Bilberries and lingonberries – health effects and health claims

The new Nordic Nutrition Recommendations (NNR), launched in June 2023, clearly states that berries, along with fruit and vegetables, are part of a healthy and sustainable diet. The recommendation is that we should eat 500 - 800 g of vegetables, fruit and berries per day. There is also great interest in developing new, innovative, healthy and sustainable products from Swedish forest berries. For example, FINEST has studied the potential of malolactic fermentation to reduce the acidity of juices from lingonberries and bilberries. It is therefore interesting and relevant to take a closer look at what we know about the health effects of Swedish forest berries, such as lingonberries and bilberries, and what food companies are allowed to say about berries health effects in labeling and marketing to consumers.

Berries – part of a healthy diet 

Recommendations to eat a lot of vegetables, fruits and berries are based on the fact that these food groups contribute to the intake of essential nutrients, plus epidemiological studies have shown associations between higher intakes of these food groups and positive health outcomes, notably lower incidence of certain cancers, cardiovascular diseases and premature death. The recommendations refer to these food categories as a whole and there are no recommendations on how much we should eat of specific berries, fruits or vegetables. The scientific literature also discusses that berries may have other health benefits, such as positive effects on gut microbiota, the immune system, vision and cognition.

Possible mechanisms

A general limitation of epidemiological studies is that they need to be complemented by mechanistic and/or controlled studies in order to prove causality. For berries, there are several possible mechanisms that can explain long-term positive health effects. These may include mechanisms linked to the low energy content of berries or their content of fiber, vitamins and other bioactive substances (read more in the article by Rosell och Fadnes, 2024).  Many substances in berries, both vitamins and other substances, act as antioxidants. However, it has been difficult to demonstrate the health effects of individual antioxidants. Instead, it is likely to be a combined effect, arising from the natural mixture of substances. However, the possible synergistic effects between different bioactive substances in berries (or other plant-based foods) are not yet fully understood. In the discussion on antioxidants, it is important to underline that antioxidative capacity demonstrated in vitro (in test tubes) does not automatically mean a positive health effect in the body. Similarly, one should be cautious about drawing strong conclusions about health effects in humans based only on results from animal models. To be more confident about the health effects of specific berries in humans, one should primarily rely on controlled studies on humans who have eaten the berry of interest. If you are interested in health effects in healthy people, you should also be careful when interpreting results from studies on patients, i.e. people with disease.

Bilberries or blueberries?

When discussing the health benefits, it is important to distinguish between Nordic wild bilberries (Vaccinus myrtillus) and American blueberries. In Swedish they are both called "blueberries" (sv. blåbär), which easily leads to confusion as to which berry is meant. Nordic bilberries have a dark, blue-red flesh, while the flesh of American cultivated blueberries is much lighter, usually yellow-white. Among other things, Nordic bilberries contain more anthocyanins (a group of polyphenols), which give the flesh its characteristic blue-red color and are often believed to have positive effects on the body. In scientific studies, the Latin name is usually given, to further clarify which berry it is. There are generally more studies with American blueberries than with Nordic bilberries.

Few studies on bilberries and lingonberries 

In the spring of 2023, FINEST conducted a literature screening to better understand which health effects of Nordic wild bilberries and lingonberries have been scientifically studied in controlled studies in healthy people. The screening was limited to studies on whole (fresh or processed) lingonberries or blueberries and studies on pressed cake, powder or juice of lingonberries or bilberries. Studies with mixtures of lingonberries/bilberries and other berries, leaves, extracts or pure substances from lingonberries and bilberries were excluded, as were also in vitro-studies, animal studies and epidemiological studies, as well as studies focusing on therapeutic effects, i.e. treatment of disease.

