Have you ever seen the abbreviation RDA on a food label and wondered what it meant? An RDA is a common measurement used on food labels that stands for Recommended Daily Allowance. It’s a nutritional term that shows the daily amount of a nutrient you’d need to consume to meet the requirements of almost all (97%-98%) healthy individuals in every demographic group.
RDA is placed on food nutrition labels as a quick way to provide information about the nutrient content of foods. The RDA value is based on a 2,000-calorie diet and is used to provide guidelines for specific age and sex groups. Its purpose is to tell you the minimum amount of each nutrient you should consume in a day. The National Academy of Medicine establishes these values, and they vary for each nutrient.
The RDA Isn’t Perfect
Although the RDA will give you a rough idea of how much of each nutrient you need each day to avoid deficiency of a particular nutrient, it’s not without flaws. The RDA came into existence around the time of the Great Depression, a time when people had less expendable income and were more likely to be malnourished. The goal was to give the public guidelines for how much of each nutrient they need to avoid nutritional deficiency.
RDA values are a rough measure of what a sedentary person needs to maintain a baseline level of nutrition and avoid deficiency diseases, but it has limitations. The RDA may not be sufficient if you’re highly active, have health conditions that affect nutritional status, or take certain medications that reduce nutrient absorption.
You May Need More or Less Than the RDA
You may need more or less of the established RDA of some nutrients based on your health and activity level. Even lifestyle factors like smoking can affect nutritional needs. For example, smoking creates oxidative stress. Therefore, the cells of a smoker use more vitamin C, an antioxidant vitamin, to fight free radical damage. Research shows smokers need 35 milligrams more vitamin C per day than non-smokers to compensate for this. There’s also evidence that athletes need more vitamin C since intense exercise increases oxidative stress.
The RDA has limitations. It doesn’t identify the daily nutrient needs of all people, only inactive individuals who are otherwise healthy. The RDA of some nutrients also rises in women when they’re pregnant or breastfeeding. Meeting the RDA for a nutrient or nutrients isn’t necessarily enough to optimize health. It specifies the amount you need to avoid deficiency. That’s why some dietitians are critical of the RDA and point out its limitations. They believe it only provides guidelines for maintaining health, not optimizing it.
Reading a Nutritional Label
Assuming you’re healthy, the RDA gives you the amount of each nutrient you need each day to avoid a deficiency. For example, the deficiency disease that comes from too little vitamin C is called scurvy. The RDA for vitamin C is the amount that ensures you won’t develop scurvy. To make it easy to compare one food product to another, labels also contain the %DV, or percent daily value, for each nutrient in a food product.
The %DV is the percentage of each nutrient that a serving of a food product supplies. For example, if a serving of a certain food provides 30% of the daily RDA for magnesium, the percent daily value for magnesium is 30%. Therefore, if you see that a product has a %DV for magnesium of 5% and another supplies 30%, the second product will make it easier to meet your body’s magnesium requirements since it supplies a higher percentage of your body’s daily magnesium needs with each serving.
The RDA Doesn’t Give You the Information You Need to Optimize Your Health
The RDA and %DV are useful references but be aware of their limitations. Avoiding nutritional deficiency and optimizing your health are two different things. Some dietitians believe the best approach is to eat a variety of whole, nutrient-dense foods and get the appropriate number of calories for your age and activity level.
By eating a variety of foods and avoiding empty calories, you can meet your body’s nutritional requirements in most cases. The exception would be if you have health problems or take medications that increase your requirements for some nutrients. For example, some diuretics used to treat high blood pressure or heart conditions can alter your body’s potassium. But if you’re healthy, eat a nutrient-dense diet and exclude most junk food, the nutrients often take care of themselves.
One exception would be vitamin D since food often doesn’t supply enough vitamin D for good health. You need sunlight exposure or a supplement. Another nutrient of concern for vegans is vitamin B12 since it’s naturally only in animal-based foods like meat or dairy. However, some foods, like plant-based milk and cereal are fortified with vitamin B12, meaning they contain added vitamin B12.
The RDA can also change for certain nutrients during pregnancy. For example, the RDA for folate, a B-vitamin, increases by 50% during pregnancy. Another example is smokers need 35% more vitamin C because of the oxidative damage smoking creates. Vitamin C is an antioxidant vitamin.
The Bottom Line
Knowing the RDA and %DV that a food supplies is helpful for nutritional comparisons when you’re buying packaged foods but you should focus on eating a whole, nutrient-dense diet that contains a variety of foods. If you have medical conditions, take medications, or are pregnant, it’s best to consult with a doctor or dietitian about your nutritional needs.
References:
“Vitamin C – Health Professional Fact Sheet.” ods.od.nih.gov/factsheets/Vitaminc-Healthprofessional/.
Hornig DH, Glatthaar BE. Vitamin C and smoking: increased requirement of smokers. Int J Vitam Nutr Res Suppl. 1985;27:139-55. PMID: 3926689.
Carr AC, Frei B. Toward a new recommended dietary allowance for vitamin C based on antioxidant and health effects in humans. Am J Clin Nutr. 1999 Jun;69(6):1086-107. doi: 10.1093/ajcn/69.6.1086. PMID: 10357726.
“The Complete Guide to Recommended Daily Intakes and Daily ….” 28 Jul. 2021, .myfooddata.com/articles/recommended-daily-intakes.php.
“Nutrient Recommendations: Dietary Reference Intakes (DRI).” ods.od.nih.gov/HealthInformation/Dietary_Reference_Intakes.aspx.
“Daily Value on the New Nutrition and Supplement Facts Labels.” 25 Feb. 2022, https://www.fda.gov/food/new-nutrition-facts-label/daily-value-new-nutrition-and-supplement-facts-labels.
“Recommended Intake Individuals – USDA.” https://www.nal.usda.gov/sites/default/files/fnic_uploads/recommended_intakes_individuals.pdf.
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