in Atlanta explains that what all sphingolipids have in common is this sphingoid base backbone. In a ceramide, the sphingoid base is joined to a fatty acid.

Glucosylceramide: the main form in plants

A glucosylceramide is a ceramide with one glucose attached. Because plants mainly make cerebrosides, most of the ceramide in plant foods comes in this form. A 2006 study at Iowa State University names glucosylceramide and ceramide as the main sphingolipids in soybeans, with far more glucosylceramide than free ceramide.

Plant and animal cerebrosides differ

The US National Library of Medicine's MeSH vocabulary defines cerebrosides as a ceramide joined to one sugar, normally glucose or galactose. It notes that in plants the sugar is normally glucose and the sphingoid base is usually phytosphingosine, while in animals the sugar is usually galactose and the sphingoid base is usually sphingosine or dihydrosphingosine. MeSH also describes sphingosine and its relative sphinganine as the major bases of the sphingolipids in mammals.

Which foods contain ceramides?

Food composition tables do not usually list ceramides, so the figures below come from individual studies. They use different units and bases (fresh food, dry weight, total sphingolipids or glucosylceramide only), so they cannot be compared with each other directly.

Soybeans: the variety and the stage of growth

In the Iowa State study of 15 soybean lines, the lines differed widely in palmitic acid, from 3.7% to 40.7% of their fatty acids, but this was not linked to how much glucosylceramide or ceramide they had. The researchers concluded that other genetic factors explain the differences between lines.

The same group followed three soybean varieties as the seeds grew, from 28 to 68 days after flowering. Averaged across the varieties, glucosylceramide fell from 522.8 to 135.8 nmol per gram of dry weight, and ceramide from 51.4 to 22.2 nmol per gram. Mature soybeans, the kind sold as dried beans, are at the end of this range.

Wheat germ and food by-products

A 2017 study from Martin Luther University Halle-Wittenberg and the Leibniz Institute of Plant Biochemistry in Germany purified glucosylceramides from three by-products of the food industry: wheat germ, apple pomace and used coffee grounds. It identified 45 different glucosylceramides, varying in their sphingoid bases and their fatty acids, which had 15 to 28 carbons. The three amounts in the table come from this study.

Does cooking change the ceramides in food?

Rice: boiled rice and rice porridge

A 2024 study from Obihiro University of Agriculture and Veterinary Medicine and Tohoku University used a model of digestion in a test tube, not people, and measured how much glucosylceramide moved out of cooked rice into the digestive fluid, not how much the body absorbs. More moved out of rice porridge than out of boiled rice. With boiled rice, the amount differed between rice varieties, while with porridge it did not, and the differences were related to the share of amylose in the starch and the amount of water added. The authors concluded that glucosylceramide in rice was not fully released during digestion.

What happens to ceramides when you eat them?

The Emory review explains that sphingolipids in food are broken down throughout the digestive tract into ceramides and sphingoid bases. For fats in general, the NIDDK, part of the US National Institutes of Health, explains that the pancreas makes a digestive juice with enzymes that break down fats, and the liver makes bile, which helps digest fats.

How do ceramides in skin creams differ from ceramides in food?

They are different materials with different uses. The German study notes that ceramides are major components of the outermost layer of the skin, the stratum corneum. It describes the ceramides used on the skin as semi-synthetic ceramides made to match those in human skin, and its own work was about making plant ceramides by removing the glucose from glucosylceramides with an enzyme.

Is there a recommended daily amount?

No. The Emory review states that there is no known nutritional requirement for sphingolipids. Ceramides are not nutrients with a Thai Reference Daily Intake (Thai RDI), so there is no recommended daily amount in Thailand.

How much do people eat?

Using the limited data available, the Emory review estimated that people in the United States ate about 150 to 180 mmol (about 115 to 140 g) of sphingolipids a year, or about 0.3 to 0.4 g a day. This is an estimate from 1999 for one country, covers all sphingolipids rather than ceramides alone, and no comparable estimate was found for Thailand.

Who should talk to a doctor or pharmacist?

People with a wheat or soy allergy

Ceramide ingredients can be made from wheat, soy and other plants. The US Food and Drug Administration lists wheat and soybeans among the nine major food allergens and explains that food allergies happen when the body reacts to certain proteins in food. People with these allergies should ask a doctor or pharmacist before eating products made from them.

Pregnant or breastfeeding women and people who take regular medication

If you are pregnant or breastfeeding, or take medication regularly, check with a doctor or pharmacist before taking supplements.

Dietary supplements are not intended to prevent, treat or cure any disease.