Does Vitamin D Affect Alzheimer's Risk or Progression?

Vitamin D plays an important role in our health. It helps the body absorb and retain calcium. Calcium helps the body build strong bones. Vitamin D also helps the body fight inflammation, cancer cells, and infections. Some doctors believe it helps reduce the risk of Alzheimer's and other forms of dementia. But the evidence is mixed.1,2

The Alzheimer's Association sponsored a large study published in 2023. This study found that vitamin D supplements seemed to consistently lead to longer dementia-free years. Taking vitamin D supplements was linked to a 40 percent lower dementia risk. This was compared to people who did not take extra vitamin D.2

The study also found that vitamin D benefited:2

  • Women more than men
  • People with normal thinking and problem-solving (cognitive) skills more than people who already had mild cognitive issues
  • People with a genetic marker linked to Alzheimer's more than people without the marker

However, another large study found just the opposite. This study was published in 2022. It concluded that:3

  • Vitamin D worsened existing Alzheimer's disease
  • Older people without dementia had a higher risk of developing Alzheimer's than those who did not take the supplements

Some of the variations in study results may be that there are different types of vitamin D supplements. The most common are D2, D3, and a D-calcium combination.2

How to get more vitamin D

Vitamin D is both a nutrient we eat and a hormone our bodies make naturally. Vitamin D supplements come in 2 forms:1

  1. D2 (ergocalciferol)
  2. D3 (cholecalciferol)

Generally, D3 is linked to greater health benefits than D2.1,2

Your body makes vitamin D when you are exposed to sunlight. This is why it is sometimes called "the sunshine vitamin." If you need more of this vitamin, your doctor may suggest you go outside for a few minutes daily. However, this is not always possible due to weather and other constraints.1

It can be hard to get enough vitamin D through eating, which is why supplements are common. Foods that contain vitamin D include:1

  • Fatty fish such as salmon, swordfish, sardines, and tuna
  • Cod liver oil
  • Foods with added vitamin D such as orange juice, dairy and plant milks, and cereals
  • Beef liver
  • Egg yolk

Other nutrients may help with Alzheimer's too

Other nutrients are more consistently and strongly linked to reducing the risk of dementia. B complex vitamins, especially folic acid, seem to delay or prevent Alzheimer's and other forms of dementia.4

Folic acid is also known as B9 or folate. It is found in:5

  • Dark green leafy vegetables like turnip greens, spinach, romaine lettuce, asparagus, Brussels sprouts, and broccoli
  • Beans, peanuts, and sunflower seeds
  • Fruit
  • Whole grains
  • Liver
  • Eggs

Ascorbic acid and vitamin E may also help lower the risk of dementia. But studies are not strong enough to support taking supplements.4

More research is needed to understand how vitamin D may be linked to dementia. In any case, vitamin D is still vital for overall health. Your doctor can help you decide whether vitamin D supplements are right for you.1

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