I came across a blog on nectarines recently which really annoyed me. My kids would say ‘Mom is triggered, keep away’. As an aside, I do find it interesting that after decades of meditation and mindfulness, there are still some seemingly innocuous things that can trigger me.
So what was the problem?
The problem was that the blog claimed that nectarines had 'oh so very many' health benefits and even provided a long list of references.
The problem behind the problem was the fact that the references only vaguely related to the subject matter. It was a prime example of what is called the ‘if this is true, then that must also be true’ syndrome. Ok, I just made that term up, but let me explain.
I am familiar with this concept as it plays out at family dinner on a regular basis.
‘If greens are good for me, then a Big Mac has lettuce and must be good for me too’.
There is also an adult version for ex-patriates living in developing countries.
‘If quinine has anti-malarial properties, then a large bottle of boot-legged gin with some tonic (and maybe even some lemon for extra health points) must be good for me’.
I lived in Africa for ten years and heard that big lie on numerous occasions.
Another twist on this flawed logic would be thinking that if sugar is not so good for our health, and if fruit contains sugar, then fruit must be unhealthy. This type of thinking overlooks the fact that sugar in fruit is packaged in a very different way to sugar in fruits. Sugar is fruits comes co-packaged with fibre which reduces the absorption of the sugar.
The worst part for me is the fact that the blogger in question implied that the science in the references related specifically to nectarines. It is only when you look at the references that you see the problems. The references relate to fibre, vitamin C and anti-oxidants in general terms but not nectarines.
This type of generalization and extrapolation is faulty. I guess the blogger knew that most people just skim the headlines but don’t have time or interest to read the backroom data.
Why would a blogger do this?
I can only assume that this was a ghost-writer who was paid by the word or had a specific word count to meet.
Let’s look at the actual direct science behind nectarines. No fluff.
What Are Nectarines?
Nectarines (Prunus nucipersica) are members of the Rosaceae family. They are similar to peaches but not identical. You can tell the difference between peaches and nectarines by the presence or absence of hair. Peaches have fuzzy hair.
Nectarines are fuzz-free. In fact, nectarines look like peaches that have had some treatment with the much advertised NO NO hair removal device.
Nectarines are believed to have originated in China over 2000 years ago.
Nowadays, California is the leading producer in the US.
There are over 100 varieties of nectarines.
Overall, nectarines can be classified as freestone or clingstone (depending on how the flesh relates to the stone) or they can be classified as white-flesh or yellow-flesh.
Peaches and nectarines are the second most important fruit crop in Europe with a combined production of 4.1 million tons per year (1).
The average content of a 140 gm serving of nectarines is:
- Calories 70 kcal
- Calories from fat 5 kcal
- Carbohydrate 16gm
- Fiber 2gm
- Sugar 12gm
- Protein 1gm
- Vitamin A 4% RDA
- Vitamin C 15% RDA
- Iron 2% RDA (2).
Amazon sells dried nectarines at a cost of 2 USD per ounce. A quick check on prices are WholeFoods shows that nectarines and peaches cost the same - $3.99 per pound.
Is There Any Research?
There are 236 publications relating to nectarines but no clinical trials. To put this into context, there are over 1700 publications on blueberries which includes 71 clinical trials.
Do They Enhance Longevity?
Nectarines were studied as potential longevity agents in a fruit-fly model in a US based study in 2011 (3). The fruit-fly has a short lifespan which makes it a popular choice for longevity studies.
After all who would want to pin their career on longevity studies in a species whose life expectancy is greater than that of a human? In the scientific world which is ruled by the adage of ‘publish or perish’, the researcher would likely literally ‘perish’ before some animal studies on longevity would reach their end-point.
Fruit-flies are also a cheap date as they like a simple diet and they give a whole new dimension to the concept of portion control.
The study reported inconsistent results with reduced lifespan for women fed 4% nectarine extract but not in the male flies. The study does not make a big deal out of it but does report increased ‘fecundity’ (aka fertility) in the nectarine arm of the study.
There is no proof that nectarines have any meaningful effect on life-expectancy.
Do They Improve Digestion?
Standard blog logic says that nectarines have fibre. Fibre is good for digestion. Therefore, nectarines are good for digestion. The direct scientific literature on this is limited but there is one study worth looking at here.
Diacylyceride acyltransferase is a key enzyme involved in the synthesis of dietary triglycerides (a form of lipid). Triglycerides are known to be a risk factor for heart and metabolic disease.
In a 2015 publication, 90 overweight and obese study subjects received a range of investigational agents including grape extract, apple peel extract, nectarine/apricot extract, raspberry extract or placebo over a 7 day period (4).
It is worth noting that the study says that it used apricot/nectarine but does not specify whether they used apricot or nectarine or a combination of both.
All of the investigational agents (except placebo) blocked the activity of the diacylglyceride acyltransferase enzyme in a laboratory based model. Either way only the grape extract actually reduced the formation of triglycerides after ingestion of a high fat meal in humans.
Nectarine extract looked promising in a laboratory model but did not actually reduce blood levels of lipids in humans.
