By Jill Max, HealthAtoZ contributing writer
Nuts used to be forbidden fruit for people following a heart healthy diet. But no more. Walnuts, almonds and other nuts have been shown to help lower cholesterol, and a recent study found that pecans, an American favorite, are a powerful nut in the pack.
The study, published in the Journal of Nutrition, found that adding 2 ounces of pecans a day to the low-fat, heart-healthy diet recommended by the American Heart Association (AHA) lowered cholesterol levels more than the diet alone.
The AHA's low-fat Step 1 diet recommends that healthy individuals limit their cholesterol intake to 300 mg and those with heart disease to less than 200 mg. (The average man consumes 337 mg of cholesterol/day, and the average woman consumes 217 mg cholesterol/day.)
The pecan diet worked better than the AHA diet because it not only lowered total cholesterol and LDL cholesterol (the so-called "bad" cholesterol) more, but it also lowered triglycerides and raised HDL cholesterol levels (the "good" cholesterol). The AHA diet by itself tends to lower HDL and raise triglycerides, other fats in the blood.
"The general public considers nuts to be a high-fat food, so they tend to avoid it," says Sujatha Rajaram, Ph.D., assistant professor in the department of nutrition at Loma Linda University and lead author of the study. "But we know that frequent consumption of nuts can lower heart disease."
There have been other studies on the effects of nuts on cholesterol levels. Many also have concluded that nut-rich diets significantly improve cholesterol. What makes the pecan study unique is that it shows that eating nuts can affect more than just cholesterol.
"Most of the time we focus on cholesterol, but we have shown that eating pecans also lowers triglycerides," Rajaram said. "Independently of cholesterol levels, if someone has high triglycerides, it's also a risk factor for heart disease."
A little goes a long way
The study looked at 23 subjects, all of whom followed both the Step 1 diet recommended by the AHA to lower cholesterol and a diet rich in pecans for four weeks each. Those following the pecan diet ate portions 20 percent smaller than those following the AHA diet, so they were eating the same number of calories. All food was prepared and weighed at a university laboratory. "In order for us to show clearly that it was the pecans, we had to control for weight," Rajaram explains. Otherwise, if subjects lost weight, their cholesterol levels would automatically go down.
The pecan diet lowered total cholesterol by 6.7 percent, LDL cholesterol by 10.4 percent, and triglycerides by 11 percent compared with the Step 1 diet. Every 1 percent reduction in LDL cholesterol translates into a 1.5 percent reduction in coronary heart disease, suggesting that the pecan diet lowers heart disease risk by 25 percent.
But aren't nuts fattening?
It's one thing to eat a carefully prepared calorie-counted diet, but what happens if you just add nuts to what you're already eating?
Nuts are relatively high in calories and fats. However, they contain mostly unsaturated fat. Unsaturated fats can help control blood cholesterol levels and, thus, lower the risk for heart disease. Because many Americans eat too much saturated fat, nutrition experts recommend substituting saturated fat with the unsaturated kind, such as polyunsaturated fats found in walnuts, and monounsaturated fats, found in pecans.
Also, nuts contain numerous other substances besides unsaturated fats that could lower cholesterol. It could be the high fiber found in nuts or their phytonutrients, which have anti-oxidant properties that may help lower cholesterol, according to Rajaram.
While nuts can be fattening, they can be healthy and nutritious if eaten in moderation.
"We believe that just by adding nuts to your diet, you would see a reduction in cholesterol," Rajaram says. She also believes that if you include nuts, you will automatically eat less of other foods because nuts are satisfying.
Of course, that may be easier said than done. "A person will have a difficult time adjusting their calorie level," says Gail Frank, Ph.D., R.D., professor of nutrition at California State University at Long Beach and a spokeswoman for the American Dietetic Association.
Frank says that many people wanting to add nuts without increasing calories may benefit by advice from a registered dietitian.
That doesn't mean, however, that adding nuts isn't a good way to lower cholesterol. "To me, the good news is that we can affect change with eating habits," Frank says. "The bad news is that it may not be easy to stick to."
Just add nuts
Nuts are versatile, so it's easy to incorporate them into your diet. Two ounces is just a handful, so use them sparingly. Rajaram suggests the following:
- Make a smoothie using fruit, nuts and milk.
- Add nuts to your main course by substituting them for a portion of the meat. For instance, you could make meatballs by replacing half of the meat with ground nuts.
- Grind them in sauces or gravies.
- Use them in toppings for everything from oatmeal to green beans.
- Make tasty snacks by mixing nuts and dried fruit.
This article was reviewed and updated June 2007.
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