ICMR-NIN Study Links Vitamin Deficiencies to Cognitive Decline and Higher Dementia Risk in Older Adults

As India’s population ages, the conversation around Healthy Ageing is moving beyond blood pressure, diabetes and heart disease to a quieter but equally consequential question: what happens to the brain when nutrition is inadequate for years? A new ICMR-National Institute of Nutrition (ICMR-NIN) study from Telangana adds important evidence to that discussion, finding an association between vitamin deficiencies, dietary patterns and a higher burden of Dementia risk factors.

The community-based study, conducted during 2023–2024, examined 556 adults with a mean age of 63 years, covering both rural and urban populations. Researchers measured blood levels of several vitamins and assessed participants using an India-specific version of the CAIDE dementia-risk score. About 39% of participants fell into the study’s higher predicted dementia-risk category.

The most striking finding was not that one particular vitamin “causes” memory loss. Rather, the study points toward a broader nutritional pattern: people carrying a higher dementia-risk burden were more likely to have deficiencies in several micronutrients and less diverse diets. Vitamin B2 deficiency was particularly common, while vitamin D, B6, folate and B12 deficiencies also emerged as important signals.

That distinction matters. The research is cross-sectional, so it cannot prove that vitamin deficiency causes dementia or that taking supplements will prevent it. But it strengthens the case for treating nutritional health as part of the larger healthy-ageing strategy rather than as an issue separate from brain health.

What did the ICMR-NIN study actually find?

The study recruited adults aged 40 to 80 years through community health outreach camps across four geographical regions of Telangana. Researchers ultimately analysed 556 participants after initially approaching a much larger pool.

The researchers calculated an India-specific CAIDE score using factors including age, sex, education, body mass index, physical activity, systolic blood pressure and total cholesterol. A score of 9 or higher was classified as the high-risk group for the study.

Of the 556 participants, 215, or 38.6%, were in the high-risk group. The remaining 341 participants were classified in the lower-risk group.

The nutritional findings were especially noteworthy:

• Vitamin B2 deficiency: 64% of participants
• Total vitamin B12 deficiency: 47%
• Vitamin D deficiency: 42%
• Vitamin B6 deficiency: 34%
• Active B12 deficiency: 17%
• Folate or vitamin B9 deficiency: 7.7%
• Vitamin B1 deficiency: 2.8%
• Vitamin A deficiency: 1%

Deficiencies in vitamin D, B2, B6 and B9 were more pronounced in the higher-risk group. The researchers also identified weak inverse relationships between CAIDE scores and blood levels of vitamin D, B2, B6, folate, total B12 and active B12.

Why vitamin deficiencies may matter for brain health

The brain is an energy-intensive organ that depends on a steady supply of micronutrients for neurotransmitter production, cellular metabolism, DNA synthesis and maintenance of nerve cells. Vitamins do not operate in isolation; many work as components of biochemical pathways that keep neurons functioning.

Vitamin B12 and folate, for example, are involved in one-carbon metabolism and homocysteine regulation. Persistent abnormalities in these pathways have been studied in relation to neurological health. B vitamins also participate in processes involved in energy production and nervous-system function.

Vitamin B6 contributes to neurotransmitter synthesis and amino-acid metabolism, while vitamin B2 is central to cellular energy metabolism and redox reactions. Vitamin D has receptors in the brain and has been investigated for possible roles in neuroinflammation, neuronal signalling and other pathways relevant to ageing.

However, biological plausibility should not be confused with proof of prevention. A nutrient can be essential for normal brain function without supplementation necessarily preventing dementia in people who already have adequate levels.

The biggest insight may not be about vitamins at all

The most useful lesson from this study may be its emphasis on dietary diversity.

Modern nutrition coverage often turns complex problems into a search for a single “brain vitamin”. The evidence emerging from the Telangana study suggests a different approach. Participants with higher dementia-risk scores had less diverse diets and differences in the types of foods they consumed.

The high-risk group reported lower consumption of foods such as dairy products, nuts and seeds and certain vegetables. Their diets also contained relatively more bakery products, processed foods, meat and poultry, while some nutrient-rich food groups were consumed less often.

This creates an important distinction between nutrient adequacy and diet quality. A person may obtain enough calories while still falling short on several vitamins and minerals.

