How did early food enrichment programs in the 1940s improve public nutrition?

As an immediate solution to widespread undernourishment, food enrichment programs were suggested to restore foods to their pre-processed nutrient levels. Manufacturers voluntarily began adding B vitamins to flour, leading to widespread adoption of enriched flour and bread.

What are the core differences between Estimated Average Requirement (EAR) and Recommended Dietary Allowance (RDA)?

The Estimated Average Requirement (EAR) is the average daily intake needed for about half of individuals. The Recommended Dietary Allowance (RDA) is set two standard deviations above the EAR, designed to meet the needs of 97-98% of the population, functioning as a 'better safe than sorry' target.

What is an Adequate Intake (AI) and when is it used?

An Adequate Intake (AI) is a scientifically less rigorous nutrient target used when there isn't enough research to establish an EAR or RDA. It's typically determined by observing the average intake of a nutrient in apparently healthy populations that aren't experiencing negative effects of inadequate consumption.

What is the Tolerable Upper Intake Level (UL) and how should it be interpreted?

The Tolerable Upper Intake Level (UL) is the amount of a nutrient that can be consumed on an ongoing basis with a very low risk of negative effects from overconsumption. It has a built-in safety margin; slightly exceeding it occasionally is usually fine, but consistent, large excesses may cause problems.

How are nutrient targets like EAR and RDA actually determined for a nutrient like calcium?

For calcium, targets are determined through balance studies that monitor calcium intake versus excretion (urine and feces). Researchers look for the point where calcium balance is neutral (EAR), then calculate two standard deviations above and below for the RDA and LTI, with minor adjustments like accounting for sweat loss.

Why is micronutrient tracking often more imprecise than macronutrient or calorie tracking?

Micronutrient content in whole foods can vary considerably due to factors like season, geography, farming practices, and plant growth cycles. Unlike macronutrients, these variations don't always average out, leading to potentially large and persistent over/underestimations in tracking.

How do vitamin levels in plants vary, and why?

Plants produce vitamins for their own functional purposes (e.g., photosynthesis, hormone production). Their needs for these vitamins vary depending on their growth cycle, season, and environmental stressors, leading to differences in vitamin content over time or by region.

How does bioaccumulation affect nutrient levels in animal products?

Bioaccumulation means certain vitamins and minerals concentrate up the food chain. For example, omega-3 levels are much higher in wild salmon than farmed salmon because wild salmon consume smaller fish that have themselves accumulated omega-3s from plankton. Similarly, mercury bioaccumulates to dangerous levels in predatory fish.

Why are most micronutrients not listed on standard food labels?

Government regulations typically only require food manufacturers to report a small list of high-priority nutrients (energy, macronutrients, sugar, saturated fat, fiber, salt/sodium, and a few specific vitamins/minerals in the US). Listing every essential nutrient would make labels excessively large and detract from key public health messages, and voluntary reporting is rare.

Should individuals in developed countries be highly concerned about their micronutrient intake?

For most people in developed countries with access to diverse food choices and sufficient caloric intake, severe micronutrient deficiencies are rare. While 'insufficient' intake (below optimal but not deficient) can occur, its consequences are usually not serious or immediately obvious. Concerns are mostly warranted for specific medical conditions or highly restrictive diets.

What is the scale of malnutrition globally in 2023?

Sadly, severe malnutrition remains a major global health concern. In 2023, approximately 9 to 10 million people per year die from malnutrition, a significant portion due to micronutrient deficiencies. This is a solvable problem, with an estimated global cost of $40 billion annually to eradicate severe malnutrition.

How did Vitamin D likely contribute to the success of the Vikings?

The Vikings were notably taller and more physically imposing than other Europeans of their time, largely due to sufficient Vitamin D intake from a diet rich in fish, especially cod liver and cod liver oil. This prevented growth stunting common due to rickets and osteomalacia elsewhere in Europe, giving them a physical advantage in raids and contributing to historical shifts like the development of nation-states.

Understanding Micronutrient Targets: What Do They Mean, and Where Do They Come From? (Episode 120)

Stronger By Science

Sports5 min read172 min video

Sep 13, 2023|2,724 views|85|10

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Key Moments

TL;DR

Micronutrient targets (RDAs) are imprecise public health tools. Tracking them is difficult due to food variability and labeling limitations. Focus on ranges, not just RDAs.

Key Insights

Micronutrient targets like RDAs are derived from complex data and include margins of safety, meaning they are often higher than what most individuals need.

The development of Dietary Reference Intakes (DRIs) involves analyzing multiple data points and making informed judgments, leading to inherent imprecision.

Tracking micronutrient intake is challenging due to significant variability in nutrient content within foods (e.g., seasonality, soil conditions) and limitations in food labeling.

While RDAs are useful public health tools to ensure general population adequacy, they should be viewed as ranges (from LTI to RDA) rather than strict targets for individual consumption.

