Yeast-derived fiber has been demonstrated, as described herein, to effectively improve the serum lipid profile in humans, when provided as a dietary supplement, without some of the disadvantages known to accompany dietary supplementation with oat fiber or psyllium fiber. Described herein are dietary supplements comprising yeast fiber, e.g., .beta.-glucan or glucomannan, and further comprising folic acid or a salt thereof, vitamin B.sub.6, vitamin B.sub.12, and vitamin E. The dietary supplements of the invention can further comprise fats, carbohydrates and proteins, for example, and other ingredients added to formulate a food product. Such food products can be in the form, for example, of solid or semi-solid foods, such as food bars, pudding, or spreads. By including folate and vitamin B.sub.6, the dietary supplement provides a second benefit of suppressing the level of homocysteine in the blood. A third benefit is provided by the anti-oxidant properties of vitamin E, particularly the effect of preserving low density lipoproteins from oxidation. Further embodiments of the invention are methods for improving the serum lipid profile in a human, methods for lowering risk of heart disease, and methods for improving cardiovascular health in a human, comprising administering to the human a dietary supplement of the invention.