Throughout my life, I’ve been without lots of things: sleep, money, the right dress, electricity, the perfect pair of shoes, an inspired idea. You get the picture.

But there’s one thing that’s been a consistent comfort; one thing I’ve never been without. And I am always so very grateful for that one thing.

That one thing? FRIENDS.

Friends are essential for a happy life. For me, they keep me afloat when I feel myself going under; they’re my first line of defense when I’m down or troubled. There is something about the solidity of friendship that feels thrilling and comforting all at once. Some people might ask if you have a husband, a boyfriend, a partner that you enjoy a good relationship with, why do you still need friends?

To that, I say: it’s different. Friendships, at their best, are uncomplicated and sustaining; reasonable and free of emotional hurdles. They’re an invisible force that holds your hand securely and keeps you in a safe place.

The importance of friends and social networks is finally being acknowledged. Indeed, friendship has a profound effect on your physical and psychological health. Friends can be a powerful weapon in keeping your immune system functioning at its peak; study after study bears this out.

Need proof you need friends?

• Strong social networks go a long way: During a 10-year study period, older people with a large network of friends were 22 percent less likely to die than those with fewer friends.
• Friends are important for your head: Harvard researchers found that having strong friendships is a champion of brain health as we age.
• Close friends and cancer: A 2006 study of 3,000 nurses with breast cancer found that women without close friends were four times more likely to die of the disease than women with 10 or more friends.

Low social interaction was compared with other well-known health risk factors by scientists at Brigham Young University. They found that low social interaction is:

• Equivalent to smoking 15 cigarettes a day
• Equivalent to being an alcoholic
• More harmful than not exercising
• Twice as harmful as obesity

Losing a friend can have a powerful impact on health, too. Whether it is through death or disagreement, the pain and mourning packs a punch on immunity. Stress, sadness, loneliness, grief – they all follow loss. And what follows such intense emotions is a downward dive in your overall health. Stress hormones are released, causing a spike in blood pressure, heart rate, and blood sugar levels. And if stress hangs on for the long-term, other health problems crop up: depression, anxiety, obesity, and more.

Over the years, I’ve lost friends. I’m sure you have, too. It’s inevitable they will come and go. Lucky is the woman who is able to keep their childhood friends well into adulthood.

My two best friends both died within a year of one another; both of breast cancer. With each loss, a piece of myself was torn from me. With each loss, sadness and a huge empty space followed me wherever I went. I felt exposed and raw, yet strangely alone in my grief.

As with everything else, resiliency eventually surfaces and I moved on. I nurtured my other friendships, cherishing them even more than before. But I can’t help but wonder what life would be like if those two friends were still here.

Keep your friends close. Take pleasure in the benefits you gain from one another. Your health depends on it.

Sheryl Kraft is Health & Wellness Editor at EndlessBeauty.com