Nuts are an integral part of Christmas food but how healthy are they to eat all year round?
The answer comes down to understanding what makes a nut healthy and how much do you need to eat in order to enjoy their health benefits?
What is a nut?
According to Wikipedia, “culinary nuts are dry, edible fruits or seeds, usually, but not always, with a high fat content. Nuts are used in a wide variety of edible roles, including in baking, as snacks (either roasted or raw), and as a flavouring”. 1
- True, or botanical nuts: dry, hard-shelled, uncompartmented fruit that do not split on maturity or release seeds e.g. acorns, chestnuts, hazelnuts etc.
- Drupes: fleshy fruit surrounding a stone, or pit, containing a seed e.g. almonds, cashew, coconut, pecans, pistachio and walnuts.
- Gymnosperm seeds: naked seeds, with no enclosure e.g.pinenuts.
- Angiosperm seeds: unenclosed seeds within a larger fruit e.g. peanuts
What is their nutritional value?
Nuts are very nutrient dense containing some protein, fat (particularly polyunsaturated fat), dietary fibre, calcium, vitamins and minerals. However they are also high in energy. This makes them very appropriate as a snack for people of normal body weight, however care does need to be taken if people are overweight or obese.
Do you eat a handful of nuts (50g) as a snack or just one or two a day?
Often foods are held up to be good food sources of certain nutrients and so the diagram below compares nuts with similar amounts of other foods that are good food sources of the nutrient concerned. If you are at a healthy body weight or would like to gain weight then nuts are a good source of energy, protein, fat, polyunsaturated fat, dietary fibre and calcium and are low in sodium.
If you are overweight or obese then please note the energy value of nuts. In the place of nuts better sources of these nutrients are as follows:
- Protein – meat, tuna and trim milk®
- Fat – trim milk®, tuna, beef, margarine
- Calcium – trim milk®
- Dietary fibre – bran cereal
Diagram 1: The nutrient content of nuts compared to average servings of other common foods
What are the health benefits of nuts?
Here are just a few of the results from studies showing that tree nuts (almonds, Brazil nuts, cashews, hazel nuts, macadamia, pecans, pine nuts, pistachios and walnuts) are healthy to eat.
A study that looked at 13,292 men and women (19+years) participating in the 1999-2004 National Health and Nutritional Examination Surveys (NHANES) found over a 24hour recall period, those participants who consumed unsalted tree nuts > ¼ounce /day experienced the following benefits:
- 5% lower prevalence of metabolic syndrome (the name given to a group of risk factors that occur together and increase the risk for coronary artery disease, stroke and Type 2 diabetes.2
- Lower levels of C-reactive protein, a marker for inflammation which is associated with atherosclerosis and artery disease.3
- A lower prevalence of:
- abdominal obesity
- high blood pressure
- high fasting glucose (blood sugar)
- low high density lipoprotein-cholesterol levels (i.e. ‘good cholesterol’)
The NHANES study2 concluded that the benefits were greatest when nuts were eaten as part of a healthy diet that included:
- Whole grains
- Less saturated fats
- Low salt
- Fewer calories from solid fats, alcohol and added sugars2
NOTE: these benefits were achieved with only > ¼ ounce nuts /day
Researchers at Andrews University have found that students who had eaten walnuts daily as one of the main ingredients in banana bread performed better on tests that measure inferential reasoning i.e the ability to judge the accuracy of statements made when reading an article, paper or other source.4
Protecting bone health
Walnuts may also decrease the breakdown of bone. One study in Penn state found that higher consumption of the essential fatty acid alpha-linolenic acid (ALA), that is plentiful in walnuts, leads to a reduction in bone turnover, and a shift in the balance of bone degradation/ formation towards formation.4
Walnuts rank above peanuts, almonds, pecans, pistachios and other nuts as they contain almost twice as many antioxidants. Only 7 walnuts a day are needed to enjoy the health benefits.5
Studies have considered the role of nuts in weight control offering several reasons why the regular consumption of nuts may not result in weight gain. Here are some of those reasons:
- Nuts are high protein and fibre and have a low glycaemic index. These factors along with their crunchy nature stimulates, during chewing, hormones like cholecystokinin which aid satiety.
- Nut consumption may lead to an increase in energy expenditure as the high unsaturated to saturated fat ratio in nuts may increase resting metabolic rate (RMR).
- Some research suggests that despite their high fat nature the fat found in nuts may not be highly bioaccessible. Meaning that some fat may be lost in faeces rather than being available as an energy source.
With these things in mind one research project compared the consumption of hazel nuts with other high fat snacks (chocolate and potato crisps) on the health of 118 non obese subjects. They looked at body weight and composition, blood lipids and lipoproteins, RMR, appetite indicies and diet quality. Interestingly after 12 weeks they found no difference in the outcomes measured between groups except for diet quality which was significantly higher in the nut group despite the fact that weight was maintained.6
Problems associated with nut research
Although there are many studies supporting the benefits of nuts these are often flawed by the methodology used. Often sample sizes are small or over short duration. Body weights are often self reported, recruitment methods are seldom randomized and studies can be financed by industrial companies such as Hershey or nut producers.7
Recommendations for use
- For those people who are of a healthy body weight the use of nuts as a snack or in salads or main meal dishes should do no harm (unless of course you have a allergy to nuts).
- People who have very high energy needs such as athletes or workers involved in physically demanding occupations will find nuts a healthy addition to their diet.
- If overweight or obese then limit nuts to ¼ ounce per day e.g. 2 brazil nuts each day will confer health benefits plus help you to meet your daily needs for selenium.
- Use nuts as part of a healthy diet as outlined in the NHANES study.
- If you are having 3 red meat ( e.g. beef, pork or lamb), 2 white (e.g. fish or chicken) and 2 non meat meals ( e.g.vegetarian dishes such as based on egg, cheese, bean or lentils) per week then the nuts could be included in the non meat meal dishes. See our recipe for Spinach and walnut lasagna.
- O’Neil CE, Keast DR , Nicklas TA, Fulgoni VL, 111,2011. Nut consumption is associated with decreased health risk factors for cardiovascular disease and metabolic syndrome in U.S adults:HNANES 1999-2004. J Am Coll Nutr. 30:502-510.
- O’Neil CE, Keast DR, Fulgoni VL, Nicklas TA, 2010. Tree nut consumption improves nutrient intake and diet quality in US adults:an analysis of National Health and Nutritional Examination Survey (NHNES) 1999-2004. Asia PacJ CLin Nutr.19(1):142-150.
- Leong K, “Will eating walnuts give you more brain power?” Yahoo News. Sept 28,2011 http//voices.yahoo.com/will –eating-walnuts-give-more-brain-9157073.html?cat=5
- 7 Walnuts a Day Deliver Health Benefits,” Health News, March 28,2011. http://www.upi.com?Health_News/2011/03/28/7-walnuts-a-day-deliver-health-benefits?UPI-93441301365744/.
- Tey Sl, Brown R, Gray A, Chisholm A, Delahunty C, 2011. Nuts improve diet quality compared to other energy-dense snakcs while maintaining body weight. Journal of Nutrition and Metabolisk.doi:10.1155/2011/357450
- What are the health effects related to consumption of nuts? 2012 USDA Evidence Analysis Library. Printed on:06/23/12