Modern industrialized countries generally have a sufficient food supply for most individuals to meet micronutrient needs without excessive concern, especially if consuming diverse foods.

Specific populations, such as those with darker skin in higher latitudes or individuals with certain health conditions or restrictive diets, may need to pay closer attention to specific micronutrients like Vitamin D.

HISTORICAL ORIGINS OF DIETARY GUIDELINES

The establishment of Recommended Dietary Allowances (RDAs) in 1941 was primarily a response to widespread malnutrition identified during World War II, wherein a significant portion of potential military recruits were found to have diet-related disabilities. This led to the National Nutrition Conference for Defense, which culminated in the first set of RDAs, initially covering six vitamins and two minerals. Early public health messaging focused on food groups, employing stark imagery to encourage adequate nutrient intake, particularly targeting women responsible for household nutrition. The 'Basic Seven' food groups were introduced as a guide, notably including butter as its own category and potatoes with other vegetables, reflecting the economic and nutritional challenges of the Great Depression era.

EVOLUTION OF DIETARY REFERENCE INTAKES (DRIS)

Over time, the framework for nutrient recommendations evolved beyond single RDAs. The US introduced the Dietary Reference Intakes (DRIs) framework, encompassing concepts like the Estimated Average Requirement (EAR) for average needs, Recommended Dietary Allowance (RDA) to cover most of the population, and Lower Threshold Intake (LTI) as a minimum threshold. Adequate Intake (AI) is used when insufficient data exists for EAR and RDA calculations, while Tolerable Upper Intake Levels (ULs) define safe limits for consumption. This comprehensive framework acknowledges the spectrum of nutrient needs, though its updates have been inconsistent, with European agencies like EFSA being more proactive in revising guidelines.

DETERMINING NUTRIENT TARGETS: METHODOLOGY AND CHALLENGES

Establishing nutrient targets involves a rigorous process, beginning with selecting an appropriate analytical endpoint, such as nutrient balance, blood biomarkers, or symptomology. Data is then synthesized through systematic reviews and meta-analyses of existing research, rather than original studies. For example, calcium DRI values are based on calcium balance studies, which track intake versus excretion. However, this process is fraught with challenges: data can be murky, studies may yield conflicting results, and researchers must make judgment calls regarding analytical endpoints and the interpretation of evidence, leading to inherent imprecisions in the final recommendations.

THE IMPRECISION OF MICRONUTRIENT TRACKING

Accurately tracking micronutrient intake is significantly more challenging than tracking calories or macronutrients. Food labels often lack comprehensive micronutrient information, and for whole foods, relied-upon database averages can be imprecise due to substantial variability. This variability stems from factors like seasonality (e.g., vitamin C in spinach), geographical differences in farming practices and soil composition, and even the plant's own needs for vitamins. Consequently, attempts to precisely quantify micronutrient intake can be misleading, with estimates potentially differing by 20-30% or more from actual consumption, often due to factors beyond simple labeling errors.

INTERPRETING MICRONUTRIENT NEEDS: RANGES OVER RIGID TARGETS

Understanding micronutrient needs is best approached by considering ranges rather than isolated targets like the RDA. The LTI represents a minimum threshold, and the RDA covers the vast majority of the population. Consuming within the LTI-to-RDA range is generally considered adequate, with needs varying based on individual factors such as body size and physiological requirements. While RDAs are valuable public health tools for ensuring general population adequacy, overemphasizing them can lead to unnecessary anxiety. For most individuals in developed countries with diverse diets, meeting these targets is less critical than maintaining overall nutritional balance.

PUBLIC HEALTH IMPLICATIONS AND EXCEPTIONS

While most individuals in developed nations with access to varied diets are unlikely to face severe micronutrient deficiencies, global malnutrition remains a significant concern, causing millions of deaths annually. Exceptions to general adequacy include individuals with medical conditions or taking medications that alter micronutrient needs, those following highly restrictive diets, and certain populations, particularly darker-skinned individuals in higher latitudes, who may have lower Vitamin D synthesis rates. In such cases, medical consultation and targeted monitoring are advisable, but for the general population, focusing on a balanced diet is typically sufficient.

BIOLOGICAL FACTORS INFLUENCING MICRONUTRIENT CONTENT

The micronutrient content of food is influenced by various biological factors. In plants, vitamin levels can vary based on the plant's life cycle stage and seasonal needs for processes like photosynthesis or pathogen resistance. Mineral content is largely dependent on soil composition, which can be affected by depletion and agricultural practices. In animal products, bioaccumulation plays a key role; nutrients concentrate up the food chain, leading to higher levels in predators than herbivores. This explains differences in omega-3s in wild versus farmed salmon and high vitamin A levels in apex predators like polar bear liver, though these variations are complex and not always intuitive.