In total, five qualified bilberry studies were identified, which taken toghether suggest positive effects of blueberries on inflammation and risk of cardiovascular disease and type 2-diabetes (Habanova et al 2016, Karlsen et al 2010, Kolehmainen et al 2012, Lehtonen et al, 2011), while one study showed some increase in exercise-induced muscle weakness after blueberry intake (Lynn et al 2018). For lingonberries, only one qualified study was identified, which showed that rinsing the mouth with lingonberry juice reduced the inflammatory load in the oral cavity (Pärnänen et al 2019). The literature screening may have missed some studies, as it was not conducted systematically. However, it can be noted that there are very few studies that have looked at the health effects of bilberries and lingonberries in healthy people. In other words, there is an important knowledge gap to fill.

Swedish studies underway

There is relatively little research on berries and health in Sweden, but a couple of exciting studies are underway. One of them is led by Lovisa Heyman-Lindén, CEO of the research-based company Berry Lab, part of the Aventure group.

- With the current study, we wanted to investigate the effect of a product consisting mainly of Swedish bilberries and lingonberries on cognitive ability, cardiovascular disease risk markers and intestinal flora composition in healthy individuals. The study includes about 60 people who have been eating either the berry product in question or a reference product without berries for 12 weeks. Together with a study that we recently completed in collaboration with Ängelholm Hospital, we hope to contribute to a major step forward in knowledge about how we are affected by eating berries from the Swedish forests," says Lovisa Heyman-Lindén.

Another interesting study is the so-called BioAMI study, led by Ole Fröbert and Cecilia Berg at Örebro University, in collaboration with Lund University, Chalmers, Umeå University, Karlstad Hospital, Region Västmanland, Sahlgrenska University Hospital and Glukanova. In the BioAMI study, the researchers want to study whether bilberries and oats, together or separately, are useful in the secondary prevention of heart disease. The study is being conducted on patients who have either had a heart attack or have type 2-diabetes. The aim is for the study to last until it includes 900 patients. One of the researchers involved in the study is Rikard Landberg,  professor at Chalmers University of Technology.

- The BioAMI study is conducted in patients, but can contribute to a better understanding of mechanisms that may also be relevant for understanding how bilberries can help prevent heart disease in healthy people. There are already some theories about such mechanisms from previous studies on patients, which in turn led to the implementation of the BioAMI study," says Rikard Landberg.

- In connection with the BioAMI study, stability studies are also conducted to ensure that the molecules that the researchers believe have a health effect remain after processing and storage, which is important knowledge to have when developing innovative foods, says Rikard Landberg.

No authorised health claims 

For food companies, the ability to label and market foods with health claims is governed by EU Regulation 1924/2006 on nutrition and health claims. The basic principle is that only claims approved under the rules of this Regulation can be used in commercial communications to consumers. To be authorized, claims need to be substantiated by well-designed controlled studies, which support effects in healthy individuals. Given that the FINEST literature screening identified so few studies, it is hardly surprising that there are no authorized health claims for bilberries and lingonberries so far. In fact, there are currently no approved health claims for any specific berries, or for berries as a product group. However, for several years there has been a "waiting list" of proposed health claims for plant-based foods (so-called "botanicals") that have not yet been assessed. The waiting list includes some proposed claims for bilberries (but not for lingonberries). There is no timetable yet for decisions on claims on the waiting list. Until a decision is taken, there are some possibilities for companies to use health claims on the waiting list under their own responsibility.

There are also no authorized health claims for polyphenols. However, there are a large number of approved health claims for most vitamins and minerals, some of which could be relevant and allowed to be communicated for berry products. A basic condition of use is that the final product has a sufficiently high content of the nutrient in question. For berries, for example, this could be claims linked to the content of vitamin C and folate. However, products based on only bilberries and/or lingonberries may not reach the required levels for health claims on any vitamin.

Eat more berries!

In summary, we can conclude that bilberries and lingonberries have a natural place in a healthy diet, along with other berries, fruits and vegetables. Since many of us eat too little fruits, berries and vegetables, there are good reasons to eat more berries - and preferably bilberries and lingonberries, which are a hitherto underutilized resource in our Swedish forests (read more about this in the "Bärometern"). However, more well-designed studies are needed to better understand if and how bilberries and lingonberries contribute to specific health effects and, if so, for food companies to be able to communicate about these effects.