It’ll take more than an apple a day to keep the doctor away, but your diet can help keep disease at bay. It seems like almost every month a new scientific study shows the health benefits of certain foods.

The following foods have repeatedly been shown to be good “brain foods.” They contain specific antioxidants and other nutrients that may protect our brains from the effects of aging, keeping our minds keen and our memories sharp for as long as possible. Best of all, they don’t have to bust your grocery budget…

1. Berries

A study published last month in the Annals of Neurology is just the latest evidence of the health benefits of berries. This study found that eating more than one serving of blueberries a week and more than two servings of strawberries a week could delay cognitive aging – meaning a decline in skills like thinking, reasoning, and memory – by up to two and a half years.

Berries have a high level of antioxidants called anthocyanidins, which are unique in that they can cross the blood-brain barrier and tend to locate in the areas of the brain responsible for memory and learning.Raspberries, cherries, elderberries, red grapes, and concord grapes also contain anthocyanidins.

Shopping tip: Check your supermarket’s or wholesale club’s frozen isle for frozen berries, which are cheaper than fresh produce. I put frozen blueberries from BJ’s Wholesale Club in my oatmeal. Frozen berries also make great smoothies: Just add yogurt, plus water or milk to make it thinner or ice to make it thicker.

2. Turmeric

Numerous studies suggest that this curry spice (see photo) can slow the progression of Alzheimer’s Disease, a degenerative brain disorder that leads to death. (Check out 5 Tips That May Prevent Alzheimer’s Disease for more.) Turmeric contains an antioxidant called curcumin, which has been found to inhibit the growth of a type of plaque that accumulates in the brains of people with Alzheimer’s, according to Oregon State University.

Shopping tip: Think yellow. Turmeric may be in foods you already eat. My father, a cardiologist, eats liquid eggs from a carton. When I recently asked him why he switched from the AllWhites brand (which is 100 percent egg whites) to a supermarket house brand (which tries to resemble real eggs), he said he’d discovered that the supermarket brand contains turmeric – that’s how they gave them a yellow color without adding yolk. Some mustard brands also contain turmeric.

3. Cold-water fish

Reinforcing existing evidence of the health benefits of fish, a UCLA study published in February showed that a diet poor in omega-3 fatty acids may cause the brain to age and literally shrink faster. This was especially true of the omega-3 called docosahexaenoic acid, or DHA, which is found in fatty fish that live in cold waters:anchovy, bluefish, herring, mackerel, menhaden, mullet, salmon, sardines, sturgeon, trout, andtuna, says the National Institutes of Health. If you’re a vegetarian, try seaweed instead.

Shopping tip: Don’t forget to check your local wholesale club, where fresh cuts are usually cheaper than at the supermarket. And consider other forms. For example, frozen salmon burgers may be cheaper than fresh salmon, and canned tuna is cheaper than fresh tuna.

4. Avocados

If you don’t like fish, don’t worry. Avocados contain more omega-3′s than any other fruit, according toUCLA‘s Brain Research Institute.

Shopping tip: As we reminded you in 30 Tips to Save on Food, produce is cheapest when it’s in season. In California, where 90 percent of U.S. avocados are grown, the season runs from March through September, according to the California Avocado Commission.

Karla Bowsher runs our deals page and covers consumer, retail, and health issues. If you have a comment, suggestion, or question, leave a comment or contact her at karla@moneytalksnews.com.