Based on many things, including nutrition, women are not the same as men. However, it is rarely appreciated how nutrient needs differ between the genders and how these differences translate into the foods consumed.

QUESTION: How do nutrient needs differ between the genders?

ANSWER: Both genders need the same essential nutrients. However, there are some significant gender differences in the quantities of specific nutrients needed to produce the optimal diet for health.

The recommended daily iron intake for an adult woman (before menopause) is about twice that for a man. The recommended iron intake for a man is 8 milligrams per day, while the recommendation for a woman is 18 milligrams.

The form of iron in red meats is absorbed by the intestine much better than the iron found in plant foods. Consequently, from a nutrient perspective, it is much easier for a man to meet his iron needs with a vegetarian diet than it is for a woman. Also, without meat in the diet, the efficiency of iron absorption decreases. As a consequence, the recommended daily iron intake for vegetarians increases by 80 percent to ensure that an adequate amount of iron can be absorbed. This increases a woman’s recommendation from 18 to 33 milligrams of iron daily.

Q: How does pregnancy change nutrient needs?

A: During pregnancy, a woman’s needs for some key nutrients increase greatly. The recommendation for iron rises from 18 to 27 milligrams per day with a mixed diet that includes meat and to 50 milligrams per day with a vegetarian diet. That is four to six times the recommended intake for a man. Consequently, iron supplements commonly are recommended during pregnancy.

Iodine, zinc, folic acid and vitamin B6 recommendations also increase by 40 percent to 50 percent, matching or exceeding the recommendations for men. In addition, most other nutrient needs increase slightly during pregnancy.

Pregnant women need to consume reasonable amounts of good iron and zinc sources such as red meat or consider a dietary supplement on the advice of their physician.

Seafood, including seaweed, can help to meet increased iodine needs. Increased folic acid needs can be met by including plenty of fruits and vegetables and vitamin B6 will likely be met by the overall increase in total food consumption.

Q: How does breast-feeding affect nutrient needs?

A: Due to a lack of menstrual iron loss while breastfeeding, the recommended intake of iron drops to 9 milligrams per day — about the same as a man. However, many women come out of pregnancy with depleted iron reserves. Consequently, maintaining a higher iron intake during breast-feeding may be important for some women.

Vitamin A and C needs increase well above the intake recommended during pregnancy. Iodine needs rise to almost twice the recommendation for men and most of the B vitamin needs remain at or above those during pregnancy.

As men often point out, women are complex. This is certainly true when it comes to nutrient needs. Since, on average, women require fewer calories than men, most women need to meet nutrient needs within a calorie intake lower than that of men. So women need to eat a good variety of wholesome foods from all of the key food groups and stay physically active to keep calorie needs up.

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Joannie Dobbs, Ph.D., C.N.S., and Alan Titchenal, Ph.D., C.N.S., are nutritionists in the Department of Human Nutrition, Food and Animal Sciences, College of Tropical Agriculture and Human Resources, University of Hawaii-Manoa. Dobbs also works with University Health Services.