Just because your food is full of vitamins and minerals doesn't necessarily mean you're getting the nutrition you need. Some nutrients have poor bioavailability, meaning they can be hard for your body to absorb. The good news is that you can easily increase nutrient absorption with the right food pairings and preparation methods.
Bring on the Fat
Vitamins A, D, E and K are fat-soluble, so for optimal absorption you must consume them with some dietary fat. To get your fill of these nutrients, try adding avocado to your sandwich, nuts to your salad or a teaspoon of olive oil to your soup. Don't go overboard, however, as fat contains more than double the calories of protein or carbohydrates and can easily lead to weight gain. Saturated fats from meat and dairy are also linked to cardiovascular disease, so stick with plant fats for your heart's sake. As a warning, fat-soluble vitamins may accumulate to toxic levels if you consume too much of them; this is most likely to happen if you take supplements.
Add Some Acid
You need iron for healthy blood cells, but much of the iron in foods is the nonheme variety, which is difficult for your body to absorb. Adding some acid to your food, however, will increase the bioavailability of nonheme iron. Vitamin C -- ascorbic acid -- has an especially strong effect on nonheme iron absorption, so add a squeeze of lemon or lime juice to foods such as spinach and beans. In general, iron from plant foods is harder to absorb than iron from animal foods, so vitamin C should be a regular component of vegetarian meals.
Get Your Sunshine Vitamin
Calcium is important for maintaining strong bones and fighting osteoporosis, a condition in which bones become brittle and prone to fracture. However, you need vitamin D to fully absorb calcium; in fact, insufficient vitamin D intake can lead to calcium deficiency even in a calcium-rich diet, according to Jane Higdon, Ph.D., of the Linus Pauling Institute. Fatty fish -- such as salmon -- and fortified milk contain vitamin D, and your body also produces the nutrient naturally with exposure to sunlight. Higdon recommends five to 10 minutes of sun exposure, without sunscreen, two to three times per week to ensure adequate vitamin D production while creating minimal risk from ultraviolet exposure.
Some nutrients -- particularly water-soluble B vitamins and vitamin C -- break down easily with exposure to heat and water. To help keep these vitamins intact, avoid boiling, baking and other extended cooking methods, and instead steam, microwave or lightly saute your food. Remove vegetables from the stove when they turn tender-crisp; greens should still have a bright-green hue.