In other words, ageing does not make the body interested only in eating less. It makes the quality of what is eaten increasingly important.

Rural-urban differences deserve closer attention

One of the study’s most important public-health signals was the difference between rural and urban participants.

The predicted dementia-risk burden was substantially higher among rural participants: approximately 60% of the rural group versus 27% of the urban group. Several vitamin deficiencies, including vitamin D, B2, B6, folate and B12, were also more prevalent among rural participants.

This should not be interpreted as evidence that rural living itself causes cognitive decline. Rural populations can differ from urban populations in education, healthcare access, income, food availability, occupation, physical activity and patterns of chronic disease. These factors can interact in complicated ways.

Nevertheless, the finding points to an overlooked policy question: are nutrition and healthy-ageing programmes reaching older adults with the same intensity across rural and urban India?

Screening for nutritional deficiencies may be particularly relevant when older adults have restricted diets, chronic illnesses, poor appetite, difficulties chewing or swallowing, limited mobility or reduced access to healthcare.

Why vitamin B12 deserves special attention

Vitamin B12 is particularly relevant to older adults because deficiency can have neurological manifestations. It is also possible for B12 status to become complicated by dietary patterns and problems with absorption.

The study found total B12 deficiency in 47% of participants, although the researchers used laboratory thresholds specific to their methodology. Active B12 deficiency was lower, at 17%.

This difference is a useful reminder that “B12 level” is not always a simple yes-or-no question. Total circulating B12 and biologically available B12 do not provide exactly the same information.

For older adults experiencing unexplained cognitive changes, numbness, weakness, balance problems or other neurological symptoms, nutritional assessment may therefore form part of a broader medical evaluation. It should not, however, replace assessment for other causes of cognitive impairment.

Vitamin D: a signal, not a dementia cure

Vitamin D deficiency affected 42% of the study population. Blood vitamin D levels also showed an inverse relationship with CAIDE scores, and vitamin D deficiency remained independently associated with a higher dementia-risk factor burden after adjustment in the researchers’ analysis.

But this finding needs careful interpretation.

A vitamin D deficiency can be corrected when clinically appropriate, yet that does not establish that supplementation will prevent dementia. Cognitive health is influenced by cardiovascular risk, physical activity, education, social engagement, sleep, depression, hearing, smoking, diabetes and many other factors.

The sensible conclusion is therefore not “take vitamin D to prevent dementia”. It is that vitamin D status is one potentially modifiable part of a much larger healthy-ageing picture.

What makes this study different from typical nutrition headlines?

A major strength of the research is that it does not examine nutrition through a single lens.

The researchers combined dietary assessment, laboratory measurements of vitamin status and a dementia-risk prediction framework. That creates a more realistic picture of ageing because dementia risk is not determined by one laboratory number.

The CAIDE model itself is also important to understand. It estimates future dementia risk using several established risk-related characteristics; it does not diagnose dementia.

Therefore, a high CAIDE score does not mean an individual currently has dementia. It means that the person has a combination of factors associated with increased future risk.

This distinction is crucial for readers because memory lapses, slower recall and occasional forgetfulness are not automatically signs of dementia either.

Could fixing vitamin deficiencies improve cognition?

This is where the evidence becomes more nuanced.

Correcting a genuine nutritional deficiency is medically important. In some circumstances, deficiency-related neurological symptoms can improve when the underlying problem is identified and treated appropriately.

But correcting deficiencies is not equivalent to reversing established neurodegenerative disease. Dementia can arise through multiple pathways, including Alzheimer’s disease, vascular disease and other neurological conditions.

The Telangana study is observational and cross-sectional. Researchers measured participants at a particular point in time rather than following them for years to determine whether correcting deficiencies changed dementia outcomes.

That means the study cannot establish causation. It is possible that poor nutritional status contributes to cognitive-risk pathways, but it is also possible that broader health, socioeconomic or lifestyle factors influence both diet and dementia-risk scores.

Future longitudinal studies and controlled nutritional interventions will be needed to determine whether targeted correction of deficiencies can meaningfully reduce cognitive decline.

The hidden problem: eating enough is not the same as eating well

One of the most practical implications for Indian families is that older adults can become nutritionally vulnerable without appearing obviously undernourished.

