When it comes to health, it’s rarely the most expensive items that do us the most good, sometimes it’s as simple as regular consumption of cheap fruit and vegetables. This week’s Nutrition News looks at a number of recently published studies and uncovers how kiwis and tomatoes, some of the cheapest fruits in the greengrocers, can support our health.

The health benefits of kiwis

Originating from China, the kiwi is a unique fruit known for its distinct brownish or golden exterior and soft, green or yellowish interior.

One of its most remarkable features is its exceptional vitamin C content, placing it among the top fruits for vitamin C. A mere 100 grams of kiwi provides approximately 100 milligrams of vitamin C, surpassing the daily recommended intake.

The fruit, according to the article “Rich in iron and vitamin C: What you should know about kiwis” derives its name from the kiwi bird of New Zealand, as its external colour bears a striking resemblance to the bird's plumage. Interestingly, the yellow kiwi strain gaining popularity in Israel was developed in New Zealand, adding to the fruit's global appeal.

Beyond its vibrant taste and vitamin C, the kiwi boasts other nutritional benefits, serving as an excellent source of iron and calcium. Despite its petite size, one kiwi averages around 60 calories, making it an ideal low-calorie snack. Additionally, the kiwi stands out for its extended freshness compared to other fruits, retaining its nutritional value over time, making it a convenient and healthy dietary choice.

The kiwi is a delicious yet often overlooked fruit given its nutritional profile, packed with essential vitamins and minerals. From its unique flavour to its impressive nutrient profile, the kiwi earns its status as a versatile and health-conscious choice.

The link between the microbiome and skin health

The skin microbiome, composed of microorganisms inhabiting the skin, emerges as a key player in understanding the ageing process, according to research from the Centre for Microbiome Innovation at the University of California San Diego and L’Oréal Research and Innovation, published in the article “Healthy microbiome plays a role in skin aging, researchers say” by Medical News Today. Analysing data from 13 L’Oréal studies involving over 1,000 female participants aged 18–70, the researchers identified a correlation between skin microbiome diversity and crow's feet wrinkles, a common sign of ageing. The study also found a negative association between microbiome diversity and transepidermal water loss, indicating a connection between microbiome balance and skin hydration.

Notably, specific microbial taxa were linked to the severity of crow's feet wrinkles, independent of age. The research opens avenues for further exploration into the role of these microbes in wrinkle development and their interactions with skin cells. Dr. Se Jin Song, the director of research at UC San Diego's Centre for Microbiome Innovation, emphasised the need to investigate whether these microbes influence skin cells, affect other microbiome members, or produce compounds beneficial for skin appearance.

The study marks a significant step toward understanding gut health and, specifically, the microbiome's impact on skin health and ageing. Dr. Shilpi Khetarpal, a dermatologist at the Cleveland Clinic, noted that the microbiome's balance can influence transepidermal water loss, akin to a grape transforming into a raisin. Considering the microbiome's role in responding to environmental factors, such as the sun and pollution, it becomes evident that skin microbiome balance directly affects the ageing process.

The connection between gut health and skin health is gaining attention, with research indicating that the gut and skin microbiota collaborate to combat pathogens, reduce inflammation, and regulate the immune system. Dr. Khetarpal highlighted the evolving focus on the skin microbiome, contributing to our understanding of conditions such as acne, rosacea, and ageing. The study's identification of microbial markers and ageing signs provides a foundation for future research and the potential development of personalised skincare solutions leveraging the microbiome.

How tomatoes could support heart health

A recent study, reported in the article “Can eating more tomatoes daily help lower high blood pressure” suggests that incorporating tomatoes into the diet may help manage and reduce the risk of hypertension in older adults with mild high blood pressure, leading to supported heart health.

 The research, published in the European Journal of Preventive Cardiology, involved 7,056 participants, 82.5% of whom had hypertension. Those who consumed the most tomatoes or tomato-based foods experienced a 36% lower risk of developing hypertension compared to those who consumed the least. In individuals with existing high blood pressure, particularly stage 1 hypertension, moderate tomato consumption was linked to a reduction in blood pressure.

The study categorised participants based on daily tomato consumption: less than 44 grams, 44–82 grams, 82–110 grams, and more than 110 grams. Higher levels of tomato consumption were associated with lower diastolic blood pressure, indicating the pressure in arteries when the heart is at rest. Individuals with stage 1 hypertension and intermediate tomato consumption also showed reduced systolic and diastolic blood pressure compared to those consuming fewer tomatoes.

Lycopene and potassium are identified as key compounds in tomatoes that contribute to their potential protective effects against hypertension. Lycopene, a carotenoid in tomatoes, may reduce the production of angiotensin-converting enzyme and promote nitric oxide generation, aiding in blood pressure regulation and improved blood flow. Potassium helps balance sodium levels, regulate fluids, and support lower blood pressure.

While the study did not delve into the impact of tomato preparation methods, the lead researcher, Dr. Rosa María Lamuela-Raventós, suggested that cooking tomatoes may enhance the bioavailability of beneficial compounds. The study opens doors for further research into the specific mechanisms through which tomatoes influence blood pressure and whether other fruits and vegetables with similar properties can contribute to cardiovascular health. However, individuals taking ACE inhibitors for hypertension should consult their physician regarding potassium intake and potential interactions.

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Alison Astill-Smith author Alison is Director and Founder of Metabolics who writes about Metabolics updates, events and natural healthcare. Her experience and passion for natural supplements and healthcare comes from her years of experience as a practising osteopath, having founded Metabolics in her search for high quality, natural products in her own work. Alison has been a qualified and practising Osteopath since 1981 and regularly gives seminars on a range of healthcare subjects to the wider practitioner community helping share her knowledge and experience.