Fermentation benefits

Sizzling summers bring fatigue… but eating yogurt may revitalise you

Does a scorching hot summer sap your energy and leave you feeling tired and drained? Maybe you suffer from summer heat fatigue, a package of bothersome symptoms such as fatigue, loss of appetite, loss of sleep, stress, and lack of motivation. Some people even tend to catch a cold every summer. The problem is set to spiral as global warming takes hold and long hot summers become the norm.

But if for you summer spells trouble, you may find that eating a daily yogurt helps to alleviate the tiresome symptoms, according to this study from Japan.

Yogurt’s live bacteria may offer benefits

Summer heat fatigue is thought to be common and may be related to a disruption in the immune system, say the authors.

Yogurt contains live bacteria and previous research has shown that the immune system may be stimulated by consuming yogurt fermented with the lactic acid bacterium, Lactobacillus delbrueckii subsp. bulgaricus OLL1073R-1. In the elderly, yogurt made with this bacterial strain reduces the risk of catching colds and improves quality of life in areas of motivation, irritation, stress, and fatigue.

This yogurt might therefore be a promising candidate for combating summer heat fatigue, the authors reasoned.

They recruited 49 healthy men aged 30–49 years who felt fatigued every summer. The men were randomly assigned to receive a 100mL bottle of either yogurt or a placebo (milk with added lactic acid) every day for 12 weeks leading up to early autumn. They were asked to score their symptoms on a visual scale.

Yogurt was associated with reduced fatigue symptoms

After 12 weeks the scores for general malaise, fatigue, feeling languid and stress were all lower in the yogurt group compared with those having placebo. The scores also showed the participants in the yogurt group felt less languid, tired, and stressed at the end of the study than they did before starting their daily yogurt routine.

The study also showed that he autonomic nervous system which is responsible for many functions in the body appeared improved in the yogurt group, from six weeks after starting the trial until the end of the trail.


‘Yogurt may tune the balance of the autonomic nervous system and relieve the physical and mental disorders induced by seasonal changes.’ – Makino S et al, 2018.

How might yogurt achieve this effect?

Yogurt may achieve these benefits in summer heat fatigue through a variety of ways. This strain of lactic acid bacterium produces high levels of a carbohydrate, exopolysaccharide, and the authors suggest this may have numerous impacts including an effect on the immune system and antioxidant activity. However, in this study they measured levels of an immune marker and found no marked difference between the group receiving yogurt and the placebo group.

Further studies are therefore needed to confirm these findings and to determine whether summer heat fatigue is indeed connected with a disruption of the immune system, the authors conclude.

‘These findings provide new insights into the health-promoting effects of yogurt fermented with L. bulgaricus OLL1073R-1.’ – Makino S et al, 2018.

Find out more: read the original article.

Source: Makino S, Hemmi J, Kano H et al. Anti-fatigue effects of yogurt fermented with Lactobacillus delbureckii subsp. bulgaricus OLL1073R-1 in healthy people suffering from summer heat fatigue: a randomized, double-blind, placebo-controlled trial. Nutrients. 2018 Jun 21;10(7).pii:E798.

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