What is the Dietary Reference Intake (DRI)?
The Dietary Reference Intake (DRI) is a system of nutritional recommendations developed by the National Academies of Sciences, Engineering, and Medicine. It is not a single number but a set of four distinct values for planning and assessing nutrient intake:
- Estimated Average Requirement (EAR): The daily nutrient intake level estimated to meet the needs of half the healthy individuals in a particular life stage and gender group.
- Recommended Dietary Allowance (RDA): The average daily dietary nutrient intake level sufficient to meet the nutrient requirements of nearly all (97 to 98 percent) healthy individuals in a particular life stage and gender group.
- Adequate Intake (AI): A recommended average daily nutrient intake level based on observed or experimentally determined approximations of nutrient intake by a group of healthy people. It is used when an RDA cannot be determined.
- Tolerable Upper Intake Level (UL): The highest average daily nutrient intake level likely to pose no risk of adverse health effects to almost all individuals in the general population.
DRI for calcium by life stage
Calcium requirements change significantly across a person's lifespan, with peak needs during adolescence and increasing requirements for older women. Here is a summary of the Recommended Dietary Allowance (RDA) and Adequate Intake (AI) for calcium based on data from health authorities:
| Life Stage | Age | RDA / AI (mg/day) | Rationale |
|---|---|---|---|
| Infants | 0–6 months | Based on mean intake from breastfed infants. | Based on mean intake from breastfed infants. |
| Infants | 7–12 months | Reflects intake from breast milk and solid foods. | Reflects intake from breast milk and solid foods. |
| Children | 1–3 years | To support rapid bone growth and accumulation. | To support rapid bone growth and accumulation. |
| Children | 4–8 years | Continues to support bone development and growth. | Continues to support bone development and growth. |
| Adolescents | 9–18 years | Crucial for building peak bone mass. | Crucial for building peak bone mass. |
| Adults | 19–50 years | Supports bone maintenance and density. | Supports bone maintenance and density. |
| Older Adults | Men 51–70 years | Maintains bone health during aging. | Maintains bone health during aging. |
| Older Adults | Women 51–70 years | Addresses accelerated bone loss after menopause. | Addresses accelerated bone loss after menopause. |
| Older Adults | 71+ years | Accounts for further declines in calcium absorption with age. | Accounts for further declines in calcium absorption with age. |
| Pregnancy/Lactation | 14–18 years | Meets high demand for both mother and growing fetus/infant. | Meets high demand for both mother and growing fetus/infant. |
| Pregnancy/Lactation | 19–50 years | Metabolic adaptations increase absorption during this period. | Metabolic adaptations increase absorption during this period. |
Factors influencing calcium absorption
Several factors can affect how well your body absorbs and utilizes calcium. A primary factor is vitamin D, which is essential for calcium absorption. Without sufficient vitamin D, the body cannot absorb enough calcium, regardless of intake. Conversely, high-dose vitamin D supplementation without adequate calcium intake is ineffective for bone health.
Other factors impacting absorption include:
- Age: Absorption rates are highest in infants and young children (around 60%) to support rapid bone growth, but decrease to about 25% in adulthood and continue to decline with age.
- Dietary elements: Compounds like oxalic acid and phytic acid, found in certain vegetables and grains, can bind with calcium and slightly reduce absorption, though this effect is generally minimal in a varied diet.
- Caffeine and phosphorus: High intakes of caffeine and phosphorus can also slightly reduce net absorption.
Meeting your DRI through diet and supplements
The best way to meet your calcium DRI is through diet. Dairy products such as milk, yogurt, and cheese are excellent sources. For those who are lactose intolerant or prefer non-dairy options, fortified foods like some orange juices, plant-based milks, and cereals are available. Some green leafy vegetables like kale and broccoli, as well as canned sardines and salmon with bones, also provide calcium.
Food sources of calcium:
- Milk, cheese, yogurt
- Fortified juices and plant-based milk alternatives
- Green leafy vegetables (e.g., kale, broccoli)
- Sardines and canned salmon with bones
- Calcium-set tofu
For individuals who cannot meet their needs through diet alone, supplements are an option. Common supplement forms include calcium carbonate and calcium citrate. Calcium carbonate is best absorbed when taken with food, while calcium citrate can be taken at any time. It is advisable to choose supplements with a USP (United States Pharmacopeia) symbol, which indicates government-level standards for purity and quality.
Potential health risks of too much calcium
While important, it is also possible to consume too much calcium, particularly through high-dose supplements. Exceeding the tolerable upper intake level (UL) can increase the risk of adverse health effects.
Tolerable Upper Intake Levels (UL) for calcium:
- Infants (0-6 months): High intake should be avoided
- Infants (7-12 months): High intake should be avoided
- Children (1-8 years): High intake should be avoided
- Children (9-18 years): High intake should be avoided
- Adults (19-50 years): High intake should be avoided
- Adults (51+ years): High intake should be avoided
- Pregnant and lactating teens: High intake should be avoided
- Pregnant and lactating women (19-50): High intake should be avoided
Excessive intake may increase the risk of kidney stones, and some research has suggested a possible link between high supplemental calcium intake and increased risk of cardiovascular disease, especially in older women. This underscores the importance of discussing supplementation with a healthcare provider.
Conclusion
The Dietary Reference Intake for calcium (DRI) is a valuable tool for guiding optimal nutrient intake throughout life. By recognizing how requirements change with age and life stage, individuals can make informed dietary choices to support bone health and other critical physiological functions. Prioritizing calcium-rich foods and using supplements responsibly, if needed, under the guidance of a healthcare professional is key to achieving and maintaining proper calcium levels without risking the adverse effects of excessive intake. A balanced approach to nutrition is always the most beneficial strategy for long-term health.
Learn more about dietary guidelines from the Office of Dietary Supplements at the National Institutes of Health.(https://ods.od.nih.gov/factsheets/Calcium-HealthProfessional/)