Ageing can alter appetite, taste and smell. Dental problems may make certain foods difficult to eat. Chronic disease can restrict food choices. Medication use can influence appetite or nutrient absorption. Living alone can reduce motivation to prepare varied meals.

As a result, an older person may eat three meals a day and still have a diet that lacks variety.

The study’s dietary findings reinforce this point. The high-risk group did not simply differ in total calories or protein intake; differences were also observed in specific food groups and micronutrient intake.

This suggests that healthy ageing nutrition should focus on food diversity, nutrient density and overall dietary pattern, rather than simply counting calories.

What should families do with this information?

The findings do not justify indiscriminate use of multivitamins or high-dose supplements. Instead, they support a more structured approach to nutritional health in older adults.

• Encourage a varied diet containing vegetables, fruits, pulses, whole grains, nuts and seeds and appropriate protein sources.
• Include suitable sources of B vitamins and other micronutrients according to individual dietary preferences and medical needs.
• Pay particular attention to nutrition when an older person has poor appetite, weight loss or a restricted diet.
• Discuss laboratory testing with a healthcare professional when symptoms or risk factors suggest a deficiency.
• Do not treat memory problems as “normal ageing” if they are persistent or interfere with daily life.
• Manage blood pressure, diabetes, cholesterol and other cardiovascular risk factors because brain health is closely connected with vascular health.
• Maintain physical activity, adequate sleep and regular social and mental engagement alongside good nutrition.

A comparison worth remembering: supplement-first versus food-first thinking

The strongest strategy is usually not choosing one of these approaches in isolation. A healthy diet can form the foundation, while medically indicated supplementation can address specific deficiencies.

What the study means for India’s ageing population

India is entering a period in which the number of older adults will become increasingly important to healthcare planning. That makes prevention more valuable because dementia can affect not only individuals but also families, caregivers and health systems.

Nutrition offers an attractive prevention target because it is potentially modifiable. Unlike age or genetic susceptibility, diet quality can be changed. But turning that possibility into effective public health policy requires more than telling people to “eat healthy”.

Future programmes may need to identify vulnerable groups, improve access to nutritious foods, strengthen geriatric nutrition services and integrate nutritional assessment into appropriate primary-care settings.

The rural findings make this particularly relevant. If micronutrient deficiencies and dementia-risk factors cluster in populations with limited healthcare access, simply publishing dietary advice will not be enough. Intervention has to reach the people most likely to benefit.

What researchers should investigate next

The next step should be longitudinal research that follows people over time. Such studies could determine whether individuals with specific deficiencies are more likely to experience measurable cognitive decline and whether correcting those deficiencies changes outcomes.

Intervention trials would provide an even stronger test. Researchers could investigate whether improving dietary diversity, correcting vitamin deficiencies or combining nutritional interventions with exercise and cardiovascular-risk management produces measurable improvements in cognitive outcomes.

There is also an opportunity to develop Indian-specific approaches to dementia prevention. Dietary habits, socioeconomic conditions, vegetarian diets, food fortification, rural-urban differences and patterns of chronic disease can vary substantially from those in Western populations.

That is one reason the Telangana study’s India-specific risk framework is significant: dementia prevention cannot simply be imported from another population without considering local realities.

Bottom line: vitamins may be one piece of the brain-health puzzle

The ICMR-NIN research provides a valuable warning against treating cognitive ageing as purely a neurological problem. In a sample of 556 adults from Telangana, higher predicted dementia-risk burden was associated with poorer micronutrient status and less diverse dietary patterns, with vitamin D and several B vitamins emerging as important nutritional signals.

But the most responsible interpretation is also the most useful one: vitamin deficiency is a potential modifiable risk factor, not a proven single cause of dementia and not a standalone cure.

The bigger opportunity lies in identifying nutritional vulnerabilities early, improving diet quality and combining nutrition with established healthy-ageing measures such as physical activity and cardiovascular-risk management.

For families, the message is refreshingly practical. Brain health does not begin when memory problems become obvious. It is built over years through the interaction of food, movement, sleep, medical care and social life. As India ages, making those foundations stronger could become one of the most important investments in healthy longevity.