Do They Stabilize Blood Sugar?
A large analysis evaluated the association between certain fruits and the risk of diabetes from three trials (5). They found that some fruits eg blueberries, grapes and apples were associated with a lower risk of diabetes. Unfortunately the study did not look at nectarines.
There is no scientific evidence to suggest nectarines stabilize blood sugar.
Does Nectarine Fight Free Radical Damage & Inflammation?
An interesting study measured the vitamin C, carotenoid and phenolic content in white and yellow flesh nectarines (6).
As a generalisation the yellow flesh nectarines had higher levels of vitamin C and carotenoids but lower levels of total phenolics. The main contributor to antioxidant activity was the phenolic content. Regardless of this detail the nectarines were noted to have antioxidant capabilities.
Another study found that nectarines had high levels of phenolics and flavonoids which in turn had antioxidant activity (7).
The Maillard Reaction is the term given to the reaction between amino acids and sugars and is responsible for the browning of some fruits and vegetables. Researchers from Spain found that microwaving nectarines released compounds which in turn inhibited polyphenol oxidase activity and prevented browning of peaches (8).
Nectarines contain vitamin C and anti-oxidants but have not been proven to have clinical benefits in humans.
Do They Treat Cancer?
A National Institutes of Health study co-ordinated by the University of Illinois, Chicago, studied the relationship between fruit and vegetable consumption and the risk of lung cancer (9). This was a huge study with almost half a million study participants.
With all those data points, the study had lots of conclusions and observations. Of relevance to us, nectarine consumption was inversely associated with lung cancer in men ie men who ate nectarines were less likely to get lung cancer.
Does this mean that if you start eating nectarines, you're less likely to get lung cancer? No. This is a curious correlation and nothing more, as far as nectarines go.
Epidemiological studies have shown that people who eat nectarines happen to be less likely to get lung cancer. It does not show that it treats or prevents lung cancer.
Do They Boost Immune System?
There are no studies here which means that we have to conclude that there is no evidence that nectarines help with immunity.
Do They Promote Weight Loss ?
The usual blogger logic here would be that nectarines have fibre and fibre can help you lose weight. A search for nectarines and 'weight loss' or 'obesity' or 'BMI' drew a blank.
There is no direct proof that nectarines help with weight loss.
Do They Enhance Eye Health?
We have the same issue here. Standard blogger logic says that nectarines are good for eye health because they contain vitamin A and lutein. A search for nectarines and 'ocular' or 'eye' or 'retinal' drew a blank.
There is no direct proof that nectarines help with eye health.
Do They Improve Cardiovascular Health?
Same again. Theoretically, nectarines have vitamins, potassium, fibre and polyphenols and so should be good for our heart health. However, there are no studies proving this.
There is no direct proof that nectarines help with heart health.
Are Nectarine Safe?
Nectarines feature on the dirty dozen which is a list of foods considered to be problematic by the Environmental Working Group (9). This is a non profit organization that advocates for pesticide free healthier foods.
This does not mean that we need to avoid nectarines but does mean that we should buy organic or at least wash or peel them before eating.
Polish doctors wrote up a case of near fatal anaphylactic reaction to nectarines in an elderly man (10). The man had a life-long known allergy to peaches. Due to impaired sight, he had inadvertently eaten nectarines approximately 30 minutes before the incident. This case report highlights the possibility of cross-allergies among fruits.
People who are allergic to latex can have cross allergies to fruits including nectarines (12).
There is a very interesting clinical entity called ‘food dependent exercise induced anaphylaxis’ whereby the combination of trigger foods and exercise can induce anaphylaxis (13). Emerging data confirms that nectarines are one of the potential trigger foods in susceptible people.
Australian doctors solved the puzzling case of a 67 year old lady who was re-admitted to hospital with gastrointestinal symptoms (14). She failed to settle with conservative management.
CT scans revealed intestinal obstruction and a nectarine stone was removed during open surgery. It emerged that the stone was not only causing obstruction but had also perforated the bowel. The lady had no memory of swallowing the stone.
Californian nectarines were found to be contaminated with the bacteria, listeria, in 2014 (15).
During a nationwide recall of nectarines for Listeria contamination, a 68 year old man developed Listeria spontaneous bacterial peritonitis (a life threatening complication of severe liver disease) which was thought to relate to nectarine consumption (16).
There is really no credible research on nectarines. I am not anti-nectarine in any way. I just feel that readers of Healthy But Smart already know about the food pyramid and don't need me to point out the obvious fact that fruits are good for you.
The fact that fruits are good for you is not the same as saying that nectarines have been specifically shown to have dedicated health benefits. Why do I care? Truth is that I care because I know the lengths people will go to and the financial sacrifices that they will make for their health.
Sometimes, there is specific proof that a certain food does a certain thing and helps us in a certain way. In that case, you may well want to source it and buy it. We, at Healthy But Smart, want to be your signpost to help you find these items.
However, as things currently stand, nectarines cannot claim celebrity for anything except being a delicious fruit.