BIOLOGICAL FACTORS INFLUENCING MICRONUTRIENT CONTENT

IMPACT OF MICRONUTRIENTS ON POPULATION HEALTH AND HISTORY

Adequate micronutrient intake, particularly Vitamin D, has had indirect but significant historical impacts. The Viking populations, benefiting from diets rich in fish liver oil, were taller and more imposing than their European contemporaries, influencing historical events like raids and settlements. This nutritional advantage may have contributed to linguistic changes in English by reducing gendered nouns and indirectly affected the development of feudalism and state formation in Europe due to the need for coordinated defense against these formidable groups. These historical ripples underscore how even seemingly simple nutritional factors can have cascading societal consequences.

Mentioned in This Episode

●Supplements

●Software & Apps

●Companies

●Organizations

●Books

●Concepts

●People Referenced

Baby Spinach Vitamin C Content Variability (per 60g serving)

Data extracted from this episode

Season	Vitamin C (mg/serving)	Range
Winter average	26	N/A
Summer average	10	N/A
Overall lowest	5.6	5.6 - 39.6 mg
Overall highest	39.6	5.6 - 39.6 mg

Calcium Daily Intake Requirements (mg/day)

Data extracted from this episode

Measure	US Value	EU (PRI/AR) Value
Lower Threshold Intake (LTI)	~550	N/A
Estimated Average Requirement (EAR)	~750	750 (AR)
Recommended Dietary Allowance (RDA)	1000	950 (PRI)

Vitamin A Toxicity Levels (micrograms per day)

Data extracted from this episode

Exposure Type	Dose (micrograms)	Notes
Tolerable Upper Intake Level (UL)	3,000	Daily long-term consumption, high safety margin
Chronic Toxicity (typical observation)	7,000 - 9,000	Typically observed at 10x RDA
Acute Toxic Dose (lethal)	70,000 - 100,000	Way higher than UL

Common Questions

The first RDAs were released in 1941 during World War II after one-third of American men called for military service were found to be suffering from nutrition-related disabilities. Surveys in the mid-1930s also showed widespread undernourishment in families.

Topics

DRI Framework Nutrient Targets Food Fortification Vitamin Deficiency Mineral Absorption Nutrient Tracking Viking History

Mentioned in this video

personMarshawn Lynch

An athlete who plays the faculty advisor in the movie 'Bottoms'. Praised for his comedic acting, with many lines being improvised.

supplementCalcium Carbonate

A common form of calcium found in supplements. It has decent oral bioavailability, though slightly less than chelated forms.

organizationIodine Global Network

A charity that specifically targets iodine deficiency through programs like salt iodization.

mediaBottoms

A teen sex comedy film, likened to 'Mean Girls' and John Hughes movies, about two gay girls starting a fight club to make out with cheerleaders.

mediaJohn Hughes movies

80s films that 'Bottoms' has hints of, according to the guest.

personPatrick J. Pespas

A charismatic central figure in the 'Telemarketers' documentary who collaborates with the documentarian to investigate the scam.

conceptDietary Reference Intake (DRI)

The general term for scientifically derived reference values for various nutrients used in the US and Canada, comprising EAR, RDA, LTI, AI, and UL.

organizationUnited States Department of Agriculture (USDA)

The government agency that provides databases for food nutrient content, which can be used for manual micronutrient tracking.

conceptAdequate Intake (AI)

A recommended average daily nutrient intake level based on observed or experimentally determined approximations of nutrient intake by a group of apparently healthy people that are assumed to be adequate, used when an RDA cannot be determined.

organizationGAIN (Global Alliance for Improved Nutrition)

A highly-rated charity that takes a holistic approach to helping with food fortification and access in developing countries where severe malnutrition is common.

mediaTelemarketers

A three-part docuseries on HBO investigating scammy telemarketing, particularly focused on a New Jersey operation raising money for public sector unions.

conceptEstimated Average Requirement (EAR)

The estimated average daily nutrient intake level that is estimated to meet the requirements of half the healthy individuals in a given life stage and gender group. The European equivalent is Average Requirement (AR).

mediaReply All 'Long Distance' episodes

A classic Reply All podcast series that covered foreign telemarketing scams, mentioned as another quality production.

mediaThe Gerson documentary

A documentary mentioned as an example of a 'bad but fun' documentary, which takes an unexpected turn into unconventional health practices.

The average daily dietary nutrient intake level sufficient to meet the nutrient requirements of nearly all (97–98%) healthy individuals in a given life stage and gender group. The European equivalent is Population Reference Intake (PRI).

conceptLower Threshold Intake (LTI)

A nutrient intake level two standard deviations below the EAR, representing the bare minimum to consume, below which there's a good chance of insufficient intake.

conceptTolerable Upper Intake Level (UL)

The highest daily nutrient intake level likely to pose no risk of adverse health effects to almost all individuals in the general population; not all nutrients have a UL.

toolHBO

bookMean Girls